连接两个表，其中一个表具有不同的外键

Question

I'm attempting to join two tables together, however, I keep receving the errors of:

sqlalchemy.exc.InvalidRequestError: Could not find a FROM clause to join from. Tried joining to , but got: Can't find any foreign key relationships between 'recipe' and 'ingredient'.

and

sqlalchemy.exc.NoForeignKeysError: Can't find any foreign key relationships between 'recipe' and 'ingredient'.

class Recipe(db.Model):
    query_class = RecipeQuery
    __tablename__ = 'recipe'

    id = db.Column(db.Integer, primary_key=True)

    name = db.Column(db.Text)
    description = db.Column(db.Text)
    directions = db.Column(db.Text)
    prep_time = db.Column(db.String(15))
    cook_time = db.Column(db.String(15))
    image = db.Column(db.Text)
    ingredients = db.relationship('Ingredient', secondary=ingredients)
    credit = db.Column(db.String)

    search_vector = db.Column(TSVectorType('name', 'description', 'directions'))

class Ingredient(db.Model):
    query_class = IngredientQuery
    __tablename__ = 'ingredient'

    id = db.Column(db.Integer, primary_key=True)
    original = db.Column(db.Text)
    name = db.Column(db.Integer, db.ForeignKey('ingredient_name.id'))
    amount = db.Column(db.String(10))
    unit = db.Column(db.String(20))
    modifiers = db.Column(db.Text)

    search_vector = db.Column(TSVectorType('original'))

ingredients = db.Table('ingredients',
    db.Column('recipe', db.Integer, db.ForeignKey('recipe.id')),
    db.Column('ingredient', db.Integer, db.ForeignKey('ingredient.id'))
    )

I've tried selecting the items three different ways, all fail with the same error.

try1 = db.session.query(models.Recipe).join(models.Ingredient, secondary=ingredients)
try2 = db.session.query(models.Recipe).join(models.Ingredient)
try3 = db.session.query(models.Recipe).join('ingredients')

It looks similar to the example given for a many-to-many relationship given at http://docs.sqlalchemy.org/en/rel_0_9/orm/relationships.html The only real difference being that Ingredient has a foreign key, which might be throwing it off? If so, I'm still not sure how to fix that issue.

Thanks

Answer 1

Does one of these work if you explicitly specify the relationship in the join?

db.session.query(models.Recipe).\
    join(models.Ingredient, models.Recipe.ingredients)

db.session.query(models.Recipe).\
    join(models.Recipe.ingredients)