Question

I’m needing to implement an API for my Flask application and have seen recommendations for Flask-Restless. I’ve run in to kind of a wall with just basic usage of this library and hoping someone who has used it can assist.

Creating the API manager and endpoints…

manager = APIManager(app, flask_sqlalchemy_db=db)
manager.create_api(Gallery, methods=['GET', 'POST', 'PUT', 'DELETE'])

…and the model that goes with that

class Gallery(db.Model):
    __tablename__ = 'galleries'
    id = db.Column(db.Integer, primary_key=True)

    title = db.Column(db.String(25))

    def __init__(self, title):
        self.title = title

Now, to insert new entries, I use this jQuery ajax POST request. This works fine. I’ve tested it in a sqlite db viewer and can see the entries.

$('#form').on('submit', function(e){
        $.ajax({
            type: 'post',
            url: '/api/galleries',
            contentType:"binary/octet-stream",
            data: JSON.stringify({'title': $('#title').val()}),
            success: function(){
                alert('Success!');
            }
        });
        e.preventDefault();
    });

Here’s the issue. I go to http://localhost:5000/api/galleries in my browser and get the following message:

sqlalchemy.orm.exc.NoResultFound
NoResultFound: No row was found for one()

Its odd it would try to run one() when api/galleries should return a list of db entries. I try api/galleries/1 and get the exact same error. I double checked and the primary id is 1. What am I missing?

Answer 1

I got the same issue today and solved it with some workaround.

Here is what my models look like:

    class User(db.Model):
        id = db.Column(db.Integer, primary_key=True)
        ...

    class Key(db.Model):
        user_id = db.Column(db.Integer, db.ForeignKey('auth_user.id'))
        user = db.relationship('User', backref=db.backref('keys', lazy='dynamic'))
        ...

Cause:

I got the same error message when querying users. And I found that flask-restless is trying to query the related keys for my users and unfortunately, my key table is empty and I got the error message.

Workaround:

Use include_columns or exclude_columns to exclude the keys column when creating APIs:

    api_mgr.create_api(User, include_columns = ['email', 'username'])

or:

    api_mgr.create_api(User, exclude_columns = ['keys', 'SOME_OTHER_COLUMNS'])

You can check out if there is any related tables causing the problem. And if it is the cause, you can using include_columns or exclude_columns keyword arguments.