couchdb.rst

CouchDB and Pyramid

If you want to use CouchDB (via the CouchDB package) in Pyramid, you can use the following pattern to make your CouchDB database available as a request attribute. (This follows the same pattern as the :doc:`mongo` example.)

First add some hair to your development.ini file, including a CouchDB URI and a "db_name" (the CouchDB database name, can be anything).

 [app:myapp]
 # ... other settings ...
 couchdb_uri = http://user:password@localhost/
 db_name = myapp

Then in your __init__.py, set things up such that the database is attached to each new request:

 from pyramid.config import Configurator
 from pyramid.events import subscriber
 from pyramid.events import NewRequest

 import couchdb

 @subscriber(NewRequest)
 def add_couchdb_to_request(event):
     request = event.request
     settings = request.registry.settings
     db = settings['db_server'][settings['db_name']]
     event.request.db = db

 def main(global_config, **settings):
     config = Configurator(settings=settings)

     db_server = couchdb.client.Server(settings['couchdb_uri'])
     config.registry.settings['db_server'] = db_server

     config.add_route('home', '/')

     # other routes and more config...
     config.scan('myapp')

     return config.make_wsgi_app()

At this point, in view code, you can use request.db as the CouchDB database connection. For example:

 from pyramid.view import view_config

 @view_config(route_name='home', renderer="home.pt")
 def home_view(request):
     map_func = '''
         function(doc) {
         if (doc.type == 'MyDocumentType')
             emit(doc._id, doc);
         }'''
     documents = ((doc.key, doc.value) for doc in request.db.query(map_func))
     return {'documents': documents}

Permanent CouchDB Views

As per the CouchDB docs, once your ad-hoc CouchDB view functions are working correctly, you should move them into permanent views. For example, to create a CouchDB view at startup:

 from pyramid.events import ApplicationCreated

 DESIGN_DOC_ID = '_design/myapp'

 @subscriber(ApplicationCreated)
 def application_created_subscriber(event):
     settings = event.app.registry.settings
     server = settings['db_server']
     try:
         db = server[settings['db_name']]
     except couchdb.http.ResourceNotFound:
         db = server.create(settings['db_name'])

     # We'll create some couchdb views so we don't have to do ad-hoc queries.
     home_view_map_func = '''
       function(doc) {
       if (doc.type == 'MyDocumentType')
          emit(doc._id, doc);
       }'''
     design_doc = db.get(DESIGN_DOC_ID, {'_id': DESIGN_DOC_ID})
     design_doc.update({
         "language": "javascript",
         "views": {
             "home": {
                 "map": home_view_map_func,
                 },
             }
         })
     _id, rev = db.save(design_doc)
     log.info('Updated design doc: id %s, revision %s' % (_id, rev))

Then you can update your Pyramid view code to call that view:

 @view_config(route_name='home', renderer="home.pt")
 def home_view(request):
     view_id = '%s/_view/home' % DESIGN_DOC_ID
     documents = ((doc.key, doc.value) for doc in request.db.view(view_id))
     return {'documents': documents}