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https://github.com/koopjs/koop-provider-mongo

A mongo db provider for koop
https://github.com/koopjs/koop-provider-mongo

koop-provider

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A mongo db provider for koop

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# koop-provider-mongo



Provider to fetch data from a MongoDb instance.  It can access any database/collection on your instance by assigning the `id` route-parameter a delimited value in the form of `database-name::collection-name`.



## Data considerations

As per MongoDB specifications, [each document/record in your dataset will have a unique-identifier](https://www.mongodb.com/docs/manual/core/document/#the-_id-field), `_id`.  At insert time, you can choose to assign this value manually, or allow Mongo to generate it automatically. In terms of your provider metadata, this means that you could always use `_id` as the value of your provider's `idField` (an attribute used to flag which GeoJSON property is the unique-identifier).



If your data has a geometry, you should consider using [geospatial index](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-geospatial/).  While not necessary, it will likely speed any queries including a geometry operation.



## Usage



Register the provider with Koop:



```js

const Koop = require('@koopjs/koop-core');

const koop = new Koop({ logLevel: 'info'});

const mongoProvider = require('@koopjs/provider-mongodb');



koop.register(mongoProvider, { connnectString, databases });

```



### Registration/Config parameters

The provider can be configured with registration options or the use of the `config` module with an entry key `"mongodb"` in the JSON configuration document.  See below, for an example of using the `config` approach 



#### `connectString`: string

A MongoDB connection string, e.g., `mongodb://localhost:27017`. 



#### `databases`: object

A key/value populated object that serves as a metadata lookup/dictionary for any database/collection on your MongoDB instance that you wish to provide access.  For example, if imagine you have a database called `db1` and it has a collection called `my-collection`.  You can set up the `databases` object so as to provide metadata for `my-collection`:



```js

{

  db1: {

    'my-collection': {

      geometryField: 'location', // field holding a record's GeoJSON geometry.

      idField: '_id', // field to treat as the unique-id.  Default: `_id`.

      cacheTtl: 0, // number of seconds to cache results from MongoDb. Default: 0.

      crs: 4326, // Coordinate reference system of geometry. Default: 4326.

      maxRecordCount: 2000, // Max number of records to return in a page. Default: 2000.

    }

  }

}

```



Note that for each collection, you may configure the options above.  If you do not assign a field to `geometryField`, the collection will be treated like tabular data, and the GeoJSON generated will have no geometry,



#### `definedCollectionsOnly`: boolean

This setting determines if the database/collection must appear in the `databases` parameter to be accessed. Defaults to `true`.



#### Setting with the "config" module

Koop allows providers to use the [`config` module](https://github.com/node-config/node-config). The settings above can be stored in a config JSON under the key `mongodb`:



```json

{

  "mongodb": {

      "connectString": "mongodb://localhost:27017",

      "databases": {

        "cdf-sample-data": {

          "fires": {

            "geometryField": "location",

            "idField": "_id",

            "cacheTtl": 0,

            "crs": 4326,

            "maxRecordCount": 2000

          }

        }

      }

  }

}

```



## Route parameters



#### `id`

Once registered with Koop, the provide will expose routes with an `id` parameter. For example:



```sh

/mongodb/rest/services/:id/FeatureServer

```



The `id` parameter should be filled with a `::` delimited string with the target `::`.  For example, a request like:



```sh

/mongodb/rest/services/sample-db::fires/FeatureServer/0/query

```



would return records from the `fires` _collection_ in the `sample-db` _database_. 



## Demo



The repository includes a demonstration project.  To run the demo you will need Docker installed on your computer. Once installed you can following the steps below to create a local Elastic instance and load it with sample data:



```sh

> npm install



> cd demo



# use Docker to run Elastic/Kibana

> docker-compose up -d



# load sample data; this will create an MongoDB database called "sample-data' with a collection named "fires"

> node loader.js 



# start the Koop application

> node index.js

```