mongo-sql/helpers/query/joins.js

A mongo-like interface for sql generation, postgres-style

/**
 * Query Helper: Joins
 */

var helpers = require('../../lib/query-helpers');
var conditionBuilder = require('../../lib/condition-builder');
var queryBuilder = require('../../lib/query-builder');
var utils = require('../../lib/utils');

var buildJoin = function(join, values, query){
  // Require a target
  if ( !join.target )
    throw new Error('Invalid join.target type `' + typeof join.target + '` for query helper `joins`');

  // Allow for strings or objects for join.on
  if ( !join.on || ( typeof join.on !== 'string' && typeof join.on !== 'object' ) )
    throw new Error('Invalid join.on type `' + typeof join.on + '` for query helper `joins`');

  var output = ( join.type ? ( join.type + ' ' ) : '' ) + "join ";

  if ( typeof join.target === 'object' ) output += '(' + queryBuilder( join.target, values ) + ') ';
  else {
    output += utils.quoteObject.apply( null, [
      join.target
    , join.schema
    , join.database
    ].filter( function( a ){ return !!a; }) ) + ' ';
  }

  if ( join.alias ) output += '"' + join.alias + '" ';

  if ( typeof join.on === 'string' ) output += 'on ' + join.on;
  else output += 'on ' + conditionBuilder( join.on, join.alias || join.target, values );

  return output;
};

helpers.register('joins', function(joins, values, query){
  if ( Array.isArray( joins ) ){
    return joins.map( function( join ){
      return buildJoin( join, values, query );
    }).join(' ');
  }

  if ( typeof joins === 'object' ) {
    return Object.keys( joins ).map(function( val ){
      // For objects, the key is the default alias and target
      if ( !joins[ val ].alias )  joins[ val ].alias = val;
      if ( !joins[ val ].target ) joins[ val ].target = val;

      return buildJoin( joins[ val ], values, query );
    }).join(' ');
  }

  throw new Error('Invalid type `' + typeof joins + '` for query helper `joins`');
});