calustra. substantivo femenino:

Construción rural, de forma xeralmente rectangular, feita sobre columnas e con moitas aberturas nas paredes para facilitar a ventilación, que se utiliza fundamentalmente para gardar o millo e outros produtos agrícolas.

Gardan o millo na calustra.

Intro

calustra is a database connector.

Currently, supported databases are:

• PostgreSQL (through pg-promise).
• SQLite (through sqlite3).

We may add support for other databases (MySql, MsSql, ...) in the future... or may not.

Install

npm install calustra

Getting Started

calustra exposes just the method getConnection which returns a Connection object. With that connection, you may select(query), selectOne(query), execute(query) or executeAndCount(query) some SQL query.

You can also do .getModel(table_name), which returns a Model object.

You can also import some interesting SQL query tools from calustra/query.

import {getConnection} from 'calustra'

// Init connection
const config= {
  dialect:  'postgres',
  host:     'localhost',
  port:     5432,
  database: 'calustra',
  user:     'postgres',
  password: 'postgres'
}
const options= {
  log: 'debug',
  tables: ['screw_stock'],
  cache: {type: 'memory'},
  reset: true
}
const conn = await getConnection(config, options)

// create a table
const q_drop = `DROP TABLE IF EXISTS screw_stock`
await conn.execute(q_drop)

const q_create = `
  CREATE TABLE screw_stock (
    id           serial,
    screw_type   TEXT NOT NULL,
    stock        INT
  )`
await conn.execute(q_create)

// fill table
const data = [
  ['Wood Screws', 1034],
  ['Machine Screws', 3545],
  ['Thread Cutting Machine Screws', 466],
  ['Sheet Metal Screws', 6436],
  ['Self Drilling Screws', 265],
  ['Hex Bolts', 3653],
  ['Carriage Bolts', 63],
  ['Tag Bolts', 3573]
]

//
// Let's play using connection directly
//
const q_insert = 'INSERT INTO screw_stock (screw_type, stock) VALUES ($1, $2)
for (const d of data) {
  await conn.execute(q_insert, d)
}

// select many records
const q_select = 'SELECT * FROM screw_stock'
const screws = await conn.select(q_select)

// select one record
const q_select_one = 'SELECT * FROM screw_stock WHERE screw_type = $1'
const hex_bolts = await conn.selectOne(q_select_one, ['Hex Bolts'])

// clean some records
const q_del = 'DELETE FROM screw_stock WHERE stock >= $1'
const del_records = await conn.executeAndCount(q_del, [1000])

//
// Let's play using models
//

const ScrewStock = connection.getModel('screw_stock')

// fill table
for (const d of data) {
  await ScrewStock.insert({screw_type: d[0], stock: d[1]})
}

// select many records
const read_filter = {screw_type: ['Hex Bolts', 'Tag Bolts']}
const screws = await ScrewStock.read(read_filter)

// update one record
const upd_data = {stock: 1234}
const upd_filter = {screw_type: 'Tag Bolts'}
const upd_rows = await ScrewStock.update(upd_data, upd_filter)

// clean some records
const del_filter = {screw_type: 'Tag Bolts'}
const del_rows = await ScrewStock.delete(del_filter)

API

await getConnection(configOrSelector, options)

Initializes and returns a connection object.

Connections are cached. The first time you init the connection, you have to pass a config object. But for further usages of the connection, you can take the cached connection just by passing a selector.

config

Contains the connection parameters (which depend on the database).

For PostgreSQL:

  config= {
    dialect:  'postgres',
    host:     'localhost',
    port:     5432,
    database: 'calustra',
    user:     'postgres',
    password: 'postgres',
    // Maximum/Minimum number of connection in pool
    max: 5,
    min: 0,
    // The maximum time, in milliseconds, that a connection can be idle before being released. 
    // Use with combination of evict for proper working, for more details read 
    // https://github.com/coopernurse/node-pool/issues/178#issuecomment-327110870
    idleTimeoutMillis: 10000,
    allowExitOnIdle: true
  }

For SQLite:

  config={
    dialect:  'sqlite',
    filename: ':memory:',

    verbose:   true,
    
    // https://github.com/mapbox/node-sqlite3/wiki/Caching
    cached:    true,
    
    /*user:     'sqlite',
    password: 'sqlite'*/

    trace: undefined,
    profile: undefined,
    busyTimeout: undefined
  }

selector

It will be matched against the config object you had initialized the connection with.

Given this, the most easy thing to do is to just specify the database as the selector if using PostgreSQL, or the filename if using SQLite. But that's up to you!

options

log

It can be a string with the log level (silly, debug, info, warn, error) or a class exposing methods named as those log levels.

Some examples:

  options= {    
    log: 'debug'
  }

class CustomLogger {
  _log(l, s) {
    console.log(`[${l}] ${s}`)
  }
  
  silly(s) { this.log('silly', s) }
  debug(s) { this.log('debug', s) }
  info(s)  { this.log('info', s) }
  warn(s)  { this.log('warn', s) }
  error(s) { this.log('error', s) }
}

const options= {    
    log: CustomLogger
}

cache

Options to be passed to cacheiro. Default cache type is memory.

If false, connections are not cached.

reset

If true, cached connections will be ignored. Connection will be re-created. Default is false.

tables

List of tables in the database which will be accessible trough getModel(). Each item in the list may be an string (the table name) or an object like this:

{
  name: 'table_name',
  schema: 'public',
  useDateFields: {
    use: false,
    fieldNames: {
      created_at: 'created_at', 
      last_update_at: 'last_update_at'
    },
    now: () => intre_now()
  },
  
  checkBeforeDelete: [
    "another_table.field_id"
  ],
  
  triggers: {
    beforeRead   : <callback>,
    afterRead    : <callback>,
    beforeInsert : <callback>,
    afterInsert  : <callback>,
    beforeUpdate : <callback>,
    afterUpdate  : <callback>,
    beforeDelete : <callback>,
    afterDelete  : <callback>
  },
}

table.checkBeforeDelete

An array of db fields like ['table_one.field_two', 'table_three.field_one'].

It is used to prevent unwanted deletions which are not covered by a SQL relation.

It only affects to deletions which are filtered by id. For example:

const conn = await getConnection(config, {
  tables: [{
    name: 'screw_stock',
    checkBeforeDelete: ['screw_stats.screw_stock_id']
  }]
})

const ScrewStock = connection.getModel('screw_stock')

const del_filter = {id: 1}
const del_rows = await ScrewStock.delete(del_filter)

If some record exists in screw_stats table with screw_stock_id= 1, then the ScrewStock.delete will fail.

table.useDateFields

calustra knows that a very extended approach is to have fields like created_at or last_update_at in your tables. This option will help with that.

Here you can specify an object like this:

import {intre_now} from 'intre'

const conn = await getConnection(config, {
  tables: [{
    name: 'screw_stock',
    useDateFields: {
      use: true,
      fieldNames: {
        created_at: 'created_at', 
        last_update_at: 'last_update_at'
      },
      now: () => intre_now()
    }
  }]
})

You can also simply specify a boolean value. If true, above defaults will be used.

As you can imagine, calustra will automatically update this fields after every insert (created_at field) or update (last_update_at field).

table.triggers

Triggers are used to customize every query phase. A trigger is a function containing specific parameters and returning specific array of values. Available ones are:

• beforeInsert(conn params, options) returns [params, options, allow]
• afterInsert(conn id, params, options) return id
• beforeUpdate(conn params, filter, options) returns [params, filter, options, allow]
• afterUpdate(conn rows, params, filter, options) returns rows
• beforeDelete(conn filter, options) returns [filter, options, allow]
• afterDelete(conn rows, filter, options) returns rows

You can use them to abort queries (allow=false), to customize params on the fly before the query is executed, to customize the returning results, etc.

Connection object

async connection.select(query, values, options)

• query: string with SQL query. It may contain wildcards ($1, $2...) or (?, ?...).
• values: array of values if query contains wildcards
• options:
  • transaction
  • log: if false, logging is disabled for this particular call
  • silent_fail: can be true (will return undefined as query results) or false (default, exception will be propagated).

Returns an array of objects with the result of the query.

async connection.selectOne(query, values, options)

• query: string with SQL query. It may contain wildcards ($1, $2...) or (?, ?...).
• values: array of values if query contains wildcards
• options:
  • transaction
  • log: if false, logging is disabled for this particular call
  • omitWarning: by default, if query returns more than one record, a logging warning is shown. If omitWarning is true, this warning is ignored.
  • silent_fail: can be true (will return undefined as query results) or false (default, exception will be propagated).

Returns an object with the result of the query.

async connection.execute(query, values, options)

• query: string with SQL query. It may contain wildcards ($1, $2...) or (?, ?...).
• values: array of values if query contains wildcards
• options:
  • transaction
  • log: if false, logging is disabled for this particular call
  • silent_fail: can be true (will return undefined as query results) or false (default, exception will be propagated).

Returns an array of objects with the result of the query.

async connection.executeAndCount(query, values, options)

• query: string with SQL query. It may contain wildcards ($1, $2...) or (?, ?...).
• values: array of values if query contains wildcards
• options:
  • transaction
  • log: if false, logging is disabled for this particular call

Returns an integer with the number of rows affected by the query.

async connection.getTableNames(schema= 'public')

Returns an array with the table names present in the specified database schema:

Notice the results of this method will be in-memory cached: so query runs just once per connection.

async connection.getTableDetails(tableName, schema= 'public')

Returns an object with the details of a database table definition, like:

{
  'field_name': {
      type     : <type identifier>,
      key      : <bool>,
      nullable : <bool>,
      default  : <default value>   
  },...
}

Notice the results of this method will be in-memory cached: so query runs just once per connection and table.

async connection.getModel(table_name, schema= 'public')

• table_name: name of a table which was included on options.tables value.

Returns a Model object.

Model object

In calustra, a Model object always refers to the database table; it never refers to a single record.

In other words: unlike other ORMs, you will not do const model= Model.create(); model.fieldA= 'value'; model.save(). In calustra you will do Model.insert({data}) or Model.update({data}, {filter}).

model.insert(data, options)

• data: an object with "what to insert". Fields that do not exist on Model definition will be discarded.
• options:
  • transaction: an calustra transaction object

It returns an int with the .id of the newly created record.

model.update(data, filter, options)

• data: an object with "what to update". Fields that do not exist on Model definition will be discarded.
• filter: an object with "which records to update". Fields that do not exist on Model definition will be discarded.
• options:
  • transaction: an calustra transaction object

It returns an int with the number of affected records by the update.

model.delete(filter, options)

• filter: an object with "which records to delete". Fields that do not exist on Model definition will be discarded.
• options:
  • transaction: an calustra transaction object

It returns an int with the number of deleted records.

model.read(filter, options)

• filter: an object with "which records to read". Fields that do not exist on Model definition will be discarded.
• options:
  • fields: a subset of table's field names to include on the result output
  • sortby: indicates wat field to sort by the read. It may be an string with the field's name (sort will be ASC), or a two elements Array like [field_name, ASC|DESC]
  • limit and offset: to make paginated reads
  • transaction: an calustra transaction object

It returns an Array of objects, empty if no record was found with the specified filter.

model.find(id, options)

• id: an int with the .id to look for
• options:
  • transaction: an calustra transaction object

It returns an object with the desired record, empty if none was found.

Query tools

At calustra/query these are a small -yet powerful- set of utils over SQL queries.

getTableNamesFromQuery (query)

Returns an array of the table names involved in query.

removeComments (query)

Cleans comments from query.

cleanAndInline (query)

Cleans comments from query, also compacting it in a single line if multiline.

queryMainAction (query)

Checks what the main action of the query is, even for the hard ones. Possible return values are: create, alter, drop, insert, update, delete, select.

queryDescription (query, rows, time)

Returns a human readable description of the query.

Examples:

• Created table cars (time: <time>)
• Inserted <rows> rows into cars (time: <time>)

formatQuery (qry, params)

Clean and colorize a query with logging in mind.

Notes

Cached connections

Notice that calustra keeps a simple cache of connections once they are initialized. You can get them using getConnection(selector):

import {getConnection} from 'calustra'
const conn = await getConnection(`calustra`)

selector is just a string matching some part of the config you passed the first time to init the connection.

Closing a connection destroys and uncaches it, but closing connections must be done carefully:

conn.close()

You can disable caching of a connection by specifying the option cache: false:

const conn = await getConnection(config, {cache: false})
// connection will not be available later trough getConnection(selector)

When creating a connection, you may force to re-init it (and ignore previous cached connection, if any) by specifying the option reset:

const conn = await getConnection(config, {reset: true})
// previous cached connection will be ignored and overwritten

Closing connections

If you close a connection:

connection.close()

notice that the database's pool will be removed, being no longer available. Even if recreating the Connection object you will get errors.

So, use it with care!

Changelog

0.11.0

Upgraded cacheiro to 0.1.1:

• getConnection is now async.
• added options.cache to customize calustra's cache usage
• removed options.nocache accordingly (now it is cache: false)