mysql-stream-db

Streaming MySQL ORM

npm install mysql-stream-db
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mysql-stream-db

API

Base

DB

Table


base.connect(options)

This is shorthand for establishing a mysql connection and connecting to it. See the linked page for the connection options.

Returns a db object


db.registerTable(localName, options)

Registers a table against the internal table cache. Note, this does not create the table in the database (nor does it run any SQL at all).

localName is the name the table will be registered under. You can use this later with connection.table() to get a handle for the table.

options

  • primaryKey: the primary key for the table. Defaults to id
  • tableName: the name of the table in the actual database. Defaults to localName
  • fields: an array representing all the fields this table has. Example: ['id', 'first_name', 'last_name', 'created_at']
  • methods: methods to add to a row object as it gets emitted from the database. this in the function context will be a reference to the row. Example:
db.registerTable('friendship', {
  fields: [ 'id', 'screen_name', 'friend' ],
  methods: {
    hifive: function hifive() {
      return this.screen_name + ' deserves a hifive!'
    }
  }
})

Returns a table object.


db.table(localName)

Return a previously registered table. If the table is not in the internal cache, db.table will throw an error.

Returns a table object.


table.put(row, callback)

Inserts or updates a single row.

An insert will always be attempted first. If the insert fails with an ER_DUP_ENTRY and the row contains the table's primaryKey, an update will be attempted

callback will receive two arguments: err, result. Result should have three properties, row, sql, and insertId. If the result of a put() is an update, the result will have affectedRows instead of insertId.


table.get(conditions, options, callback)

Gets some a single row from the table.

conditions

conditions can be in one of two forms: simple or explicit

Simple:

albums.get({
  artist: 'Hookworms',
  album: 'Teen Dream'
}, function(err, rows){ ... })

Explicit:

albums.get({
  artist: {
    value: 'Hookworms',
    operation: '=',
  },
  release_year: {
    operation: '<=',
    value: 2012
  }
}, function(err, rows){ ... })

You can also mix and match the types and use arrays:

Mixed

albums.get({
  artist: 'David Bowie',
  release_year: [{
    operation: '>=',
    value: 1976
  }, {
    operation: '<='
    value: 1978
  }]
}, function(err, rows){ ... })

(NOTE: arrays not yet implemented)

Currently all of the conditions are inclusive – the where statement is joined with AND – so the row must match all of the parameters to be included.

options

  • sort: TODO: implement
  • limit: TODO: implement
  • page: TODO: implement

table.del(conditions, options, callback)

Deletes rows from the database.

Be careful – you can truncate an entire table with this command.

garbage.del({}, function(err){
  // garbage is now empty.
})
  • conditions: see above
  • options:
    • limit: maximum number of rows to delete

table.createReadStream(conditions, options)

Create a ReadStream for the table.

pause() and resume()

pause() and resume() will operate on the underlying connection and you are guaranteed to not receive anymore data events after calling pause() (according to the documentation)

Events

  • data: Receives one argument, row.
  • error: If there is an error, it will be emitted here.
  • end: When the stream is complete.

options.relationships

You can define relationships on the data coming out of the stream. This will translate to JOINs at the SQL layer, so you can (potentially) see some performance gains versus populating manually.

options.relationships is an object, keyed by property. The property name will be used when attaching the foreign rows to the main row. This will also be used as the source of the foreign key relationship unless a from property is defined.

  • table: the name of the foreign table. This should be a string that can be used with db.table() to look up the table cache.
  • type: Either "hasOne" or "hasMany".
  • foreign: The foreign column to match against.
  • from: If the key name doesn't correspond to a local column, from should be used to specify it. Optional
  • optional: Whether or not the relationship is optional (INNER vs LEFT join). Defaults to false.
  • pivot: This is necessary as a hint to help properly aggregate "hasMany" relationships. Foreign rows will be stored as an array on the current main row until pivot column on the main row changes. At that point the foreign rows will start aggregating against the new main row.
Example

user table

id handle name location
1 brianloveswords brian brooklyn
2 mozilla mozilla the internet

food table

id user_id text
1 1 tacos
2 1 pizza
3 2 burritos
4 2 fries
5 1 salmon
user.createReadStream({}, {
  relationships: {
    food: {
      table: 'food',
      type: 'hasMany',
      foreign: 'user_id',
      from: 'id',
      pivot: 'id',
    }
  }
})

This would emit two rows:

// row 1
{ id: 1,
  handle: 'brianloveswords',
  name: 'brian',
  location: 'brooklyn',
  food: [
    { id: 1, user_id 1,  text: 'tacos' },
    { id: 2, user_id 1,  text: 'pizza' },
    { id: 5, user_id 1,  text: 'salmon' },
  ]
}

// row 2
{ id: 2,
  handle: 'mozilla',
  name: 'mozilla',
  location: 'the internet',
  food: [
    { id: 3, user_id 2, text: 'burittos'},
    { id: 4, user_id 2, text: 'fries' }
  ]
}

table.createKeyStream(conditions)

Emits a data event for each row with just the primary key of that row.

See above for definition of conditions


table.createWriteStream(options)

Creates a WriteStream to the table.

The write() method on the stream takes row data. When a row is successfully written, a meta event is emitted and passed a meta object containing row, sql and insertId

An internal buffer is not kept, so all calls to write()s will return false to signal a ReadStream to pause(). Once a row has been succesfully stored, a drain event will be emitted.

If options.ignoreDupes, any duplicate key errors will be ignored instead of emitting an error event. Ignored rows will be emitted as dupe events.

Example

const ws = band.createWriteStream()

ws.on('error', function (err) {
  console.log('Oh my!', err)
})

ws.on('close', function () {
  console.log('Done!')
})

ws.write({ name: 'Brian', instrument: 'bass', food: 'burritos' })
ws.write({ name: 'Jeremy', instrument: 'drums', food: 'cheese' })
ws.write({ name: 'Travis', instrument: 'bass', food: 'tofu' })
ws.end()
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