Type Model findColumn as a list of the column's values

Author: paulbalandan

src/Type/ModelFetchedReturnTypeHelper.php

@@ -67,6 +67,27 @@ public function getFetchedReturnType(ClassReflection $classReflection, ?MethodCa
         return new ObjectWithoutClassType();
     }
 
+    /**
+     * Resolves the type of a single column's value, as returned element-wise by `findColumn()`.
+     */
+    public function getColumnFieldType(ClassReflection $classReflection, string $columnName): ?Type
+    {
+        $tableName = $classReflection->getNativeReflection()->getDefaultProperties()['table'] ?? null;
+
+        $table = is_string($tableName) && $tableName !== '' ? $this->schemaProvider->get()->getTable($tableName) : null;
+
+        if ($table === null) {
+            return null;
+        }
+
+        return $this->fieldType(
+            $columnName,
+            $table->getColumn($columnName),
+            $this->readStringMap($classReflection, 'casts'),
+            $this->readStringMap($classReflection, 'castHandlers'),
+        );
+    }
+
     private function resolveReturnType(ClassReflection $classReflection, ?MethodCall $methodCall, Scope $scope): string
     {
         if ($methodCall !== null && $methodCall->hasAttribute(ModelReturnTypeTransformVisitor::RETURN_TYPE)) {

src/Type/ModelFindReturnTypeExtension.php

@@ -42,10 +42,10 @@ public function getClass(): string
 
     public function isMethodSupported(MethodReflection $methodReflection): bool
     {
-        return in_array($methodReflection->getName(), ['find', 'findAll', 'first'], true);
+        return in_array($methodReflection->getName(), ['find', 'findAll', 'first', 'findColumn'], true);
     }
 
-    public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): Type
+    public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): ?Type
     {
         $methodName = $methodReflection->getName();
 
@@ -57,11 +57,44 @@ public function getTypeFromMethodCall(MethodReflection $methodReflection, Method
             return $this->getTypeFromFindAll($methodCall, $scope);
         }
 
+        if ($methodName === 'findColumn') {
+            return $this->getTypeFromFindColumn($methodCall, $scope);
+        }
+
         $classReflection = $this->getClassReflection($methodCall, $scope);
 
         return TypeCombinator::addNull($this->modelFetchedReturnTypeHelper->getFetchedReturnType($classReflection, $methodCall, $scope));
     }
 
+    private function getTypeFromFindColumn(MethodCall $methodCall, Scope $scope): ?Type
+    {
+        $args = $methodCall->getArgs();
+
+        if (! isset($args[0])) {
+            return null;
+        }
+
+        $strings = $scope->getType($args[0]->value)->getConstantStrings();
+
+        if (count($strings) !== 1) {
+            return null;
+        }
+
+        $fieldType = $this->modelFetchedReturnTypeHelper->getColumnFieldType(
+            $this->getClassReflection($methodCall, $scope),
+            $strings[0]->getValue(),
+        );
+
+        if ($fieldType === null) {
+            return null;
+        }
+
+        return TypeCombinator::addNull(TypeCombinator::intersect(
+            new ArrayType(new IntegerType(), $fieldType),
+            new AccessoryArrayListType(),
+        ));
+    }
+
     private function getClassReflection(MethodCall $methodCall, Scope $scope): ClassReflection
     {
         $classTypes = $scope->getType($methodCall->var)->getObjectClassReflections();

tests/data/type-inference/model-return-types.php

@@ -48,6 +48,12 @@
 // A selected field is still cast by the model (output name `user_id` casts via the model handler).
 assertType('array{user_id: CodeIgniter\PHPStan\Tests\Fixtures\Entity\Money}|null', $posts->select('user_id')->first());
 
+// findColumn() returns a list of the single column's values.
+assertType('list<int>|null', $comments->findColumn('id'));
+assertType('list<string|null>|null', $comments->findColumn('body'));
+assertType('list<CodeIgniter\PHPStan\Tests\Fixtures\Entity\Money>|null', $posts->findColumn('user_id'));
+assertType('list<CodeIgniter\I18n\Time>|null', $posts->findColumn('title'));
+
 function selectDynamically(BlogCommentModel $model, string $columns): void
 {
     assertType('array<string, mixed>|null', $model->select($columns)->asArray()->first());