MongoDB Query function

The MondoDB Query Function allows the creation of a function to perform an MLDB SQL query against a MongoDB collection. It is similar to the SQL Query function.

Caveat

• mongodb.dataset will not work on collections having key "_id" that are not ObjectIDs. See MongoDB ObjectID
• Some less popular BSON types are not supported. See BSON Types -- Regular Expression -- DBPointer -- JavaScript -- JavaScript (with scope) -- Min key -- Max key

Configuration

A new function of type mongodb.query named <id> can be created as follows:

mldb.put("/v1/functions/"+<id>, {
    "type": "mongodb.query",
    "params": {
        "uriConnectionScheme": <string>,
        "collection": <string>,
        "output": <SqlQueryOutput>
    }
})

with the following key-value definitions for params:

Example

For this example, we will use a MongoDB database populated with data provided by the book MongoDB In Action. The zipped json file is available at http://mng.bz/dOpd.

Here we create the query function on the MongoDB zips database zips collection.

mldb.put("/v1/functions/mongo_query", {
    "type": "mongodb.query",
    "params": {
        "connectionScheme": 'mongodb://somehost.mldb.ai:11712/zips',
        "collection": 'zips'
    }
})

A direct call to the function looks like

import json
mldb.get('/v1/functions/mongo_query/application',
    input={'query' : json.dumps({'zip' : {'$eq' : '60623'}})}
).json()

With the output

{
    'output': {
        '_id': u'57d2f5eb21af5ee9c4e22302',
        'city': 'CHICAGO',
        'loc': [['x', [87.7157, '2016-09-09T17:48:27Z']],
                ['y', [41.849015, '2016-09-09T17:48:27Z']]],
        'pop': 112047,
        'state': 'IL',
        'zip': '60623'
    }
}

Here is an example of the function beign used within a query.

mldb.query("""
    SELECT mongo_query({query: '{"loc.x" : {"$eq" : 73.968312}}'}) AS *
""")