Fix composite primary key reflection in postgres.

Reflecting composite keys that use serial columns should behave
correctly, marking the serial column as autoIncrement.

src/Database/Schema/PostgresSchema.php

@@ -139,6 +139,10 @@ class PostgresSchema extends BaseSchema
                 $row['default'] = 0;
             }
         }
+        // Sniff out serial types.
+        if (in_array($field['type'], ['integer', 'biginteger']) && strpos($row['default'], 'nextval(') === 0) {
+            $field['autoIncrement'] = true;
+        }
         $field += [
             'default' => $this->_defaultValue($row['default']),
             'null' => $row['null'] === 'YES' ? true : false,
@@ -231,9 +235,10 @@ class PostgresSchema extends BaseSchema
             // If there is only one column in the primary key and it is integery,
             // make it autoincrement.
             $columnDef = $table->column($columns[0]);
-            if (count($columns) === 1 &&
-                in_array($columnDef['type'], ['integer', 'biginteger']) &&
-                $type === Table::CONSTRAINT_PRIMARY
+            if (
+                $type === Table::CONSTRAINT_PRIMARY &&
+                count($columns) === 1 &&
+                in_array($columnDef['type'], ['integer', 'biginteger'])
             ) {
                 $columnDef['autoIncrement'] = true;
                 $table->addColumn($columns[0], $columnDef);

tests/TestCase/Database/Schema/PostgresSchemaTest.php

@@ -346,6 +346,34 @@ SQL;
     }
 
     /**
+     * Test describing a table with postgres and composite keys
+     *
+     * @return void
+     */
+    public function testDescribeTableCompositeKey()
+    {
+        $this->_needsConnection();
+        $connection = ConnectionManager::get('test');
+        $sql = <<<SQL
+CREATE TABLE schema_composite (
+    "id" SERIAL,
+    "site_id" INTEGER NOT NULL,
+    "name" VARCHAR(255),
+    PRIMARY KEY("id", "site_id")
+);
+SQL;
+        $connection->execute($sql);
+        $schema = new SchemaCollection($connection);
+        $result = $schema->describe('schema_composite');
+        $connection->execute('DROP TABLE schema_composite');
+
+        $this->assertEquals(['id', 'site_id'], $result->primaryKey());
+        $this->assertNull($result->column('site_id')['autoIncrement'], 'site_id should not be autoincrement');
+        $this->assertTrue($result->column('id')['autoIncrement'], 'id should be autoincrement');
+    }
+
+
+    /**
      * Test describing a table containing defaults with Postgres
      *
      * @return void

tests/TestCase/ORM/TableTest.php

@@ -2004,10 +2004,10 @@ class TableTest extends TestCase
     public function testSaveNewCompositeKeyIncrement()
     {
         $articles = TableRegistry::get('SiteAuthors');
-        $article = $articles->newEntity(['site_id' => 1, 'name' => 'new guy']);
+        $article = $articles->newEntity(['site_id' => 3, 'name' => 'new guy']);
         $this->assertSame($article, $articles->save($article));
         $this->assertNotEmpty($article->id, 'Primary key should have been populated');
-        $this->assertSame(1, $article->site_id);
+        $this->assertSame(3, $article->site_id);
     }
 
     /**