IS NULL with REST API

[coleifer]

Looks to not be working.

[rammie]

+1 for a fix.

Since the api doesn't support negation, I'm guess that 'is' implies 'is null'. I needed this to work, so I hacked it in by overriding RestResource.process_query and treating the 'is' operator differently. Any thoughts around a better implementation?

    def process_query(self, query):
        ...
        # clean and normalize the request parameters
        for key in request.args:
            if '__' in key:
                expr, op = key.rsplit('__', 1)
                if op not in DJANGO_MAP:
                    expr = key
                    op = 'eq'
            else:
                expr = key
                op = 'eq'

            # OP_IS implies that the value is None
            if op == 'is':
                raw_filters[expr] = [(op, [None])]
            else:
                raw_filters.setdefault(expr, [])
                raw_filters[expr].append((op, request.args.getlist(key)))
        ...
        return query

[jmtoball]

The API supports negation, at least in the current version. But that does not change much here.
I did this similarly, but patched "null": OP_IS into the DJANGO_MAP and then also set the value to None if the operator is OP_IS.

The setting of the value to None and thus the override of process_query would probably not be necessary if db_value of a ForeignKey would return None for empty strings. Is that an option?

[rammie]

1. Sweet, I forgot that master now supports negation.
2. I thought about patching a different operator into the DJANGO_MAP but decided against it as the following usage would be confusing:

model.filter(field__null=False)

1. This issue isn't exactly related to ForeignKeys as any nullable column would run into it. Also, for nullable CharFields/TextFields, distinguishing between NULL and the empty string is important.

[prawn-cake]

Does anybody plan to fix it officially? It would be great to get rid of this ridiculous limitation.
Django suggests quite neat way to handle it using field__isnull=True like syntax.
But it seems that it isn't supported by DJANGO_MAP
It implies to use is=None or eq=None syntax for ORM querying or pretty weird Model.field >> None.
So we have to add some adapters for this case here.

# flask_peewee/rest.py

if '__' in key:
    expr, op = key.rsplit('__', 1)
    if op not in DJANGO_MAP:
        expr = key
        if op == 'isnull':
            op = 'is'
            # transform value and 'negated' flag here if needed
        else:
            op = 'eq'
    ....