mongo-web-handler/mongo-web-handler.js

This a helper for creating ExpressJS Web Handler for MongoDB querying.

/**
 * This helper provides a route handler function generator for expressJs server.
 * This handler execute a function querying MongoDB et returns the JSon result
 * in the response
 *
 * @module mongo-web-handler
 * @author Sébastien LANDEAU
 */
var Q = require('q');


/**
 * Provides a query result callback
 * with promise for mongoDB.
 *
 * @class MongoFutureResult
 * @constructor
 */
function MongoFutureResult( ){

  this.expectedResult = Q.defer();

  this.getFuture = function (){
    return this.expectedResult;
  }

  this.execCallback = function ( err, docs ){
    if( err ){
      this.expectedResult.reject(err);
      return;
    }
    this.expectedResult.resolve( docs );
    return;
  }
}


var moduleCorpus ={

    /**
     * Returns this model's attributes as...
     *
     * @method createMongoWebHandler
     * @return {function} ExpressJS web handler
     */
     createMongoWebHandler: function( logger, name, queryFunc ){



      // Closure
      function handler( req, res, next ){

        var results = new MongoFutureResult();
        var callb = results.execCallback.bind( results );

        // Querying
        logger.info( "On [%s], executing '%s'", req.path, name );

        // Call query functions
        queryFunc( req, res, callb );

        // Wait for results
        results.getFuture().promise
          .then( function(data){
            logger.info("> Mongo query '%s' ==> %d result(s)", name, data.length);
            res.status(200).json( data );
          })
          .fail( function(err){
            logger.error("> Mongo.query '%s', error : ", name, err);
            res.status(500).json({ status: "error", reason: err});
          });
      };

      return handler;
    }
}


/*
================================================================================

 EXPORTS

================================================================================
*/
module.exports = moduleCorpus;