loopback-connector-couch

CouchDB connector for Loopback.io. Heavily borrowing from the original CouchDB-nano adapter for jugglingdb by Nicholas Westlake and Anatoliy Chakkaev, but adapted/partially rewritten for use with Loopback.io. You need to have CoffeeScript if you want to adapt it.

Compilation

Use grunt to produce end file in ./lib. Else, use directly the provided version or modify Gruntfile as you need.

Working with your database

Upon initialisation, you can specify different authorisations, and up to 3 different connections will be established to the database: one for reader, one for writer and one for admin (see below why you need an admin one).

Usage

To use it you need to load the loopback-connector-juggler first if used programmatically, as any other connector. Otherwise, set things up in your datasources.json (see Loopback.io documentation for details):

"YOURDATASOURCENAME": {
	"name": "YOURDATASOURCENAME",	//Loopback.io - mandatory
	"connector": "couch",			//Loopback.io - mandatory
	"db": "DBNAME",					//"db" or "database" - required
	"host": "127.0.0.1",			//this is also the default if not included
	"port": 5984,					//this is also the default if not included
	"protocol": "http",				//this is also the default if not included
	"auth": {						//optional, including each of its members
			"admin": {
				"username": "YOURUSERNAME_ADMIN",
				"password": "YOURPASSWORD_ADMIN"
			},
			"reader": {
				"username": "YOURUSERNAME_READER",
				"password": "YOURPASSWORD_READER"
			},
			"writer": {
				"username": "YOURUSERNAME_WRITER",
				"password": "YOURPASSWORD_WRITER"
			}
	},
	"views": [						//optional
		{
			"ddoc": "existing_design_document",
			"name": "existing_design_document_view"
		},
		...
	]
}

Automatic creation of views for indexes

This adapter will automatically a number of design documents on your database:

1. \_design/loopback document contains by_model view that maps documents to their model name (set as property in the model as "loopbackModel"). To do so, authorisation enabled to modify design documents is required in the parameters if the CouchDB server is not in party mode.
2. For each model that has at least one property with index: true it will create one design document named \_design/loopback_<modelName> and one view named by_<propertyName> for each indexed property. Again, authorisation enabled to modify design documents is required.
3. Additional views can be queried if appropriately set up at initialization in the views option.

Automatic use of created views

During querying of database for standard Loopback.io API endpoints this adapter will:

1. Try to automatically leverage the views it created if an indexed property is used in where.
2. Fallback to using loopback/by_model view to reduce the number of documents it has to load and scan.

Query parameters and other details

• All queries to the database use include_docs set to true
• Loopback's offset is used as skip query parameter
• Loopback's limit is used as limit query parameter
• Both offset and limit are ignored in the request if a specific id is requested via where (e.g. {"where": {"id":"someID"}}). If where is included (e.g. {"where":{"foo":"bar"}}), then the results are retrieved in their entirety, then filtered via where and then offset and limit, so that for example all items that satisfy the where criteria can be retrieved in various paginated requests.

Known caveats

• queryView API endpoint (only generated if the options specify additional views to be made available in the CouchDB database) will return the output of the view (with specific keys as requested), that may or may not be linked to the Model being used for the query, if the same CouchDB database is used for multiple document types: fundamentally, no checks are done on the output of the view (other than any _id into id and removing loopbackModel property in case present).
• PUT /modelName/{id} | updateAttributes API endpoint will work as expected, but will not return the updated _rev (working to solve that issue). Consider updating the entire document via PUT /modelName, as that will allow to update the _rev in the response.

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.