Currently, the REST API has become the standard for web application development, allowing you to break the development into independent parts. For the UI, various popular frameworks such as Angular, React, Vue and others are currently used. Backend developers can choose from a wide variety of languages and frameworks. Today I would like to talk about such a framework as NestJS. We are in TestMace We actively use it for internal projects. Using nest and package @nestjsx/crud, we will create a simple CRUD application.

Why NestJS

Recently, quite a lot of backend frameworks have appeared in the JavaScript community. And if in terms of functionality they provide opportunities similar to Nest, then it definitely wins in one thing - this is architecture. The following NestJS features allow you to create industrial applications and scale development to large teams:

using TypeScript as the main development language. Although NestJS supports JavaScript, some of the functionality may not work, especially when it comes to third-party packages;
the presence of a DI container, which allows you to create loosely coupled components;
the functionality of the framework itself is divided into independent interchangeable components. For example, under the hood as a framework can be used as ExpressAnd fastify, to work with the nest database out of the box provides bindings to typeform, mongoose, sequelize;
NestJS is platform independent and supports REST, GraphQL, Websockets, gRPC, etc.

The framework itself is inspired by the Angular frontend framework and conceptually has a lot in common with it.

Installing NestJS and Deploying a Project

Nest contains a package nest/cli, which allows you to quickly deploy a basic application framework. Install this package globally:

npm install --global @nest/cli

After installation, we will generate the basic framework of our application with the name nest-rest. This is done using the command nest new nest-rest.

nest new nest-rest

dmitrii@dmitrii-HP-ZBook-17-G3:~/projects $ nest new nest-rest
  We will scaffold your app in a few seconds..

CREATE /nest-rest/.prettierrc (51 bytes)
CREATE /nest-rest/README.md (3370 bytes)
CREATE /nest-rest/nest-cli.json (84 bytes)
CREATE /nest-rest/nodemon-debug.json (163 bytes)
CREATE /nest-rest/nodemon.json (67 bytes)
CREATE /nest-rest/package.json (1805 bytes)
CREATE /nest-rest/tsconfig.build.json (97 bytes)
CREATE /nest-rest/tsconfig.json (325 bytes)
CREATE /nest-rest/tslint.json (426 bytes)
CREATE /nest-rest/src/app.controller.spec.ts (617 bytes)
CREATE /nest-rest/src/app.controller.ts (274 bytes)
CREATE /nest-rest/src/app.module.ts (249 bytes)
CREATE /nest-rest/src/app.service.ts (142 bytes)
CREATE /nest-rest/src/main.ts (208 bytes)
CREATE /nest-rest/test/app.e2e-spec.ts (561 bytes)
CREATE /nest-rest/test/jest-e2e.json (183 bytes)

? Which package manager would you ️ to use? yarn
 Installation in progress... 

  Successfully created project nest-rest
  Get started with the following commands:

$ cd nest-rest
$ yarn run start

                          Thanks for installing Nest 
                 Please consider donating to our open collective
                        to help us maintain this package.

                 Donate: https://opencollective.com/nest

We will choose yarn as our package manager.
For now, you can start the server with the command npm start and going to the address http://localhost:3000 you can see the main page. However, this is not what we are here for and we are moving on.

Setting up work with the database

I chose PostrgreSQL as the DBMS for this article. There is no dispute about tastes, in my opinion, this is the most mature DBMS that has all the necessary features. As already mentioned, Nest provides integration with various packages for working with databases. Because Since my choice fell on PostgreSQL, it would be logical to choose TypeORM as the ORM. Install the necessary packages for integration with the database:

yarn add typeorm @nestjs/typeorm pg

In order, what each package is for:

typeorm - a package directly from the ORM itself;
@nestjs/typeorm - TypeORM package for NestJS. Adds modules for import into project modules, as well as a set of helper decorators;
pg is a driver for working with PostgreSQL.

Okay, the packages are installed, now you need to start the database itself. To deploy the base, I will use docker-compose.yml with the following content:

docker-compose.yml

version: '3.1'

services:
  db:
    image: postgres:11.2
    restart: always
    environment:
      POSTGRES_PASSWORD: example
    volumes:
      - ../db:/var/lib/postgresql/data
      - ./postgresql.conf:/etc/postgresql/postgresql.conf
    ports:
      - 5432:5432
  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080

As you can see, this file configures the launch of 2 containers:

db is a container directly with a database. In our case, postgresql version 11.2 is used;
adminer - database manager. Provides a web interface for viewing and managing the database.

To work with tcp connections, I added the following config.

postgresql.conf

# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
#   name = value
#
# (The "=" is optional.)  Whitespace may be used.  Comments are introduced with
# "#" anywhere on a line.  The complete list of parameter names and allowed
# values can be found in the PostgreSQL documentation.
#
# The commented-out settings shown in this file represent the default values.
# Re-commenting a setting is NOT sufficient to revert it to the default value;
# you need to reload the server.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal.  If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, run "pg_ctl reload", or execute
# "SELECT pg_reload_conf()".  Some parameters, which are marked below,
# require a server shutdown and restart to take effect.
#
# Any parameter can also be given as a command-line option to the server, e.g.,
# "postgres -c log_connections=on".  Some parameters can be changed at run time
# with the "SET" SQL command.
#
# Memory units:  kB = kilobytes        Time units:  ms  = milliseconds
#                MB = megabytes                     s   = seconds
#                GB = gigabytes                     min = minutes
#                TB = terabytes                     h   = hours
#                                                   d   = days
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.
#data_directory = 'ConfigDir'       # use data in another directory
# (change requires restart)
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
# (change requires restart)
#ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file
# (change requires restart)
# If external_pid_file is not explicitly set, no extra PID file is written.
#external_pid_file = ''         # write an extra PID file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
listen_addresses = '*'
#listen_addresses = 'localhost'     # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost'; use '*' for all
# (change requires restart)
#port = 5432                # (change requires restart)
#max_connections = 100          # (change requires restart)
#superuser_reserved_connections = 3 # (change requires restart)
#unix_socket_directories = '/tmp'   # comma-separated list of directories
# (change requires restart)
#unix_socket_group = ''         # (change requires restart)
#unix_socket_permissions = 0777     # begin with 0 to use octal notation
# (change requires restart)
#bonjour = off              # advertise server via Bonjour
# (change requires restart)
#bonjour_name = ''          # defaults to the computer name
# (change requires restart)
# - TCP Keepalives -
# see "man 7 tcp" for details
#tcp_keepalives_idle = 0        # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0        # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0       # TCP_KEEPCNT;
# 0 selects the system default
# - Authentication -
#authentication_timeout = 1min      # 1s-600s
#password_encryption = md5      # md5 or scram-sha-256
#db_user_namespace = off
# GSSAPI using Kerberos
#krb_server_keyfile = ''
#krb_caseins_users = off
# - SSL -
#ssl = off
#ssl_ca_file = ''
#ssl_cert_file = 'server.crt'
#ssl_crl_file = ''
#ssl_key_file = 'server.key'
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_min_protocol_version = 'TLSv1'
#ssl_max_protocol_version = ''
#ssl_dh_params_file = ''
#ssl_passphrase_command = ''
#ssl_passphrase_command_supports_reload = off
#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------
# - Memory -
#shared_buffers = 32MB          # min 128kB
# (change requires restart)
#huge_pages = try           # on, off, or try
# (change requires restart)
#temp_buffers = 8MB         # min 800kB
#max_prepared_transactions = 0      # zero disables the feature
# (change requires restart)
# Caution: it is not advisable to set max_prepared_transactions nonzero unless
# you actively intend to use prepared transactions.
#work_mem = 4MB             # min 64kB
#maintenance_work_mem = 64MB        # min 1MB
#autovacuum_work_mem = -1       # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB          # min 100kB
#shared_memory_type = mmap      # the default is the first option
# supported by the operating system:
#   mmap
#   sysv
#   windows
# (change requires restart)
#dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
#   posix
#   sysv
#   windows
#   mmap
# (change requires restart)
# - Disk -
#temp_file_limit = -1           # limits per-process temp file space
# in kB, or -1 for no limit
# - Kernel Resources -
#max_files_per_process = 1000       # min 25
# (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0          # 0-100 milliseconds (0 disables)
#vacuum_cost_page_hit = 1       # 0-10000 credits
#vacuum_cost_page_miss = 10     # 0-10000 credits
#vacuum_cost_page_dirty = 20        # 0-10000 credits
#vacuum_cost_limit = 200        # 1-10000 credits
# - Background Writer -
#bgwriter_delay = 200ms         # 10-10000ms between rounds
#bgwriter_lru_maxpages = 100        # max buffers written/round, 0 disables
#bgwriter_lru_multiplier = 2.0      # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 0       # measured in pages, 0 disables
# - Asynchronous Behavior -
#effective_io_concurrency = 1       # 1-1000; 0 disables prefetching
#max_worker_processes = 8       # (change requires restart)
#max_parallel_maintenance_workers = 2   # taken from max_parallel_workers
#max_parallel_workers_per_gather = 2    # taken from max_parallel_workers
#parallel_leader_participation = on
#max_parallel_workers = 8       # maximum number of max_worker_processes that
# can be used in parallel operations
#old_snapshot_threshold = -1        # 1min-60d; -1 disables; 0 is immediate
# (change requires restart)
#backend_flush_after = 0        # measured in pages, 0 disables
#------------------------------------------------------------------------------
# WRITE-AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
#wal_level = replica            # minimal, replica, or logical
# (change requires restart)
#fsync = on             # flush data to disk for crash safety
# (turning this off can cause
# unrecoverable data corruption)
#synchronous_commit = on        # synchronization level;
# off, local, remote_write, remote_apply, or on
#wal_sync_method = fsync        # the default is the first option
# supported by the operating system:
#   open_datasync
#   fdatasync (default on Linux)
#   fsync
#   fsync_writethrough
#   open_sync
#full_page_writes = on          # recover from partial page writes
#wal_compression = off          # enable compression of full-page writes
#wal_log_hints = off            # also do full page writes of non-critical updates
# (change requires restart)
#wal_buffers = -1           # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms       # 1-10000 milliseconds
#wal_writer_flush_after = 1MB       # measured in pages, 0 disables
#commit_delay = 0           # range 0-100000, in microseconds
#commit_siblings = 5            # range 1-1000
# - Checkpoints -
#checkpoint_timeout = 5min      # range 30s-1d
#max_wal_size = 1GB
#min_wal_size = 80MB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 0     # measured in pages, 0 disables
#checkpoint_warning = 30s       # 0 disables
# - Archiving -
#archive_mode = off     # enables archiving; off, on, or always
# (change requires restart)
#archive_command = ''       # command to use to archive a logfile segment
# placeholders: %p = path of file to archive
#               %f = file name only
# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0        # force a logfile segment switch after this
# number of seconds; 0 disables
# - Archive Recovery -
# These are only used in recovery mode.
#restore_command = ''       # command to use to restore an archived logfile segment
# placeholders: %p = path of file to restore
#               %f = file name only
# e.g. 'cp /mnt/server/archivedir/%f %p'
# (change requires restart)
#archive_cleanup_command = ''   # command to execute at every restartpoint
#recovery_end_command = ''  # command to execute at completion of recovery
# - Recovery Target -
# Set these only when performing a targeted recovery.
#recovery_target = ''       # 'immediate' to end recovery as soon as a
# consistent state is reached
# (change requires restart)
#recovery_target_name = ''  # the named restore point to which recovery will proceed
# (change requires restart)
#recovery_target_time = ''  # the time stamp up to which recovery will proceed
# (change requires restart)
#recovery_target_xid = ''   # the transaction ID up to which recovery will proceed
# (change requires restart)
#recovery_target_lsn = ''   # the WAL LSN up to which recovery will proceed
# (change requires restart)
#recovery_target_inclusive = on # Specifies whether to stop:
# just after the specified recovery target (on)
# just before the recovery target (off)
# (change requires restart)
#recovery_target_timeline = 'latest'    # 'current', 'latest', or timeline ID
# (change requires restart)
#recovery_target_action = 'pause'   # 'pause', 'promote', 'shutdown'
# (change requires restart)
#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------
# - Sending Servers -
# Set these on the master and on any standby that will send replication data.
#max_wal_senders = 10       # max number of walsender processes
# (change requires restart)
#wal_keep_segments = 0      # in logfile segments; 0 disables
#wal_sender_timeout = 60s   # in milliseconds; 0 disables
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
#track_commit_timestamp = off   # collect timestamp of transaction commit
# (change requires restart)
# - Master Server -
# These settings are ignored on a standby server.
#synchronous_standby_names = '' # standby servers that provide sync rep
# method to choose sync standbys, number of sync standbys,
# and comma-separated list of application_name
# from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0   # number of xacts by which cleanup is delayed
# - Standby Servers -
# These settings are ignored on a master server.
#primary_conninfo = ''          # connection string to sending server
# (change requires restart)
#primary_slot_name = ''         # replication slot on sending server
# (change requires restart)
#promote_trigger_file = ''      # file name whose presence ends recovery
#hot_standby = on           # "off" disallows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s    # max delay before canceling queries
# when reading WAL from archive;
# -1 allows indefinite delay
#max_standby_streaming_delay = 30s  # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off     # send info from standby to prevent
# query conflicts
#wal_receiver_timeout = 60s     # time that receiver waits for
# communication from master
# in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s   # time to wait before retrying to
# retrieve WAL after a failed attempt
#recovery_min_apply_delay = 0       # minimum delay for applying changes during recovery
# - Subscribers -
# These settings are ignored on a publisher.
#max_logical_replication_workers = 4    # taken from max_worker_processes
# (change requires restart)
#max_sync_workers_per_subscription = 2  # taken from max_logical_replication_workers
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_parallel_append = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on
#enable_partitionwise_join = off
#enable_partitionwise_aggregate = off
#enable_parallel_hash = on
#enable_partition_pruning = on
# - Planner Cost Constants -
#seq_page_cost = 1.0            # measured on an arbitrary scale
#random_page_cost = 4.0         # same scale as above
#cpu_tuple_cost = 0.01          # same scale as above
#cpu_index_tuple_cost = 0.005       # same scale as above
#cpu_operator_cost = 0.0025     # same scale as above
#parallel_tuple_cost = 0.1      # same scale as above
#parallel_setup_cost = 1000.0   # same scale as above
#jit_above_cost = 100000        # perform JIT compilation if available
# and query more expensive than this;
# -1 disables
#jit_inline_above_cost = 500000     # inline small functions if query is
# more expensive than this; -1 disables
#jit_optimize_above_cost = 500000   # use expensive JIT optimizations if
# query is more expensive than this;
# -1 disables
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB
# - Genetic Query Optimizer -
#geqo = on
#geqo_threshold = 12
#geqo_effort = 5            # range 1-10
#geqo_pool_size = 0         # selects default based on effort
#geqo_generations = 0           # selects default based on effort
#geqo_selection_bias = 2.0      # range 1.5-2.0
#geqo_seed = 0.0            # range 0.0-1.0
# - Other Planner Options -
#default_statistics_target = 100    # range 1-10000
#constraint_exclusion = partition   # on, off, or partition
#cursor_tuple_fraction = 0.1        # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8        # 1 disables collapsing of explicit
# JOIN clauses
#force_parallel_mode = off
#jit = on               # allow JIT compilation
#plan_cache_mode = auto         # auto, force_generic_plan or
# force_custom_plan
#------------------------------------------------------------------------------
# REPORTING AND LOGGING
#------------------------------------------------------------------------------
# - Where to Log -
#log_destination = 'stderr'     # Valid values are combinations of
# stderr, csvlog, syslog, and eventlog,
# depending on platform.  csvlog
# requires logging_collector to be on.
# This is used when logging to stderr:
#logging_collector = off        # Enable capturing of stderr and csvlog
# into log files. Required to be on for
# csvlogs.
# (change requires restart)
# These are only used if logging_collector is on:
#log_directory = 'log'          # directory where log files are written,
# can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'    # log file name pattern,
# can include strftime() escapes
#log_file_mode = 0600           # creation mode for log files,
# begin with 0 to use octal notation
#log_truncate_on_rotation = off     # If on, an existing log file with the
# same name as the new log file will be
# truncated rather than appended to.
# But such truncation only occurs on
# time-driven rotation, not on restarts
# or size-driven rotation.  Default is
# off, meaning append to existing files
# in all cases.
#log_rotation_age = 1d          # Automatic rotation of logfiles will
# happen after that time.  0 disables.
#log_rotation_size = 10MB       # Automatic rotation of logfiles will
# happen after that much log output.
# 0 disables.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
#syslog_sequence_numbers = on
#syslog_split_messages = on
# This is only relevant when logging to eventlog (win32):
# (change requires restart)
#event_source = 'PostgreSQL'
# - When to Log -
#log_min_messages = warning     # values in order of decreasing detail:
#   debug5
#   debug4
#   debug3
#   debug2
#   debug1
#   info
#   notice
#   warning
#   error
#   log
#   fatal
#   panic
#log_min_error_statement = error    # values in order of decreasing detail:
#   debug5
#   debug4
#   debug3
#   debug2
#   debug1
#   info
#   notice
#   warning
#   error
#   log
#   fatal
#   panic (effectively off)
#log_min_duration_statement = -1    # logs statements and their durations
# according to log_statement_sample_rate. -1 is disabled,
# 0 logs all statement, > 0 logs only statements running at
# least this number of milliseconds.
#log_statement_sample_rate = 1  # Fraction of logged statements over
# log_min_duration_statement. 1.0 logs all statements,
# 0 never logs.
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default      # terse, default, or verbose messages
#log_hostname = off
#log_line_prefix = '%m [%p] '       # special values:
#   %a = application name
#   %u = user name
#   %d = database name
#   %r = remote host and port
#   %h = remote host
#   %p = process ID
#   %t = timestamp without milliseconds
#   %m = timestamp with milliseconds
#   %n = timestamp with milliseconds (as a Unix epoch)
#   %i = command tag
#   %e = SQL state
#   %c = session ID
#   %l = session line number
#   %s = session start timestamp
#   %v = virtual transaction ID
#   %x = transaction ID (0 if none)
#   %q = stop here in non-session
#        processes
#   %% = '%'
# e.g. '<%u%%%d> '
#log_lock_waits = off           # log lock waits >= deadlock_timeout
#log_statement = 'none'         # none, ddl, mod, all
#log_replication_commands = off
#log_temp_files = -1            # log temporary files equal or larger
# than the specified size in kilobytes;
# -1 disables, 0 logs all temp files
#log_timezone = 'GMT'
#------------------------------------------------------------------------------
# PROCESS TITLE
#------------------------------------------------------------------------------
#cluster_name = ''          # added to process titles if nonempty
# (change requires restart)
#update_process_title = on
#------------------------------------------------------------------------------
# STATISTICS
#------------------------------------------------------------------------------
# - Query and Index Statistics Collector -
#track_activities = on
#track_counts = on
#track_io_timing = off
#track_functions = none         # none, pl, all
#track_activity_query_size = 1024   # (change requires restart)
#stats_temp_directory = 'pg_stat_tmp'
# - Monitoring -
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off
#------------------------------------------------------------------------------
# AUTOVACUUM
#------------------------------------------------------------------------------
#autovacuum = on            # Enable autovacuum subprocess?  'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1   # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
#autovacuum_max_workers = 3     # max number of autovacuum subprocesses
# (change requires restart)
#autovacuum_naptime = 1min      # time between autovacuum runs
#autovacuum_vacuum_threshold = 50   # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50  # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2   # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1  # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000  # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000    # maximum multixact age
# before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 2ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1  # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------
# - Statement Behavior -
#client_min_messages = notice       # values in order of decreasing detail:
#   debug5
#   debug4
#   debug3
#   debug2
#   debug1
#   log
#   notice
#   warning
#   error
#search_path = '"$user", public'    # schema names
#row_security = on
#default_tablespace = ''        # a tablespace name, '' uses the default
#temp_tablespaces = ''          # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0          # in milliseconds, 0 is disabled
#lock_timeout = 0           # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0    # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_freeze_table_age = 150000000
#vacuum_cleanup_index_scale_factor = 0.1    # fraction of total number of tuples
# before index cleanup, 0 always performs
# index cleanup
#bytea_output = 'hex'           # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_fuzzy_search_limit = 0
#gin_pending_list_limit = 4MB
# - Locale and Formatting -
#datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
#timezone = 'GMT'
#timezone_abbreviations = 'Default'     # Select the set of available time zone
# abbreviations.  Currently, there are
#   Default
#   Australia (historical usage)
#   India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 1         # min -15, max 3; any value >0 actually
# selects precise output mode
#client_encoding = sql_ascii        # actually, defaults to database
# encoding
# These settings are initialized by initdb, but they can be changed.
#lc_messages = 'C'          # locale for system error message
# strings
#lc_monetary = 'C'          # locale for monetary formatting
#lc_numeric = 'C'           # locale for number formatting
#lc_time = 'C'              # locale for time formatting
# default configuration for text search
#default_text_search_config = 'pg_catalog.simple'
# - Shared Library Preloading -
#shared_preload_libraries = ''  # (change requires restart)
#local_preload_libraries = ''
#session_preload_libraries = ''
#jit_provider = 'llvmjit'       # JIT library to use
# - Other Defaults -
#dynamic_library_path = '$libdir'
#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
#max_locks_per_transaction = 64     # min 10
# (change requires restart)
#max_pred_locks_per_transaction = 64    # min 10
# (change requires restart)
#max_pred_locks_per_relation = -2   # negative values mean
# (max_pred_locks_per_transaction
#  / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2            # min 0
#------------------------------------------------------------------------------
# VERSION AND PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
#array_nulls = on
#backslash_quote = safe_encoding    # on, off, or safe_encoding
#escape_string_warning = on
#lo_compat_privileges = off
#operator_precedence_warning = off
#quote_all_identifiers = off
#standard_conforming_strings = on
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------
#exit_on_error = off            # terminate session on any error?
#restart_after_crash = on       # reinitialize after backend crash?
#data_sync_retry = off          # retry or panic on failure to fsync
# data?
# (change requires restart)
#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------
# These options allow settings to be loaded from files other than the
# default postgresql.conf.
#include_dir = 'conf.d'         # include files ending in '.conf' from
# directory 'conf.d'
#include_if_exists = 'exists.conf'  # include file only if it exists
#include = 'special.conf'       # include file
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------
# Add settings for extensions here

That's all, you can run the containers with the command docker-compose up -d. Or in a separate console with the command docker-compose up.

So, the packages were installed, the base was launched, it remains to make them friends with each other. To do this, add the ormconfig.js file to the root of the project with the following content:

ormconfig.js

const process = require('process');
const username = process.env.POSTGRES_USER || "postgres";
const password = process.env.POSTGRES_PASSWORD || "example";
module.exports = {
"type": "postgres",
"host": "localhost",
"port": 5432,
username,
password,
"database": "postgres",
"synchronize": true,
"dropSchema": false,
"logging": true,
"entities": [__dirname + "/src/**/*.entity.ts", __dirname + "/dist/**/*.entity.js"],
"migrations": ["migrations/**/*.ts"],
"subscribers": ["subscriber/**/*.ts", "dist/subscriber/**/.js"],
"cli": {
"entitiesDir": "src",
"migrationsDir": "migrations",
"subscribersDir": "subscriber"
}
}

This configuration will be used for cli typeorm.

Let's take a closer look at this configuration. In lines 3 and 4 we get the username and password from the environment variables. This is handy when you have multiple environments (dev, stage, prod, etc). The default username is postgres, the password is example. Otherwise, the config is trivial, so we will focus only on the most interesting parameters:

synchronize Specifies whether the database schema should be automatically created when the application starts. Be careful with this option and do not use it in production, otherwise you will lose data. This option is useful when developing and debugging an application. As an alternative to this option, you can use the command schema:sync from CLI TypeORM.
dropSchema - Drop the schema each time a connection is established. Also, like the previous one, this option should be used only during the development and debugging of the application.
entities - which paths to look for the description of models. Please note that mask search is supported.
cli.entitiesDir is the directory where models created from CLI TypeORM should be added by default.

In order for us to use all the features of TypeORM in our Nest application, we need to import the module TypeOrmModule в AppModule. Those. your AppModule will look like this:

app.module.ts

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { TypeOrmModule } from '@nestjs/typeorm';
import * as process from "process";
const username = process.env.POSTGRES_USER || 'postgres';
const password = process.env.POSTGRES_PASSWORD || 'example';
@Module({
imports: [
TypeOrmModule.forRoot({
type: 'postgres',
host: 'localhost',
port: 5432,
username,
password,
database: 'postgres',
entities: [__dirname + '/**/*.entity{.ts,.js}'],
synchronize: true,
}),
],
controllers: [AppController],
providers: [AppService],
})
export class AppModule {}

As you have noticed, in the method forRoot the same configuration for working with the database is passed as in the ormconfig.ts file

The final touch remains - to add a few tasks for working with TypeORM in package.json. The fact is that the CLI is written in javascript and runs in the nodejs environment. However, all of our models and migrations will be written in typescript. Therefore, it is necessary to transpile our migrations and models before using the CLI. To do this, we need the ts-node package:

yarn add -D ts-node

After that, add the necessary commands to package.json:

"typeorm": "ts-node -r tsconfig-paths/register ./node_modules/typeorm/cli.js",
"migration:generate": "yarn run typeorm migration:generate -n",
"migration:create": "yarn run typeorm migration:create -n",
"migration:run": "yarn run typeorm migration:run"

The first command, typeorm, adds a ts-node wrapper to launch the TypeORM cli. The rest of the commands are handy shortcuts that you, as a developer, will use almost every day:
migration:generate - create migrations based on changes in your models.
migration:create - creating an empty migration.
migration:run - start migrations.
Well, now that’s all for sure, we have added the necessary packages, configured the application to work with the database both from the cli and from the application itself, and also launched the DBMS. It's time to add logic to our application.

Installing packages for creating CRUD

Using only Nest, you can create an API that allows you to create, read, update, and delete an entity. Such a solution will be as flexible as possible, but in some cases it will be redundant. For example, if you need to quickly create a prototype, then you can often sacrifice flexibility for the sake of development speed. Many frameworks provide the functionality of generating CRUD by describing the data model of a particular entity. And Nest is no exception! This functionality is provided by the package @nestjsx/crud. Its possibilities are very interesting:

easy installation and configuration;
independence from the DBMS;
powerful query language with the ability to filter, paginate, sort, load relationships and nested entities, caching, etc.;
a package for generating requests for the front-end;
easy redefinition of controller methods;
small config;
swagger documentation support.

The functionality is divided into several packages:

@nestjsx/crud - the base package provided by the decorator raw() for route generation, configuration and validation;
@nestjsx/crud-request - a package that provides a query builder / parser for use on the frontend side;
@nestjsx/crud-typeform - a package for integration with TypeORM, which provides a basic TypeOrmCrudService service with CRUD methods for working with entities in the database.

For this guide, we will need packages nestjsx/crud and nestjsx/crud-typeform. First, let's put them

yarn add @nestjsx/crud class-transformer class-validator

Plans for class-transformer и class-validator in this application are required for the declarative description of the rules for transforming model instances and validating incoming requests, respectively. These packages are from the same author, so the interfaces are similar.

Direct implementation of CRUD

As an example of a model, we will take a list of users. Users will have the following fields: id, username, displayName, email. id - auto-increment field, email и username - unique fields. Everything is simple! It remains to realize our idea in the form of a Nest application.
First you need to create a module userswho will be responsible for working with users. Let's use the cli from NestJS, and in the root directory of our project we will execute the command nest g module users.

nest g module users

dmitrii@dmitrii-HP-ZBook-17-G3:~/projects/nest-rest git:(master*)$ nest g module users
CREATE /src/users/users.module.ts (82 bytes)
UPDATE /src/app.module.ts (312 bytes)

In this module, we will add the entities folder, where we will have the models of this module. In particular, let's add the user.entity.ts file here with a description of the user model:

user.entity.ts

import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
@Entity()
export class User {
@PrimaryGeneratedColumn()
id: string;
@Column({unique: true})
email: string;
@Column({unique: true})
username: string;
@Column({nullable: true})
displayName: string;
}

In order for this model to be "seen" by our application, it is necessary in the module UsersModule import TypeOrmModule the following content:

users.module.ts

import { Module } from '@nestjs/common';
import { UsersController } from './controllers/users/users.controller';
import { UsersService } from './services/users/users.service';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from './entities/user.entity';
@Module({
controllers: [UsersController],
providers: [UsersService],
imports: [
TypeOrmModule.forFeature([User])
]
})
export class UsersModule {}

So here we are importing TypeOrmModule, where as a method parameter forFeature specify the list of models related to this module.

It remains to create the corresponding entity in the database. For these purposes, the mechanism of migrations is used. To create a migration based on model changes, run the command npm run migration:generate -- CreateUserTable:

Spoiler header

$ npm run migration:generate -- CreateUserTable
Migration /home/dmitrii/projects/nest-rest/migrations/1563346135367-CreateUserTable.ts has been generated successfully.
Done in 1.96s.

We didn't have to write the migration by hand, everything magically happened. Isn't that a miracle! However, this is not all. Let's take a look at the generated migration file:

1563346135367-CreateUserTable.ts

import {MigrationInterface, QueryRunner} from "typeorm";
export class CreateUserTable1563346816726 implements MigrationInterface {
public async up(queryRunner: QueryRunner): Promise<any> {
await queryRunner.query(`CREATE TABLE "user" ("id" SERIAL NOT NULL, "email" character varying NOT NULL, "username" character varying NOT NULL, "displayName" character varying, CONSTRAINT "UQ_e12875dfb3b1d92d7d7c5377e22" UNIQUE ("email"), CONSTRAINT "UQ_78a916df40e02a9deb1c4b75edb" UNIQUE ("username"), CONSTRAINT "PK_cace4a159ff9f2512dd42373760" PRIMARY KEY ("id"))`);
}
public async down(queryRunner: QueryRunner): Promise<any> {
await queryRunner.query(`DROP TABLE "user"`);
}
}

As you can see, not only the method for starting the migration was automatically generated, but also the method for rolling it back. Fantastic!
It remains only to roll this migration. This is done by the following command:

npm run migration:run.

That's it, now the schema changes have migrated to the database.
Next, we will create a service that will be responsible for working with users and inherit it from TypeOrmCrudService. It is necessary to pass the repository of the entity of interest to the parameter of the parent constructor, in our case User repository.

users.service.ts

import { Injectable } from '@nestjs/common';
import { TypeOrmCrudService } from '@nestjsx/crud-typeorm';
import { User } from '../../entities/user.entity';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
@Injectable()
export class UsersService extends TypeOrmCrudService<User>{
constructor(@InjectRepository(User) usersRepository: Repository<User>){
super(usersRepository);
}
}

We need this service in the controller users. To create a controller, type in the console nest g controller users/controllers/users

nest g controller users/controllers/users

dmitrii@dmitrii-HP-ZBook-17-G3:~/projects/nest-rest git:(master*)$ nest g controller users/controllers/users
CREATE /src/users/controllers/users/users.controller.spec.ts (486 bytes)
CREATE /src/users/controllers/users/users.controller.ts (99 bytes)
UPDATE /src/users/users.module.ts (188 bytes)

Open this controller and edit to add some magic nestjsx/crud. per class UsersController Let's add a decorator like this:

@Crud({
model: {
type: User
}
})

raw is a decorator that adds the necessary methods to the controller to work with the model. The model type is indicated in the field model.type decorator configuration.
The second step is to implement the interface CrudController<User>. The “assembled” controller code looks like this:

import { Controller } from '@nestjs/common';
import { Crud, CrudController } from '@nestjsx/crud';
import { User } from '../../entities/user.entity';
import { UsersService } from '../../services/users/users.service';
@Crud({
model: {
type: User
}
})
@Controller('users')
export class UsersController implements CrudController<User>{
constructor(public service: UsersService){}
}

And it's all! Now the controller supports the entire set of operations with the model! Don't believe? Let's try our application in action!

Scripting Requests in TestMace

To test our service, we will use the IDE to work with the API TestMace. Why Test Mac? Compared with similar products, it has the following advantages:

powerful work with variables. At the moment, there are several types of variables, each of which performs a specific role: built-in variables, dynamic variables, environment variables. Each variable belongs to some node with support for the inheritance mechanism;
easy scripting without programming. This will be discussed below;
human-readable format that allows you to save the project in version control systems;
auto-completion, syntax highlighting, highlighting variable values;
API description support with the ability to import from Swagger.

Let's start our server with the command npm start and try to access the list of users. The list of users, judging by our controller configuration, can be obtained from the url localhost:3000/users. Let's make a request for this url.
After running TestMace, you can see this interface:

At the top left is the project tree with the root node Project. Let's try to create the first request to get a list of users. To do this, we will create RequestStep node. This is done in the context menu of the Project node. Add node -> RequestStep.

Paste localhost:3000/users into the URL field and run the request. We get 200 code with an empty array in the response body. It's understandable, we haven't added anyone yet.
Let's create a script that will include the following steps:

user creation;
query by id of the newly created user;
delete by user id created in step 1.

So let's go. For convenience, let's create a node like Folder. In fact, this is just a folder in which we will save the entire script. To create a Folder node, in the context menu of the Project node, select Add node -> Folder. Let's call the node check-create. Inside the node check-create Let's create our first request to create a user. Let's name the newly created node create-user. That is, at the moment the node hierarchy will look like this:

Let's go to the open tab create-user node. Let's enter the following parameters for the request:

Request type - POST
URL - localhost:3000/users
Body - JSON with value {"email": "[email protected]", "displayName": "New user", "username": "user"}

Let's execute this request. Our application says that the entry has been created.

Well, let's check this fact. In order to operate with the id of the created user in subsequent steps, this parameter must be saved. This mechanism is perfect for this. dynamic variables. Let's take a look at how we work with them using our example. In the parsed tab of the response, at the id node in the context menu, select the item Assign to variable. The following parameters must be specified in the dialog box:

Node - in which of the ancestors to create a dynamic variable. Let's choose check-create
variable name is the name of this variable. Let's call userId.

Here is how the process of creating a dynamic variable looks like:

Now, each time this query is executed, the value of the dynamic variable will be updated. And since dynamic variables support the mechanism of hierarchical inheritance, variable userId will be available in descendants check-create node of any nesting level.
In the next request, this variable will be useful to us. Namely, we will request a newly created user. As a child of a node check-create we will create a request check-if exists with parameter url equal localhost:3000/users/${$dynamicVar.userId}. View construction ${variable_name} is getting the value of a variable. Because we have a dynamic variable, then to get it you need to refer to the object $dynamicVar, i.e. completely accessing a dynamic variable userId will look like this ${$dynamicVar.userId}. Let's execute the request and make sure that the data is requested correctly.
The last touch remains - to make a request for deletion. We need it not only to check the operation of the removal, but also, so to speak, to clean up after ourselves in the database, because the email and username fields are unique. So, in the check-create node, we will create a delete-user request with the following parameters

Request Type - DELETE
URL - localhost:3000/users/${$dynamicVar.userId}

We launch. We wait. enjoy the result)

Well, now we can run this script completely at any time. To run the script, select from the context menu check-create knot point Run.

The nodes in the script will be executed one after the other
You can save this script to your project by running File -> Save project.

Conclusion

All the chips of the tools used simply could not fit into the format of this article. As for the main culprit - the package nestjsx/crud - the following topics remained uncovered:

custom validation and transformation of models;
powerful query language and its convenient use on the front;
redefining and adding new methods to crud controllers;
swagger support;
caching management.

However, even what is described in the article is enough to understand that even such an enterprise framework as NestJS has tools for rapid application prototyping. And such a cool IDE as TestMace allows you to maintain a set pace.

The source code for this article, along with the project TestMace, available in the repository https://github.com/TestMace/nest-rest. To open a project TestMace it is enough to execute in the application File -> Open project.

Source: habr.com

Fast CRUD creation with nest, @nestjsx/crud and TestMace