Map database column types to PHPStan types

Author: paulbalandan

src/Database/Schema/ColumnTypeResolver.php

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+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) 2023 CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\PHPStan\Database\Schema;
+
+use PHPStan\Type\FloatType;
+use PHPStan\Type\IntegerType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+
+/**
+ * Maps an introspected column to the PHPStan type of its raw, uncast database value.
+ */
+final class ColumnTypeResolver
+{
+    public function resolve(Column $column): Type
+    {
+        $type = $this->mapDeclaredType($column->type);
+
+        return $column->nullable ? TypeCombinator::addNull($type) : $type;
+    }
+
+    private function mapDeclaredType(string $declaredType): Type
+    {
+        $declaredType = strtoupper($declaredType);
+
+        // Checks follow SQLite's column affinity precedence.
+        // https://www.sqlite.org/datatype3.html#determination_of_column_affinity
+        if (str_contains($declaredType, 'INT')) {
+            return new IntegerType();
+        }
+
+        if (
+            str_contains($declaredType, 'CHAR')
+            || str_contains($declaredType, 'CLOB')
+            || str_contains($declaredType, 'TEXT')
+            || str_contains($declaredType, 'BLOB')
+            || $declaredType === ''
+        ) {
+            return new StringType();
+        }
+
+        if (
+            str_contains($declaredType, 'REAL')
+            || str_contains($declaredType, 'FLOA')
+            || str_contains($declaredType, 'DOUB')
+        ) {
+            return new FloatType();
+        }
+
+        // NUMERIC affinity (DECIMAL, NUMERIC, DATE, DATETIME, ...), read back as strings without a cast.
+        return new StringType();
+    }
+}

tests/Database/Schema/ColumnTypeResolverTest.php

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+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) 2023 CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\PHPStan\Tests\Database\Schema;
+
+use CodeIgniter\PHPStan\Database\Schema\Column;
+use CodeIgniter\PHPStan\Database\Schema\ColumnTypeResolver;
+use PHPStan\Type\VerbosityLevel;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @internal
+ */
+#[Group('unit')]
+final class ColumnTypeResolverTest extends TestCase
+{
+    #[DataProvider('provideMapsDeclaredTypeToPhpStanTypeCases')]
+    public function testMapsDeclaredTypeToPhpStanType(string $declaredType, bool $nullable, string $expected): void
+    {
+        $type = (new ColumnTypeResolver())->resolve(new Column('column', $declaredType, $nullable, false, null));
+
+        self::assertSame($expected, $type->describe(VerbosityLevel::precise()));
+    }
+
+    /**
+     * @return iterable<string, array{string, bool, string}>
+     */
+    public static function provideMapsDeclaredTypeToPhpStanTypeCases(): iterable
+    {
+        yield 'INTEGER' => ['INTEGER', false, 'int'];
+
+        yield 'INT' => ['INT', false, 'int'];
+
+        yield 'BIGINT' => ['BIGINT', false, 'int'];
+
+        yield 'VARCHAR' => ['VARCHAR', false, 'string'];
+
+        yield 'TEXT' => ['TEXT', false, 'string'];
+
+        yield 'BLOB' => ['BLOB', false, 'string'];
+
+        yield 'REAL' => ['REAL', false, 'float'];
+
+        yield 'FLOAT' => ['FLOAT', false, 'float'];
+
+        yield 'DOUBLE' => ['DOUBLE', false, 'float'];
+
+        yield 'DATETIME (numeric -> string)' => ['DATETIME', false, 'string'];
+
+        yield 'DECIMAL (numeric -> string)' => ['DECIMAL', false, 'string'];
+
+        yield 'nullable INTEGER' => ['INTEGER', true, 'int|null'];
+
+        yield 'nullable VARCHAR' => ['VARCHAR', true, 'string|null'];
+    }
+}