# Quick tutorial

We're going to build a simple todo app, to demonstrate the capabilities of the MycroForge CLI.
After this tutorial, you should have a solid foundation to start exploring and using MycroForge to develop your 
projects.

## General notes

The commands in this tutorial assume that you're running them from a MycroForge root directory.

## Initialize the project

Open a terminal and `cd` into the directory where your project should be created. 
Run `m4g init todo-app` to initialize a new project and open the newly created project by running `code todo-app`.
Make sure you have `vscode` on you machine before running this command. If you prefer using another editor, then 
manually open the generated `todo-app` folder.

## Setup the database

Our todo app needs to keep track of todos, so it needs a storage mechanism of some sorts. A database should be one
of the first things, if not THE first thing, that comes to mind. Luckily, MycroForge provides you with a locally hosted 
database for you project out of the box. This setup, is powered by docker compose and can be examined by opening the 
`db.docker-compose.yml` file in the project. Follow along to learn how to use the docker based database when developing
locally.

### Run the database

The first step is to start the database, you can do this by running the following command in a terminal.

`m4g db run`

This command starts the services defined in the `db.docker-compose.yml` file.
You can verify that the services are up by running `docker container ls`. If everything went well, then the previous
command should output the service names defined in `db.docker-compose.yml`.

If you go to [PhpMyAdmin (i.e. http://localhost:5051)](http://localhost:5051), you should now be able to login with the
following credentials.
- user: root
- pass: password

When you're done developing, you can shut down the local database by running `m4g db stop`


### Create the entities

Now that the database is running, we can start to create our entities. Run the commands below to create the `Todo` & 
`Tag` entities.

`m4g db generate entity Tag --column "description:str:String(255)"`

`m4g db generate entity Todo --column "description:str:String(255)" -c "is_done:bool:Boolean()"`

After running these commands, you should find the generated entities in the `db/entities` folder of your project.
You should also see that the `main.py` & `db/env.py` files have been modified to include the newly generated entity.

For more information about the `m4g db generate entity` command, you can run `m4g db generate entity -?`.

### Define a many-to-many relation between Todo & Tag

To allow for relations between `Todo` & `Tag`, we'll define a many-to-many relation between the two entities.
This relation makes sense, because a `Todo` can have many `Tags` and a `Tag` could belong to many `Todos`.
You can generate this relation by running the following command from you terminal.
Creating a one-to-many relation would also make sense, but for the purpose of demonstration we're going to demonstrate
the many-to-many relation, because this one is the most complex, since it requires an additional mapping to be included
in the database schema.

`m4g db link many Todo --to-many Tag`

After running this command you should see that both the `Todo` and `Tag` entities now have a new field referencing the
a `List` containing instances of the other entity.

For more information about the `m4g db link` command try running `m4g db link -?`. Note that you can do the same thing
for all sub commands, so if you want to know more about `m4g db link many` you can simply run `m4g db link many -?` to
examine the command. The same is true for all the other commands as well.

### Generate the migration

Now that we've generated our entities, it's time to generate a migration that will apply these changes in the database.
Generate the initial migration by running the following command.

`m4g db generate migration initial_migration`

After running this command, you should see the new migration in the `db/version` directory.

### Apply the migration

The last step for the database setup is to actually apply the new migration to the database. This can be done by running
the following command.

`m4g db migrate`

After running this command, you should now see a populated schema when visiting [PhpMyAdmin](http://localhost:5051).
If for whatever reason you want to undo the last migration, you can simply run `m4g db rollback`.

## Setup the API

### Generate CRUD for Tag & Todo

Our API should provide use with basic endpoint to manage the `Todo` & `Tag` entities, i.e. CRUD functionality.
Writing this code can be boring, since it's pretty much boilerplate with some custom additions sprinkled here and there.
Fortunately, MycroForge can generate a good chunk of this boring code on your behalf. Run the following commands to
generate CRUD functionality for the `Todo` & `Tag` classes.

`m4g api generate crud Tag`

`m4g api generate crud Todo`

After running this command you should see that the `api/requests`,`api/routers` & `api/services` now contain the
relevant classes need to support the generated CRUD functionality. This could should be relatively straightforward, so 
we won't dive into it, but feel free to take a break and explore what the generated code actually does. Another thing to
note, is that the generated routers are also automatically included in `main.py`.

### Modify the generated Todo request classes

Since we have a many-to-many relationship between `Todo` & `Tag`, the generated CRUD functionality isn't quite ready 
yet. We need to be able to specify which `Tags` to add to a `Todo` when creating or updating it.
To do this, we will allow for a `tag_ids` field in both the `CreateTodoRequest` & the `UpdateTodoRequest`. 
This field will contain the ids of the `Tags` that are associated with a `Todo`.

Modify `CreateTodoRequest` in `api/requests/create_todo_request.py`, you might need to import `List` from `typing`.

```python
# Before
class CreateTodoRequest(BaseModel):
    description: str = None
    is_done: bool = None
    
# After
class CreateTodoRequest(BaseModel):
    description: str = None
    is_done: bool = None
    tag_ids: Optional[List[int]] = []
```

Modify `UpdateTodoRequest` in `api/requests/update_todo_request.py`, you might need to import `List` from `typing`.

```python
# Before
class UpdateTodoRequest(BaseModel):
    description: Optional[str] = None
    is_done: Optional[bool] = None
    tag_ids: Optional[List[int]] = []

# After
class UpdateTodoRequest(BaseModel):
    description: Optional[str] = None
    is_done: Optional[bool] = None
    tag_ids: Optional[List[int]] = []
```

### Modify generated TodoService

The `TodoService` will also need to be updated to accomodate the management of `tag_ids`. 

Add the following imports in `api/services/todo_service.py`.

```python
from sqlalchemy.orm import selectinload
from db.entities.tag import Tag
```

Modify `TodoService.list`

```python
# Before
    async with async_session() as session:
        stmt = select(Todo)
        results = (await session.scalars(stmt)).all()
        return results

# After
    async with async_session() as session:
        stmt = select(Todo).options(selectinload(Todo.tags))
        results = (await session.scalars(stmt)).all()
        return results
```

Modify `TodoService.get_by_id`

```python
# Before
    async def get_by_id(self, id: int) -> Optional[Todo]:
        async with async_session() as session:
            stmt = select(Todo).where(Todo.id == id)
            result = (await session.scalars(stmt)).first()
            return result

# After
    async def get_by_id(self, id: int) -> Optional[Todo]:
        async with async_session() as session:
            stmt = select(Todo).where(Todo.id == id).options(selectinload(Todo.tags))
            result = (await session.scalars(stmt)).first()
            return result
```

Modify `TodoService.create`

```python
# Before
    async def create(self, data: Dict[str, Any]) -> None:
        async with async_session() as session:
            entity = Todo(**data)
            session.add(entity)
            await session.commit()

# After
    async def create(self, data: Dict[str, Any]) -> None:
        tag_ids = []
    
        if "tag_ids" in data.keys():
            tag_ids = data["tag_ids"]
            del data["tag_ids"]
    
        async with async_session() as session:
            entity = Todo(**data)
    
            if len(tag_ids) > 0:
                stmt = select(Tag).where(Tag.id.in_(tag_ids))
                result = (await session.scalars(stmt)).all()
                entity.tags = list(result)
    
            session.add(entity)
            await session.commit()
```

Modify `TodoService.update`

```python
# Before
    async def update(self, id: int, data: Dict[str, Any]) -> bool:
        tag_ids = []
    
        if "tag_ids" in data.keys():
            tag_ids = data["tag_ids"]
            del data["tag_ids"]
    
        async with async_session() as session:
            stmt = select(Todo).where(Todo.id == id)
            entity = (await session.scalars(stmt)).first()
    
            if entity is None:
                return False
            else:
                for key, value in data.items():
                    setattr(entity, key, value)
                await session.commit()
                return True

# After
    async def update(self, id: int, data: Dict[str, Any]) -> bool:
        tag_ids = []
    
        if "tag_ids" in data.keys():
            tag_ids = data["tag_ids"]
            del data["tag_ids"]
    
        async with async_session() as session:
            stmt = select(Todo).where(Todo.id == id).options(selectinload(Todo.tags))
            entity = (await session.scalars(stmt)).first()
    
            if entity is None:
                return False
            else:
                for key, value in data.items():
                    setattr(entity, key, value)
    
                if len(tag_ids) > 0:
                    stmt = select(Tag).where(Tag.id.in_(tag_ids))
                    result = (await session.scalars(stmt)).all()
                    entity.tags = list(result)
                else:
                    entity.tags = []
    
                await session.commit()
                return True
```

At this point, the app should be ready to test.
TODO: Elaborate!