Merge pull request #2 from moufmouf/inheritance

Adding the "extends" method to the table class.

Author: moufmouf

README.md

@@ -182,3 +182,21 @@ $table->column('uuid')->string(36)->primaryKey();
 $table->column('uuid')->then()
       ->primaryKey(['uuid']);
 ```
+
+**Declare an inheritance relationship between 2 tables:**
+
+In SQL, there is no notion of "inheritance" like with PHP objects.
+However, a common way to model inheritance is to write one table for the base class (containing the base columns/properties) and then one table per extended class containing the additional columns/properties.
+Each extended table has **a primary key that is also a foreign key pointing to the base table**.
+
+```php
+$db->table('contacts')
+   ->id()
+   ->column('email')->string(50);
+
+$db->table('users')
+   ->extends('contacts')
+   ->column('password')->string(50);
+```
+
+The `extends` method will automatically create a primary key with the same name and same type as the extended table. It will also make sure this primary key is a foreign key pointing to the extended table.

src/FluidColumn.php

@@ -217,7 +217,7 @@ public function references(string $tableName, ?string $constraintName = null, st
         $referencedColumns = $table->getPrimaryKeyColumns();
 
         if (count($referencedColumns) > 1) {
-            throw new FluidSchemaException('You cannot reference a table with a premiray key on several columns using FluidSchema. Use DBAL Schema methods instead.');
+            throw new FluidSchemaException('You cannot reference a table with a primary key on several columns using FluidSchema. Use DBAL Schema methods instead.');
         }
 
         $referencedColumnName = $referencedColumns[0];

src/FluidTable.php

@@ -99,4 +99,21 @@ public function timestamps(): FluidTable
         $this->column('updated_at')->datetimeImmutable();
         return $this;
     }
+
+    public function extends(string $tableName): FluidTable
+    {
+        $inheritedTable = $this->schema->getDbalSchema()->getTable($tableName);
+
+        $pks = $inheritedTable->getPrimaryKeyColumns();
+
+        if (count($pks) > 1) {
+            throw new FluidSchemaException('You cannot inherit from a table with a primary key on several columns using FluidSchema. Use DBAL Schema methods instead.');
+        }
+
+        $pkName = $pks[0];
+        $pk = $inheritedTable->getColumn($pkName);
+
+        $this->column($pk->getName())->references($tableName)->primaryKey();
+        return $this;
+    }
 }

tests/FluidTableTest.php

@@ -116,6 +116,27 @@ public function testTimestamps()
         }
     }
 
+    public function testInherits()
+    {
+        $schema = new Schema();
+        $fluid = new FluidSchema($schema);
+
+        $contacts = $fluid->table('contacts');
+        $contacts->id();
+
+        $fluid->table('users')->extends('contacts');
+
+        $dbalColumn = $schema->getTable('users')->getColumn('id');
+
+        $this->assertSame(Type::getType(Type::INTEGER), $dbalColumn->getType());
+        $fks = $schema->getTable('users')->getForeignKeys();
+        $this->assertCount(1, $fks);
+        $fk = array_pop($fks);
+        $this->assertSame('users', $fk->getLocalTableName());
+        $this->assertSame('contacts', $fk->getForeignTableName());
+        $this->assertSame(['id'], $fk->getLocalColumns());
+    }
+
     public function testGetDbalSchema()
     {
         $schema = new Schema();