Chaining queries in MongoEngine

flask, mongodb, mongoengine, python, rest

Solution

Since, mongoengine supports keyword arguments to the `objects` call, you can create a dictionary, with the keys as field_names, and values as field_values. And then use this dictionary while querying. For example:

query = {}

if 'name' in request.args:
    query['name'] = request.args['name']

if 'phone' in request.args:
    query['phone'] = request.args['phone']

if 'email' in request.args:
    query['email'] = request.args['email']

user = User.objects(**query)

The above is just a sample, you might want to add security measures, and maybe have a default query, depending on your app.

Problem

I'm implementing a REST API for a standard CRUD app. In one example, to get a list of users, clients can call: `GET api.site.com/users` (and optionally) `?name=x` `phone=x` `email=x` Passing the above optional parameters filters the users I search for. I'm trying to implement this logic in Python. I'm thinking of chaining sub-queries, like so: Given: `users = User.objects()` Then: ``` if 'name' in request.args: users = users.objects(name = request.args['name']) ``` And: ``` # List of users is smaller after filtering by name if 'phone' in request.args: users = users.objects(phone = request.args['phone']) ``` And: ``` # List of users is smaller after filtering by phone if 'email' in request.args: users = users.objects(email = request.args['email']) ``` But the method isn't available, and I can't find out how to do this by checking the MongoEngine API reference or User Guide or tutorial. What can I do to chain sub-queries in MongoEngine?

Original source