Package Exports

mongodb-schema

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Readme

mongodb-schema

Infer a probabilistic schema for a MongoDB collection.

Example

mongodb-schema doesn't do anything directly with mongodb so to try the examples we'll install the node.js driver. As well, we'll need some data in a collection to derive the schema of:

npm install mongodb mongodb-schema.
mongo --eval "db.test.insert([{_id: 1, a: true}, {_id: 2, a: 'true'}, {_id: 3, a: 1}, {_id: 4}])" localhost:27017/test
Create a new file parse-schema.js and paste in the following code:

var parseSchema = require('mongodb-schema');
var connect = require('mongodb');

connect('mongodb://localhost:27017/test', function(err, db){
  if(err) return console.error(err);

  parseSchema('test.test', db.collection('test').find(), function(err, schema){
    if(err) return console.error(err);

    console.log(JSON.stringify(schema, null, 2));
    db.close();
  });
});

When we run the above with node parse-schema.js, we'll see something like the following:

{
  ns: 'test.test',
  count: 4, // The number of documents sampled
  fields: [ // A collection of Field objects @see lib/field.js
    {
      name: "_id",
      probability: 1, // Just as we expected, all 4 documents had `_id`
      unique: 4, // All 4 values for `_id` were unique
      types: [
        {
          name: "Number", // The only type seen was a Number
          probability: 1,
          unique: 4
        }
      ]
    },
    {
      name: "a", // Unlike `_id`, `a` was present in only 3 of 4 documents
      probability: 0.75,
      unique: 3, // Of the 3 values seen, all 3 were unique
      // As expected, Boolean, String, and Number values were seen.
      // A handy instance of `Undefined` is also provided to represent missing data",
      "types": [
        {
          name: "Boolean",
          probability: 0.25,
          unique: 1
        },
        {
          name: "String",
          probability: 0.25,
          unique: 1
        },
        {
          name: "Number",
          probability: 0.25,
          unique: 1
        },
        {
          name: "Undefined",
          probability: 0.25
        }
      ]
    }
  ]
}

More Examples

mongodb-schema supports all BSON types. Checkout the tests for more usage examples.

Installation

npm install --save mongodb-schema

Testing

npm test

License

Apache 2.0

Contributing

Under the hood, mongodb-schema uses ampersand-state and ampersand-collection for modeling Schema, Field's, and Type's.

A high-level view of the class interactions is as follows: