✨ (Flask-SQLAlchemy) Add info on schema updates and conclusion lecture

Author: jslvtr

docs/docs/06_sql_storage_sqlalchemy/02_create_simple_sqlalchemy_model/README.md

@@ -29,6 +29,7 @@ class ItemModel(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(80), unique=True, nullable=False)
     price = db.Column(db.Float(precision=2), unique=False, nullable=False)
+    store_id = db.Column(db.Integer, unique=False, nullable=False)
 ```
 
 ```python title="models/store.py"

docs/docs/06_sql_storage_sqlalchemy/02_create_simple_sqlalchemy_model/end/models/item.py

@@ -7,3 +7,4 @@ class ItemModel(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(80), unique=True, nullable=False)
     price = db.Column(db.Float(precision=2), unique=False, nullable=False)
+    store_id = db.Column(db.Integer, unique=False, nullable=False)

docs/docs/06_sql_storage_sqlalchemy/02_create_simple_sqlalchemy_model/end/schemas.py

@@ -1,26 +1,18 @@
 from marshmallow import Schema, fields
 
 
-class PlainItemSchema(Schema):
-    id = fields.Int(dump_only=True)
+class ItemSchema(Schema):
+    id = fields.Str(dump_only=True)
     name = fields.Str(required=True)
     price = fields.Float(required=True)
-
-
-class PlainStoreSchema(Schema):
-    id = fields.Int(dump_only=True)
-    name = fields.Str()
-
-
-class ItemSchema(PlainItemSchema):
-    store_id = fields.Int(required=True, load_only=True)
-    store = fields.Nested(lambda: PlainStoreSchema(), dump_only=True)
+    store_id = fields.Int(required=True)
 
 
 class ItemUpdateSchema(Schema):
     name = fields.Str()
     price = fields.Float()
 
 
-class StoreSchema(PlainStoreSchema):
-    items = fields.List(fields.Nested(PlainItemSchema()), dump_only=True)
+class StoreSchema(Schema):
+    id = fields.Str(dump_only=True)
+    name = fields.Str(required=True)

docs/docs/06_sql_storage_sqlalchemy/02_create_simple_sqlalchemy_model/start/schemas.py

@@ -1,26 +1,18 @@
 from marshmallow import Schema, fields
 
 
-class PlainItemSchema(Schema):
-    id = fields.Int(dump_only=True)
+class ItemSchema(Schema):
+    id = fields.Str(dump_only=True)
     name = fields.Str(required=True)
     price = fields.Float(required=True)
-
-
-class PlainStoreSchema(Schema):
-    id = fields.Int(dump_only=True)
-    name = fields.Str()
-
-
-class ItemSchema(PlainItemSchema):
-    store_id = fields.Int(required=True, load_only=True)
-    store = fields.Nested(lambda: PlainStoreSchema(), dump_only=True)
+    store_id = fields.Int(required=True)
 
 
 class ItemUpdateSchema(Schema):
     name = fields.Str()
     price = fields.Float()
 
 
-class StoreSchema(PlainStoreSchema):
-    items = fields.List(fields.Nested(PlainItemSchema()), dump_only=True)
+class StoreSchema(Schema):
+    id = fields.Str(dump_only=True)
+    name = fields.Str(required=True)

docs/docs/06_sql_storage_sqlalchemy/03_one_to_many_relationships_sqlalchemy/README.md

@@ -72,4 +72,49 @@ And here's how you would do some filtering:
 
 ```python
 store.items.filter_by(name=="Chair").first()
+```
+
+## Updating our marshmallow schemas
+
+Now that the models have these relationships, we can modify our marshmallow schemas so they will return some or all of the information about the related models.
+
+We do this with the `Nested` marshmallow field.
+
+:::caution
+Something to be careful about is having schema A which has a nested schema B, which has a nested schema A.
+
+This will lead to an infinite nesting, which is obviously never what you want!
+:::
+
+To avoid infinite nesting, we are renaming our schemas which _don't_ use nested fields to `Plain`, such as `PlainItemSchema` and `PlainStoreSchema`.
+
+Then the schemas that _do_ use nesting can be called `ItemSchema` and `StoreSchema`, and they inherit from the plain schemas. This reduces duplication and prevents infinite nesting.
+
+```python title="schemas.py"
+from marshmallow import Schema, fields
+
+
+class PlainItemSchema(Schema):
+    id = fields.Int(dump_only=True)
+    name = fields.Str(required=True)
+    price = fields.Float(required=True)
+
+
+class PlainStoreSchema(Schema):
+    id = fields.Int(dump_only=True)
+    name = fields.Str()
+
+
+class ItemSchema(PlainItemSchema):
+    store_id = fields.Int(required=True, load_only=True)
+    store = fields.Nested(lambda: PlainStoreSchema(), dump_only=True)
+
+
+class ItemUpdateSchema(Schema):
+    name = fields.Str()
+    price = fields.Float()
+
+
+class StoreSchema(PlainStoreSchema):
+    items = fields.List(fields.Nested(PlainItemSchema()), dump_only=True)
 ```

docs/docs/06_sql_storage_sqlalchemy/03_one_to_many_relationships_sqlalchemy/start/models/item.py

@@ -7,3 +7,4 @@ class ItemModel(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(80), unique=True, nullable=False)
     price = db.Column(db.Float(precision=2), unique=False, nullable=False)
+    store_id = db.Column(db.Integer, unique=False, nullable=False)

docs/docs/06_sql_storage_sqlalchemy/10_conclusion/README.md

@@ -0,0 +1,103 @@
+---
+title: Conclusion of this section
+description: Review everything we've changed this section to add SQL storage with SQLAlchemy to our API.
+---
+
+# Conclusion of this section
+
+Adding SQL storage to our app has required quite a few changes! Let's do a quick review.
+
+## Installed SQLAlchemy and Flask-SQLAlchemy
+
+```
+pip install sqlalchemy flask-sqlalchemy
+```
+
+And
+
+```text title="requirements.txt"
+sqlalchemy
+flask-sqlalchemy
+```
+
+## Created models
+
+```python title="models/item.py"
+from db import db
+
+
+class ItemModel(db.Model):
+    __tablename__ = "items"
+
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String(80), unique=True, nullable=False)
+    price = db.Column(db.Float(precision=2), unique=False, nullable=False)
+
+    store_id = db.Column(
+        db.Integer, db.ForeignKey("stores.id"), unique=False, nullable=False
+    )
+    store = db.relationship("StoreModel", back_populates="items")
+```
+
+And
+
+```python title="models/store.py"
+from db import db
+
+
+class StoreModel(db.Model):
+    __tablename__ = "stores"
+
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String(80), unique=True, nullable=False)
+
+    items = db.relationship("ItemModel", back_populates="store", lazy="dynamic")
+```
+
+## Updated resources to use SQLAlchemy
+
+Previously we were using Python dictionaries as a database. Now we've swapped them out for using SQLAlchemy models by:
+
+- Importing the models in our resource files
+- Retrieving models from the database with `ModelClass.query.get_or_404(model_id)`.
+- Updating models by changing attributes, or creating new model class instances, and then saving and committing with `db.session.add(model_instance)` and `db.session.commit()`.
+- Deleting models with `db.session.delete(model_instance)` followed by `db.session.commit()`.
+
+## Updated marshmallow schemas
+
+Since now our models have relationships, that means that the schemas can have `Nested` fields.
+
+The schemas that don't have `Nested` fields we've called "Plain" schemas, and those that do are named after the model they represent.
+
+```python title="schemas.py"
+from marshmallow import Schema, fields
+
+
+class PlainItemSchema(Schema):
+    id = fields.Int(dump_only=True)
+    name = fields.Str(required=True)
+    price = fields.Float(required=True)
+
+
+class PlainStoreSchema(Schema):
+    id = fields.Int(dump_only=True)
+    name = fields.Str()
+
+
+class ItemSchema(PlainItemSchema):
+    store_id = fields.Int(required=True, load_only=True)
+    store = fields.Nested(PlainStoreSchema(), dump_only=True)
+
+
+class ItemUpdateSchema(Schema):
+    name = fields.Str()
+    price = fields.Float()
+
+
+class StoreSchema(PlainStoreSchema):
+    items = fields.List(fields.Nested(PlainItemSchema()), dump_only=True)
+```
+
+And that's it! Quite a few changes, but hopefully you're still with me.
+
+In the following sections we'll be adding more functionality to our API, so stay tuned!