[9.x] Allow model accessors to cache any value (#41673)

* allow caching any value with an accessor

* fix accessors caching null values

* use shouldCache

Co-authored-by: Taylor Otwell <[email protected]>

Author: SjorsO

src/Illuminate/Database/Eloquent/Casts/Attribute.php

@@ -18,6 +18,13 @@ class Attribute
      */
     public $set;
 
+    /**
+     * Indicates if caching is enabled for this attribute.
+     *
+     * @var bool
+     */
+    public $withCaching = false;
+
     /**
      * Indicates if caching of objects is enabled for this attribute.
      *
@@ -83,4 +90,16 @@ public function withoutObjectCaching()
 
         return $this;
     }
+
+    /**
+     * Enable caching for the attribute.
+     *
+     * @return static
+     */
+    public function shouldCache()
+    {
+        $this->withCaching = true;
+
+        return $this;
+    }
 }

src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

@@ -630,7 +630,7 @@ protected function mutateAttribute($key, $value)
      */
     protected function mutateAttributeMarkedAttribute($key, $value)
     {
-        if (isset($this->attributeCastCache[$key])) {
+        if (array_key_exists($key, $this->attributeCastCache)) {
             return $this->attributeCastCache[$key];
         }
 
@@ -640,10 +640,10 @@ protected function mutateAttributeMarkedAttribute($key, $value)
             return $value;
         }, $value, $this->attributes);
 
-        if (! is_object($value) || ! $attribute->withObjectCaching) {
-            unset($this->attributeCastCache[$key]);
-        } else {
+        if ($attribute->withCaching || (is_object($value) && $attribute->withObjectCaching)) {
             $this->attributeCastCache[$key] = $value;
+        } else {
+            unset($this->attributeCastCache[$key]);
         }
 
         return $value;
@@ -1023,10 +1023,10 @@ protected function setAttributeMarkedMutatedAttributeValue($key, $value)
             )
         );
 
-        if (! is_object($value) || ! $attribute->withObjectCaching) {
-            unset($this->attributeCastCache[$key]);
-        } else {
+        if ($attribute->withCaching || (is_object($value) && $attribute->withObjectCaching)) {
             $this->attributeCastCache[$key] = $value;
+        } else {
+            unset($this->attributeCastCache[$key]);
         }
     }
 

tests/Integration/Database/DatabaseEloquentModelAttributeCastingTest.php

@@ -202,6 +202,70 @@ public function testCastsThatOnlyHaveGetterThatReturnsPrimitivesAreNotCached()
         }
     }
 
+    public function testAttributesCanCacheStrings()
+    {
+        $model = new TestEloquentModelWithAttributeCast;
+
+        $previous = $model->virtual_string_cached;
+
+        $this->assertIsString($previous);
+
+        $this->assertSame($previous, $model->virtual_string_cached);
+    }
+
+    public function testAttributesCanCacheBooleans()
+    {
+        $model = new TestEloquentModelWithAttributeCast;
+
+        $first = $model->virtual_boolean_cached;
+
+        $this->assertIsBool($first);
+
+        foreach (range(0, 10) as $ignored) {
+            $this->assertSame($first, $model->virtual_boolean_cached);
+        }
+    }
+
+    public function testAttributesCanCacheNull()
+    {
+        $model = new TestEloquentModelWithAttributeCast;
+
+        $this->assertSame(0, $model->virtualNullCalls);
+
+        $first = $model->virtual_null_cached;
+
+        $this->assertNull($first);
+
+        $this->assertSame(1, $model->virtualNullCalls);
+
+        foreach (range(0, 10) as $ignored) {
+            $this->assertSame($first, $model->virtual_null_cached);
+        }
+
+        $this->assertSame(1, $model->virtualNullCalls);
+    }
+
+    public function testAttributesByDefaultDontCacheBooleans()
+    {
+        $model = new TestEloquentModelWithAttributeCast;
+
+        $first = $model->virtual_boolean;
+
+        $this->assertIsBool($first);
+
+        foreach (range(0, 50) as $ignored) {
+            $current = $model->virtual_boolean;
+
+            $this->assertIsBool($current);
+
+            if ($first !== $current) {
+                return;
+            }
+        }
+
+        $this->fail('"virtual_boolean" seems to be cached.');
+    }
+
     public function testCastsThatOnlyHaveGetterThatReturnsObjectAreCached()
     {
         $model = new TestEloquentModelWithAttributeCast;
@@ -362,6 +426,38 @@ function () {
         );
     }
 
+    public function virtualStringCached(): Attribute
+    {
+        return Attribute::get(function () {
+            return Str::random(10);
+        })->shouldCache();
+    }
+
+    public function virtualBooleanCached(): Attribute
+    {
+        return Attribute::get(function () {
+            return (bool) mt_rand(0, 1);
+        })->shouldCache();
+    }
+
+    public function virtualBoolean(): Attribute
+    {
+        return Attribute::get(function () {
+            return (bool) mt_rand(0, 1);
+        });
+    }
+
+    public $virtualNullCalls = 0;
+
+    public function virtualNullCached(): Attribute
+    {
+        return Attribute::get(function () {
+            $this->virtualNullCalls++;
+
+            return null;
+        })->shouldCache();
+    }
+
     public function virtualObject(): Attribute
     {
         return new Attribute(