mysql-events

mysql-events

A Node JS NPM package that watches a MySQL database and runs callbacks on matched events.

This package is based on the ZongJi node module. Please make sure that you meet the requirements described at ZongJi, like MySQL binlog etc.

#Quick Start

var MySQLEvents = require('mysql-events');
var dsn = {
  host:     _dbhostname_,
  user:     _dbusername_,
  password: _dbpassword_,
};
var mysqlEventWatcher = MySQLEvents(dsn);
var watcher =mysqlEventWatcher.add(
  'myDB.table.field.value',
  function (oldRow, newRow, event) {
     //row inserted
    if (oldRow === null) {
      //insert code goes here
    }

     //row deleted
    if (newRow === null) {
      //delete code goes here
    }

     //row updated
    if (oldRow !== null && newRow !== null) {
      //update code goes here
    }

    //detailed event information
    //console.log(event)
  }, 
  'match this string or regex'
);

#Installation

npm install mysql-events

#Usage

• Import the module into your application

var MySQLEvents = require('mysql-events');

• Instantiate and create a database connection

var dsn = {
  host:     'localhost',
  user:     'username',
  password: 'password'
};
var myCon = MySQLEvents(dsn);

Make sure the database user has the privilege to read the binlog on database that you want to watch on.

• Use the returned object to add new watchers

var event1 = myCon.add(
  'dbName.tableName.fieldName.value',
  function (oldRow, newRow, event) {
    //code goes here
  }, 
  'Active'
);

This will listen to any change in the fieldName and if the changed value is equal to Active, then triggers the callback. Passing it 2 arguments. Argument value depends on the event.

• Insert: oldRow = null, newRow = rowObject
• Update: oldRow = rowObject, newRow = rowObject
• Delete: oldRow = rowObject, newRow = null

###rowObject It has the following structure:

{
  database: dbName,
  table: tableName,
  affectedColumns: {
    [{
      name:     fieldName1,
      charset:  String,
      type:     Number
      metedata: String
    },{
      name:     fieldName2,
      charset:  String,
      type:     Number
      metedata: String
    }]
},{
  changedColumns: [fieldName1, fieldName2],
  fields: {
   fieldName1: recordValue1,
   fieldName2: recordValue2,
     ....
     ....
     ....
   fieldNameN: recordValueN
  }
}

##Remove an event

event1.remove();

##Stop all events on the connection

myCon.stop();

##Additional options In order to customize the connection options, you can provide your own settings passing a second argument object to the connection function.

var mysqlEventWatcher = MySQLEvents(dsn, {
  startAtEnd: false // it overrides default value "true"
});

You can find the list of the available options here.

#Watcher Setup Its basically a dot '.' seperated string. It can have the following combinations

• database: watches the whole database for changes (insert/update/delete). Which table and row are affected can be inspected from the oldRow & newRow
• database.table: watches the whole table for changes. Which rows are affected can be inspected from the oldRow & newRow
• database.table.column: watches for changes in the column. Which database, table & other changed columns can be inspected from the oldRow & newRow
• database.table.column.value: watches for changes in the column and only trigger the callback if the changed value is equal to the 3rd argument passed to the add().
• database.table.column.regexp: watches for changes in the column and only trigger the callback if the changed value passes a regular expression test to the 3rd argument passed to the add(). The 3rd argument must be a Javascript Regular Expression Object, like, if you want to match for a starting sting (eg: MySQL) in the value, use /MySQL/i. This will trigger the callback only if the new value starts with MySQL

#LICENSE MIT