platform/README.md

# orm
[![Pub](https://img.shields.io/pub/v/angel_orm.svg)](https://pub.dartlang.org/packages/angel_orm)
[![build status](https://travis-ci.org/angel-dart/orm.svg)](https://travis-ci.org/angel-dart/orm)

Source-generated PostgreSQL ORM for use with the
[Angel framework](https://angel-dart.github.io).
Now you can combine the power and flexibility of Angel with a strongly-typed ORM.

* [Usage](#usage)
* [Model Definitions](#models)
* [MVC Example](#example)
* [Relationships](#relations)
* [Columns (`@Column(...)`)](#columns)
    * [Column Types](#column-types)
    * [Indices](#indices)
    * [Default Values](#default-values)

# Usage
You'll need these dependencies in your `pubspec.yaml`:
```yaml
dependencies:
  angel_orm: ^1.0.0-alpha
dev_dependencies:
  angel_orm_generator: ^1.0.0-alpha
  build_runner: ^0.5.0
```

`package:angel_orm_generator` exports three classes that you can include
in a `package:build` flow:
* `PostgresOrmGenerator` - Fueled by `package:source_gen`; include this within a `LibraryBuilder`.
* `MigrationGenerator` - Builds a [`package:angel_migration`](https://github.com/angel-dart/migration) migration for your models automatically.
* `SqlMigrationBuilder` - This is its own `Builder`; it generates a SQL schema, as well as a SQL script to drop a generated table.

You should pass an `List<String>` containing your project's models.

# Models
Your model, courtesy of `package:angel_serialize`:

```dart
library angel_orm.test.models.car;

import 'package:angel_framework/common.dart';
import 'package:angel_orm/angel_orm.dart';
import 'package:angel_serialize/angel_serialize.dart';
part 'car.g.dart';

@serializable
@orm
class _Car extends Model {
  String make;
  String description;
  bool familyFriendly;
  DateTime recalledAt;
}
```

Models can use the `@Alias()` annotation; `package:angel_orm` obeys it.

After building, you'll have access to a `Query` class with strongly-typed methods that
allow to run asynchronous queries without a headache.

**IMPORTANT:** The ORM *assumes* that you are using `package:angel_serialize`, and will only generate code
designed for such a workflow. Save yourself a headache and build models with `angel_serialize`:

https://github.com/angel-dart/serialize

# Example

MVC just got a whole lot easier:

```dart
import 'package:angel_framework/angel_framework.dart';
import 'package:postgres/postgres.dart';
import 'car.dart';
import 'car.orm.g.dart';

/// Returns an Angel plug-in that connects to a PostgreSQL database, and sets up a controller connected to it...
AngelConfigurer connectToCarsTable(PostgreSQLConnection connection) {
  return (Angel app) async {
    // Register the connection with Angel's dependency injection system.
    // 
    // This means that we can use it as a parameter in routes and controllers.
    app.container.singleton(connection);
    
    // Attach the controller we create below
    await app.configure(new CarController(connection));
  };
}

@Expose('/cars')
class CarController extends Controller {
  // The `connection` will be injected.
  @Expose('/recalled_since_2008')
  carsRecalledSince2008(PostgreSQLConnection connection) {
    // Instantiate a Car query, which is auto-generated. This class helps us build fluent queries easily.
    var cars = new CarQuery();
    cars.where
      ..familyFriendly.equals(false)
      ..recalledAt.year.greaterThanOrEqualTo(2008);
    
    // Shorter syntax we could use instead...
    cars.where.recalledAt.year <= 2008;
    
    // `get()` returns a Stream.
    // `get().toList()` returns a Future.
    return cars.get(connection).toList();
  }
  
  @Expose('/create', method: 'POST')
  createCar(PostgreSQLConnection connection) async {
    // `package:angel_orm` generates a strongly-typed `insert` function on the query class.
    // Say goodbye to typos!!!
    var car = await CarQuery.insert(connection, familyFriendly: true, make: 'Honda');
    
    // Auto-serialized using code generated by `package:angel_serialize`
    return car;
  }
}
```

# Relations
`angel_orm` supports the following relationships:

* `@HasOne()`
* `@HasMany()`
* `@BelongsTo()` (one-to-one)

The annotations can be abbreviated with the default options (ex. `@hasOne`), or supplied
with custom parameters (ex. `@HasOne(foreignKey: 'foreign_id')`).

```dart
@serializable
@orm
abstract class _Author extends Model {
  @hasMany // Use the defaults, and auto-compute `foreignKey`
  List<Book> books;
  
  // Also supports parameters...
  @HasMany(localKey: 'id', foreignKey: 'author_id', cascadeOnDelete: true)
  List<Book> books;
  
  @Alias('writing_utensil')
  @hasOne
  Pen pen;
}
```

The relationships will "just work" out-of-the-box, following any operation. For example,
after fetching an `Author` from the database in the above example, the `books` field would
be populated with a set of deserialized `Book` objects, also fetched from the database.

Relationships use joins when possible, but in the case of `@HasMany()`, two queries are used:
* One to fetch the object itself
* One to fetch a list of related objects

# Columns
Use a `@Column()` annotation to change how a given field is handled within the ORM.

## Column Types
Using the `@Column()` annotation, it is possible to explicitly declare the data type of any given field:

```dart
@serializable
@orm
abstract class _Foo extends Model {
  @Column(type: ColumnType.BIG_INT)
  int bar;
}
```

## Indices
Columns can also have an `index`:

```dart
@serializable
@orm
abstract class _Foo extends Model {
  @Column(index: IndexType.PRIMARY)
  String bar;
}
```

## Default Values
It is also possible to specify the default value of a field.
**Note that this only works with primitive objects.**

If a default value is supplied, the `SqlMigrationBuilder` will include
it in the generated schema. The `PostgresOrmGenerator` ignores default values;
it does not need them to function properly.

```dart
@serializable
@orm
abstract class _Foo extends Model {
  @Column(defaultValue: 'baz')
  String bar;
}
```