How to add to a list type in Python Eve without replacing old values

Question

I have a very similar setup to the person in this question: How do I update a list data_relation in Python Eve with a users resource and a friends sub-resource of list type.

Answer 1

POST will allow you to add a new document to the users endpoint. If it is returning a 405 then you most likely need to enable the POST method by adding it to the RESOURCE_METHODS list, as all endpoints are read-only by default; see docs (alternatively you can only enable POST for the individual endpoint by adding the method to the local resource_methods instead.)

PATCH allows for the replacing of individual fields (as opposed to PUT, which will replace the whole document). So with PATCH you can atomically update the friends list by replacing it with a new value (a new list ObjectIds in your case), but you cannot push a single new ObjectId inside the existing list, I am afraid.

Answer 2

Here is the workaround that I used. It's probably not the most efficient way to do this, but it worked for me.

Instead of having a users/friends list like I had originally planned, I ended up creating a resource for shares. In my case, I wanted to know which crystals were shared with which users. So when I query crystals/<crystal_id>/shares, I should get a list of the shares for that crystal.

I think you could apply a solution like this to the users/friends scenario if you swap crystals for users and shares for friends. You might put two different user_id data_relations in your friends_schema (my shares_schema).

shares_schema = {
    'crystal_id': {
        'type': 'objectid',
        'required': True,
        'data_relation': {
            'resource': 'crystals',
            'embeddable': True,
        },
    },
    'user_id': {
        'type': 'objectid',
        'required': True,
        'data_relation': {
            'resource': 'users',
            'embeddable': True,
        },
    },
}

shares = {
    'internal_resource': True,
    'schema': shares_schema,
}

crystals_shares = {
    'schema': shares_schema,
    'url': 'crystals/<regex("[a-f0-9]{24}"):crystal_id>/shares',
    'datasource': {'source': 'shares'},
}