Hey thanks a ton!
On Thu, Oct 22, 2020 at 8:26 PM Simon King <[email protected]> wrote:
> So FinishedGoods is connected to FinishedGoodsChild through the
> goods_child_sizes table? You haven't provided a definition of that
> table, so I'm going to guess it's something like this:
>
> goods_child_sizes = db.Table(
> 'goods_child_sizes',
> db.Column('parent_id', db.Integer,
> db.ForeignKey('finished_goods.id'), primary_key=True),
> db.Column('child_id', db.Integer,
> db.ForeignKey('finished_goods_child.id'), primary_key=True),
> )
>
> If so, then your hybrid property would look something like:
>
> @balance.expression
> def balance(cls):
> condition = sa.and_(
> FinishedGoodsChild.id == goods_child_sizes.c.child_id,
> goods_child_sizes.c.parent_id == cls.id,
> )
> return select([sa.func.sum(FinishedGoodsChild.qty)]).\
> where(condition).\
> label('balance')
>
> (You'll have to fix those column names to match your real
> goods_child_sizes table)
>
> Simon
>
> On Thu, Oct 22, 2020 at 2:41 PM Padam Sethia <[email protected]>
> wrote:
> >>
> >>
> >> class FinishedGoodsChild(TimestampMixin, db.Model):
> >>
> >> id = db.Column(db.Integer, primary_key=True)
> >>
> >> hold_qty = db.Column(db.Float, default=0)
> >> pen_qty = db.Column(db.Float, default=0)
> >> qty = db.Column(db.Float, nullable=False, default=0)
> >> sku = db.Column(db.String(40), nullable=False, default='')
> >> size = db.relationship('SizeMaster',
> >> secondary='size_goods_child',
> passive_deletes=True, backref='size_goods_child', lazy='joined')
> >>
> >> size_id = db.Column(db.Integer, nullable=False, default=None)
> >>
> >> def __init__(self, qty, sku, size):
> >> self.qty = qty
> >> self.sku = sku
> >> self.size_id = size.id
> >> self.size.append(size)
> >>
> >>
> >> db.Table('size_goods_child',
> >>
> >> db.Column('size_id', db.Integer, db.ForeignKey(
> >> 'size_master.id', ), primary_key=True, nullable=False
> >> ),
> >> db.Column('goods_id', db.Integer, db.ForeignKey(
> >> 'finished_goods_child.id', ), primary_key=True,
> nullable=False
> >> )
> >> )
> >>
> >>
> >> class FinishedGoodsChildSchema(ma.ModelSchema):
> >> id = field_for(FinishedGoodsChild, 'id', dump_only=True)
> >> qty = field_for(FinishedGoodsChild, 'qty', dump_only=True)
> >> hold_qty = field_for(FinishedGoodsChild, 'hold_qty', dump_only=True)
> >> pen_qty = field_for(FinishedGoodsChild, 'pen_qty', dump_only=True)
> >> sku = field_for(FinishedGoodsChild, 'sku', dump_only=True)
> >>
> >> size = ma.Nested(SizeMasterSchema, many=True)
> >>
> >> class meta:
> >> model = FinishedGoodsChild
> >>
> >>
> >> db.Table('hsn_goods',
> >> db.Column('hsn_id', db.Integer, db.ForeignKey(
> >> 'hsn.id', ), primary_key=True, nullable=False
> >> ),
> >> db.Column('goods_id', db.Integer, db.ForeignKey(
> >> 'finished_goods.id', ), primary_key=True, nullable=False
> >> )
> >> )
> >>
> >> class FinishedGoods(SearchableMixin, TimestampMixin, db.Model):
> >> __searchable__ = ['balance','created', 'updated', 'title',
> 'description', 'sku','qty',
> >> 'product_category', 'fabric_combination',
> 'print_technique', 'design_number']
> >>
> >> id = db.Column(db.Integer, primary_key=True)
> >>
> >> filter_tags = db.relationship(
> >> 'FilterTags', passive_deletes=True,
> secondary='filter_tags_goods', backref='filter_tags_goods', lazy='joined')
> >> product_category = db.relationship(
> >> 'ProductCategory', passive_deletes=True,
> secondary='product_category_goods', backref='product_category_goods',
> lazy='joined')
> >> fabric_combination = db.relationship(
> >> 'FabricCombination', passive_deletes=True,
> secondary='fabric_combination_goods', backref='fabric_combination_goods',
> lazy='joined')
> >> print_technique = db.relationship(
> >> 'PrintTechnique', passive_deletes=True,
> secondary='print_technique_goods', backref='print_technique_goods',
> lazy='joined')
> >> design_number = db.relationship(
> >> 'DesignNumber', passive_deletes=True,
> secondary='design_number_goods', backref='design_number_goods',
> lazy='joined')
> >> uom = db.relationship('Uom',
> >> secondary='uom_goods', passive_deletes=True,
> backref='uom_goods', lazy='joined')
> >> hsn = db.relationship('Hsn',
> >> secondary='hsn_goods', passive_deletes=True,
> backref='hsn_goods', lazy='joined')
> >> size = db.relationship('SizeMaster',
> >> secondary='size_goods',
> passive_deletes=True, backref='size_goods', lazy='joined')
> >>
> >> size_chart = db.relationship('SizeChart',
> >> secondary='size_chart_goods',
> passive_deletes=True, backref='size_chart_goods', lazy='joined')
> >>
> >> # Foreign Key IDs for Unique Constraint
> >>
> >> product_category_id = db.Column(db.Integer, nullable=False)
> >> fabric_combination_id = db.Column(db.Integer, nullable=False)
> >> print_technique_id = db.Column(db.Integer, nullable=False)
> >> design_number_id = db.Column(db.Integer, nullable=False)
> >> uom_id = db.Column(db.Integer, nullable=False)
> >> size_id = db.Column(db.Integer, nullable=False, default=None)
> >> # End FK
> >> title = db.Column(db.String(100), nullable=False)
> >> description = db.Column(db.String(250), nullable=False)
> >>
> >> price = db.Column(db.Float, nullable=False, default="0")
> >> qty = db.Column(db.Float, nullable=False)
> >> hold_qty = db.Column(db.Float, default=0)
> >> pen_qty = db.Column(db.Float, default=0)
> >>
> >> gst = db.Column(db.Integer, nullable=False, default="0")
> >> multiple = db.Column(db.Integer, nullable=False, default=1)
> >> sku = db.Column(db.String(40), nullable=False)
> >>
> >> image = db.Column(db.String(250))
> >>
> >> children = db.relationship('FinishedGoodsChild',
> >> passive_deletes=True,
> secondary='goods_child_sizes', backref='goods_child_sizes', lazy='joined')
> >> balance = db.Column(db.Float , default= 0)
> >>
> >> __table_args__ = (db.UniqueConstraint(
> >> 'product_category_id', 'fabric_combination_id',
> 'print_technique_id', 'design_number_id', 'sku',
> name='finished_goods_chk_id'), )
> >>
> >> def __init__(self, product_category, fabric_combination,
> print_technique, design_number, uom, size, title, description, sku, price,
> qty, multiple):
> >> self.product_category_id = product_category.id
> >> self.product_category.append(product_category)
> >>
> >> self.fabric_combination_id = fabric_combination.id
> >> self.fabric_combination.append(fabric_combination)
> >>
> >> self.print_technique_id = print_technique.id
> >> self.print_technique.append(print_technique)
> >>
> >> self.design_number_id = design_number.id
> >> self.design_number.append(design_number)
> >>
> >> self.uom_id = uom.id
> >> self.uom.append(uom)
> >>
> >> self.size_id = size.id
> >> self.size.append(size)
> >>
> >> self.title = title
> >> self.description = description
> >> self.price = price
> >> self.qty = qty
> >> self.multiple = multiple
> >> self.sku = sku
> >>
> >> def get_gen_name(self):
> >> goods_name = "{}/{}/{}/{}".format(
> >> self.product_category[0].name,
> self.fabric_combination[0].name, self.print_technique[0].name,
> self.design_number[0].name)
> >> return goods_name
> >
> >
> > On Thu, Oct 22, 2020 at 3:53 PM Simon King <[email protected]>
> wrote:
> >>
> >> You don't need to add a parent_id column, you just need to write the
> >> full relationship condition inside that "select" statement. It would
> >> be much easier to explain if you can show your actual parent and child
> >> classes, including the relationship between them and the association
> >> table.
> >>
> >> Simon
> >>
> >> On Thu, Oct 22, 2020 at 7:23 AM Padam Sethia <[email protected]>
> wrote:
> >> >
> >> > Thanks for your input , the children have a many to many relationship
> with the parent FinishedGoods , with this how would I refer to parent_id ,
> do i need to create and add that also ?
> >> >
> >> > On Wed, 21 Oct 2020, 14:48 Simon King, <[email protected]>
> wrote:
> >> >>
> >> >> The "expression" part of a hybrid property is used whenever you write
> >> >> "FinishedGoodsParent.balance". It operates in the context of the
> >> >> class, not a single instance, and it needs to return an SQL
> expression
> >> >> that can be used inside a larger query.
> >> >>
> >> >> In your version, you are trying to iterate over "cls.children", but
> >> >> that's not possible because "cls.children" is not a list. Hybrid
> >> >> properties that work across relationships can be a bit difficult to
> >> >> think about. The expression that you return needs to access another
> >> >> table, so you need to consider how the query will join to that table:
> >> >>
> >> >>
> https://docs.sqlalchemy.org/en/13/orm/extensions/hybrid.html#working-with-relationships
> >> >>
> >> >> In your case, you actually need to perform an aggregating function
> >> >> (sum) on the related table. The easiest way to do that would be to
> >> >> follow the correlated subquery example from the docs:
> >> >>
> >> >>
> https://docs.sqlalchemy.org/en/13/orm/extensions/hybrid.html#correlated-subquery-relationship-hybrid
> >> >>
> >> >> Something like this:
> >> >>
> >> >> @balance.expression
> >> >> def balance(cls):
> >> >> return select([sa.func.sum(FinishedGoodsChild.qty)]).\
> >> >> where(FinishedGoodsChild.parent_id==cls.id).\
> >> >> label('balance')
> >> >>
> >> >> You probably need something a bit more complicated than that - I
> >> >> didn't understand the join condition between parent and child in your
> >> >> example so I made up the "parent_id" column.
> >> >>
> >> >> Hope that helps,
> >> >>
> >> >> Simon
> >> >>
> >> >> On Tue, Oct 20, 2020 at 4:57 PM Padam Sethia <[email protected]>
> wrote:
> >> >> >
> >> >> > Hello ,
> >> >> >
> >> >> > I'm having an issue with Hybrid methods - I still don't understand
> them enough properly . So I have a parent and child many to many
> relationship
> >> >> >
> >> >> >
> >> >> > This is the child model
> >> >> >
> >> >> > class FinishedGoodsChild(TimestampMixin, db.Model):
> >> >> > id = db.Column(db.Integer, primary_key=True)
> >> >> > hold_qty = db.Column(db.Float, default=0)
> >> >> > pen_qty = db.Column(db.Float, default=0)
> >> >> > qty = db.Column(db.Float, nullable=False, default=0)
> >> >> > sku = db.Column(db.String(40), nullable=False, default='')
> >> >> > size = db.relationship('SizeMaster',
> secondary='size_goods_child', passive_deletes=True,
> backref='size_goods_child', lazy='joined')
> >> >> > size_id = db.Column(db.Integer, nullable=False, default=None)
> >> >> >
> >> >> > This is the Parent model
> >> >> >
> >> >> >
> >> >> > class FinishedGoodsChild(TimestampMixin, db.Model):
> >> >> > id = db.Column(db.Integer, primary_key=True)
> >> >> > qty = db.Column(db.Float, default=0)
> >> >> > balance = db.Column(db.Float)
> >> >> > children = db.relationship('FinishedGoodsChild',
> passive_deletes=True, secondary='goods_child_sizes',
> backref='goods_child_sizes', lazy='joined')
> >> >> >
> >> >> >
> >> >> > No I need to filter by the sum of the children qty
> >> >> >
> >> >> >
> >> >> > Here is the hybrid property that I have set up , but throws not
> implemented error
> >> >> >
> >> >> >
> >> >> > @hybrid_property
> >> >> > def balance(self):
> >> >> > return sum(acc.qty for acc in self.children) @balance.expression
> >> >> > def balance(cls):
> >> >> > return sum(acc.qty for acc in cls.children)
> >> >> >
> >> >> > Help is much appreciated thanks!
> >> >> >
> >> >> > --
> >> >> > SQLAlchemy -
> >> >> > The Python SQL Toolkit and Object Relational Mapper
> >> >> >
> >> >> > http://www.sqlalchemy.org/
> >> >> >
> >> >> > To post example code, please provide an MCVE: Minimal, Complete,
> and Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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> .
> >> >>
> >> >> --
> >> >> SQLAlchemy -
> >> >> The Python SQL Toolkit and Object Relational Mapper
> >> >>
> >> >> http://www.sqlalchemy.org/
> >> >>
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> >> >
> >> > --
> >> > SQLAlchemy -
> >> > The Python SQL Toolkit and Object Relational Mapper
> >> >
> >> > http://www.sqlalchemy.org/
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> >> SQLAlchemy -
> >> The Python SQL Toolkit and Object Relational Mapper
> >>
> >> http://www.sqlalchemy.org/
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> >
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> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
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>
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>
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