All of the tests should pass, and I've tested moving an app from using Potion w/o Blueprints to Blueprints with no apparent adverse effects.

Note: One change here is that Api.__init__ now joins unnamed routes with _ rather than . (see https://github.com/refgenomics/potion/blob/blueprints/flask_potion/init.py#L159-L162) if the Api is initialized with a Blueprint. This should potentially be simplified to always use _ (. does not work with Blueprints).

Caveats: I have not experimented with registering the same Blueprint multiple times (and if that has any unintended consequences) or registering multiple Blueprints (which this comment indicates may require a few changes https://github.com/biosustain/potion/blob/master/flask_potion/init.py#L83).

Closes #12.

@lyschoening – would appreciate your review and any further suggested changes.

fix: check to avoid BinaryExpression raising TypeError: Boolean value of this clause is not defined

When updating a value to NULL, the expression get_value('location', item, None) != value evaluates to get_value('location', item, None) != None. The result, in case the value in db isn't NULL, is a IS NOT NULL BinaryExpression.

As documented in here, under such circumstances, using <class 'sqlalchemy.sql.elements.BinaryExpression'> as python operator raises TypeError: Boolean value of this clause is not defined.

Trying my hand at a peewee backend for potion. The only part I haven't figured out is the relation_add and relation_remove methods. Peewee supports many-to-many relations using a playhouse extension, which is currently implemented. But for one-to-many, for example, the relation_* methods appear to be implemented in a reverse manner to what peewee expects. For example:

class User(Model):
    parent = ForeignKeyField('self', null=True, related_name='children')
    name = CharField()

You can't do:

parent = User.create(name='foo')
child = User.create(name='bar')
parent.children.add(child)

Instead you would do:

child.parent = parent

But relation_add/relation_remove only provide the item attribute and not the target attribute. So I'd have to figure out a way to get that attribute via peewee in some way. Haven't found a way to do this yet.

Check if there is no content before aborting the request.

This fixes issues with posts to endpoints that have no parameters i.e.

@routes.ItemRoute.POST('/mark_read')
    def mark_read(self, move_task) -> fields.DateTimeString():
        move_task.mark_read()
        return move_task.seen_at

Without this fix, you'd have one of two issues:

>> http POST :5000/v2/move_tasks/667/mark_read 'Authorization: Bearer '(cat mtoken) 'Content-type: application/json'
HTTP/1.0 400 BAD REQUEST
Content-Length: 111
Content-Type: application/json
Date: Tue, 16 May 2017 19:57:03 GMT
Server: Werkzeug/0.12.1 Python/3.6.1

{
    "message": "Failed to decode JSON object: Expecting value: line 1 column 1 (char 0)",
    "status": 400
}

>> http POST :5000/v2/move_tasks/667/mark_read 'Authorization: Bearer '(cat mtoken)
HTTP/1.0 415 UNSUPPORTED MEDIA TYPE
Content-Length: 60
Content-Type: application/json
Date: Tue, 16 May 2017 19:57:09 GMT
Server: Werkzeug/0.12.1 Python/3.6.1

{
    "message": "Unsupported Media Type",
    "status": 415
}

I want to define an Object with patternProperties, basically to return a schema-free dict.

Looking at the doc it seems you'd do this with fields.Object(pattern_properties={'.*': MyValueSchema}), but this just returns a dict with ".*" as key.

What's the correct way of defining an object with patternProperties?

Even though I protect the generated API with authentication, the schema endpoints remain open:

decorators = [jwt_authentication_dec]
api_blueprint = Blueprint('api', __name__)
api = Api(api_blueprint, decorators=decorators, default_manager=principals(SQLAlchemyManager))

Any GET to http://example.com/api/schema or http://example.com/api/res/schema return the schema.

Addresses #72. Second commit if you don't want ItemUri filters on by default @lyschoening (I'd lean towards leaving this on for consistency with $id handling and because, well, otherwise users may run into it and think filtering is broken – but up to you, using a custom manager here anyhow)

~I'm not 100% thrilled by the naming/implementation here (happy to take suggestions @lyschoening), but~ the current Flask-Potion code can lead to odd bugs for databases that do not guarantee the return order for queries without an ORDER BY clause (e.g., Postgres).

Specifically, we were seeing issues where we'd get duplicate records in the paginated results. The underlying issue is (depending on one's perspective) either a bug or (under/mis)documentation in Flask-SQLAlchemy's paginate method on the query.

This PR fixes this for the RelationalManager by ordering by the primary key if no other order by clause is provided.

Note that it may be necessary to also add the primary key to the order clause in the general _query_order_by call for Postgres. I'll try to investigate this more tomorrow Pacific time.

I have this resource:

class Goods(ModelResource):
    class Meta:
        name = 'goods'
        model = dal.Good
        include_id = True

    class Schema:
        category = fields.ToOne('good_categories')

If I send GET request to http://localhost:5000/goods, response doesn't contain Links and X-Total-Countheaders.

in instances.py there is some code like this:

class PaginationMixin(object):
  def format_response(self, data):
        if not isinstance(data, self._pagination_types): 
            return self.format(data) # always RETURN THIS, break rest of the method
        .... 

Currently, the PrincipalsMixin supports generating a UserNeed based on a ToOne reference field, e.g., user:owner.

It doesn't, however, seem to let you restrict access to generate a similar UserNeed for restricting access to a User resource directly.

Locally, I've hacked a solution that simply supports other field types here. Unfortunately, the downstream checks assume that the field has a resource attribute, which requires adding the resource onto the ItemUri field (whether at init or in the need method calls) or changing them.

Any thoughts on the most elegant solution @lyschoening? Happy to submit a PR if this is wanted/useful functionality.

@lyschoening, it seems that filtering on datetime columns are not possible right now, is that correct? And do you agree that this is a project issue that should be fixed?

How can we define a custom attribute for instances?

Using this route as example:

    @ItemRoute.GET
    def is_recent(self, book) -> fields.Boolean():
        return datetime.date.today().year <= book.year_published + 10

How can we define is_recent at the instances level such as: http GET :5000/book/1 would return book attributes containing is_recent: True | False as well

In order to reduce the amount of data being transferred from a resource, is it possible to provide a query args to return a set of fields? Sometimes, we don't need all attributes of an object but a couple of them. It would require too many custom routes to expose the different set of attributes we would need. Here a few examples to describe it:

/users?include_fields=['first_name', 'last_name']
/users?include_fields=['email']
/users?include_fields=['city', 'country']

by running the example peewee_simple.py as is, I get

$ python peewee_simple.py
Traceback (most recent call last):
  File "peewee_simple.py", line 42, in <module>
    api.add_resource(BookResource)
  File "/home/m/.local/share/virtualenvs/pano-vehicle-version-config-api-JCsed19j/lib/python3.6/site-packages/flask_potion/__init__.py", line 215, in add_resource
    resource.manager = self.default_manager(resource, resource.meta.get('model'))
  File "/home/m/.local/share/virtualenvs/pano-vehicle-version-config-api-JCsed19j/lib/python3.6/site-packages/flask_potion/contrib/peewee/manager.py", line 26, in __init__
    super(PeeweeManager, self).__init__(resource, model)
  File "/home/m/.local/share/virtualenvs/pano-vehicle-version-config-api-JCsed19j/lib/python3.6/site-packages/flask_potion/manager.py", line 27, in __init__
    self._init_model(resource, model, resource.meta)
  File "/home/m/.local/share/virtualenvs/pano-vehicle-version-config-api-JCsed19j/lib/python3.6/site-packages/flask_potion/contrib/peewee/manager.py", line 63, in _init_model
    if column.primary_key or name in model._meta.rel:
AttributeError: 'Metadata' object has no attribute 'rel'