mungedb-aggregate

mungedb-aggregate

A JavaScript data aggregation pipeline based on the MongoDB database's aggregation framework.

Based on the MongoDB C++ code (v2.4.0).

Updating to v2.6 soon.

Why

MongoDB Aggregation and JavaScript are both awesome. We put them together.

Now, with the ease of JavaScript and the power of the MongoDB aggregation pipeline, we can provide a single API for data munging, regardless of where execution occurs. You can extend the base functionality to suit your needs.

Example

var aggregate = require("mungedb-aggregate");

var inputs = [
  {v: 1},
  {v: 2},
  {v: 3},
  {v: 4},
  {v: 5}
];

var pipeline = [
  {$match:{
    v: {$gte: 3}
  }},
  {$project:{
    v2: {$multiply: ["$v", "$v"]}
  }}
];

aggregate(pipeline, inputs);  // => [{v2:9}, {v2:16}, {v2:25}]

API

Public parts:

• aggregate(pipeline, [inputs], [callback]) - The data aggregator
  • pipeline - The aggregation pipeline to apply to inputs
  • [inputs] - The input Objects to aggregate or return curried if omitted
  • [callback] - The callback if needed (for extensions using async calls)
• version - The MongoDB version that this code represents
• gitVersion - The MongoDB git revision that this code represents

Inner workings:

• Cursor - Used to go thru data (by PipelineD and CursorDocumentSource)
• pipeline
  • Pipeline - The pipeline handler
  • PipelineD - The pipeline data reader helper
  • FieldPath - Represents a path to a field within a document
  • Document - Document helpers used throughout the code
  • Value - Value helpers used throughout the code
  • accumulators - The Accumulator classes (used in $group)
  • documentSources - The DocumentSource classes (upper pipeline objects)
  • expressions - The Expression classes (used in $project)