mungedb-aggregate/lib/index.js

"use strict";
module.exports = (function(){

	/**
	 * Used to aggregate `inputs` using a MongoDB-style `pipeline`
	 *
	 * If `inputs` is given, it will run the `inputs` through the `pipeline` and call the `callback` with the results.
	 * If `inputs` is omitted, it will return an "aggregator" function so you can reuse the given `pipeline` against various `inputs`.
	 *
	 * NOTE: you should be mindful about reusing the same `pipeline` against disparate `inputs` because document coming in can alter the state of it's `DocumentSource`s
	 *
	 * @method aggregate
	 * @namespace mungedb
	 * @module mungedb-aggregate
	 * @param pipeline  {Array}  The list of pipeline document sources in JSON format
	 * @param [inputs]  {Array}  Optional inputs to pass through the `docSrcs` pipeline
	 * @param callback               {Function}                                 Called when done
	 * @param   callback.err           {Error}                                    The Error if one occurred
	 * @param   callback.docs          {Array}                                    The resulting documents
	 **/
	exports = function aggregate(pipeline, inputs, callback) {	// function-style interface; i.e., return the utility function directly as the require
		var ctx = {}, //not used yet
			pipelineInst = exports.pipeline.Pipeline.parseCommand({
				pipeline: pipeline
			}, ctx),
			aggregator = function aggregator(inputs, callback) {
				if (!callback) throw new Error("arg `callback` is required");
				if (!inputs) return callback("arg `inputs` is required");

				// rebuild the pipeline on subsequent calls
				if (!pipelineInst) {
					pipelineInst = exports.pipeline.Pipeline.parseCommand({
						pipeline: pipeline
					}, ctx);
				}

				// use or build input src
				var src;
				if(inputs instanceof exports.pipeline.documentSources.DocumentSource){
					src = inputs;
				}else{
					try{
						pipelineInst.collectionName = inputs;	//NOTE: use the given `inputs` directly; not really a "name" but we don't really have collection names in mungedb-aggregate
						src = exports.pipeline.PipelineD.prepareCursorSource(pipelineInst, pipelineInst.ctx);
					}catch(err){
						return callback(err);
					}
				}

				// run the pipeline against the input src
				return pipelineInst.run(src, function aggregated(err, results){
					pipelineInst = null; // unset so that subsequent calls can rebuild the pipeline
					if(err) return callback(err);
					return callback(null, results.result);
				});
			};
		if(inputs) return aggregator(inputs, callback);
		return aggregator;
	};

	exports.aggregate = exports;	// package-style interface; i.e., return a function underneath of the require

	//Expose these so that mungedb-aggregate can be extended.
	exports.Cursor = require("./Cursor");
	exports.pipeline = require("./pipeline/");

	// version info
	exports.version = "r2.4.0-rc0";
	exports.gitVersion = "cb8efcd6a2f05d35655ed9f9b947cc4a99ade8db";

	return exports;
})();