From 39fca5a9acb20395aca6534f09bdc02f792be291 Mon Sep 17 00:00:00 2001
From: Tim MacDonald <hello@timacdonald.me>
Date: Fri, 30 Dec 2022 12:29:22 +1100
Subject: [PATCH] [9.x] Fix decimal cast precision issue (#45456)

* add failing test for decimal precision

* fix decimal cast precision with manual string manipulation
---
 .../Eloquent/Concerns/HasAttributes.php       | 11 +++-
 .../EloquentModelDecimalCastingTest.php       | 62 +++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php b/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
index 4b787352cfc8..e0e532e6fdba 100644
--- a/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
+++ b/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
@@ -31,6 +31,7 @@
 use ReflectionClass;
 use ReflectionMethod;
 use ReflectionNamedType;
+use TypeError;
 
 trait HasAttributes
 {
@@ -1318,7 +1319,15 @@ public function fromFloat($value)
      */
     protected function asDecimal($value, $decimals)
     {
-        return number_format($value, $decimals, '.', '');
+        $value = (string) $value;
+
+        if (! is_numeric($value)) {
+            throw new TypeError('$value must be numeric.');
+        }
+
+        [$int, $fraction] = explode('.', $value) + [1 => ''];
+
+        return $int.'.'.Str::of($fraction)->limit($decimals, '')->padLeft($decimals, '0');
     }
 
     /**
diff --git a/tests/Integration/Database/EloquentModelDecimalCastingTest.php b/tests/Integration/Database/EloquentModelDecimalCastingTest.php
index fb7e35d49001..33e9c5ded67f 100644
--- a/tests/Integration/Database/EloquentModelDecimalCastingTest.php
+++ b/tests/Integration/Database/EloquentModelDecimalCastingTest.php
@@ -6,6 +6,7 @@
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Support\Facades\Schema;
 use Illuminate\Tests\Integration\Database\DatabaseTestCase;
+use TypeError;
 
 class EloquentModelDecimalCastingTest extends DatabaseTestCase
 {
@@ -18,6 +19,67 @@ protected function defineDatabaseMigrationsAfterDatabaseRefreshed()
         });
     }
 
+    public function testItThrowsOnNonNumericValues()
+    {
+        $model = new class extends Model {
+            public $timestamps = false;
+
+            protected $casts = [
+                'amount' => 'decimal:20',
+            ];
+        };
+        $model->amount = 'foo';
+
+        $this->expectException(TypeError::class);
+
+        $model->amount;
+    }
+
+    public function testItHandlesLargeNumbers()
+    {
+        $model = new class extends Model {
+            public $timestamps = false;
+
+            protected $casts = [
+                'amount' => 'decimal:20',
+            ];
+        };
+
+        $model->amount = '0.89898989898989898989';
+        $this->assertSame('0.89898989898989898989', $model->amount);
+
+        $model->amount = '89898989898989898989';
+        $this->assertSame('89898989898989898989.00000000000000000000', $model->amount);
+    }
+
+    public function testItTrimsLongValues()
+    {
+        $model = new class extends Model {
+            public $timestamps = false;
+
+            protected $casts = [
+                'amount' => 'decimal:20',
+            ];
+        };
+
+        $model->amount = '0.89898989898989898989898989898989898989898989';
+        $this->assertSame('0.89898989898989898989', $model->amount);
+    }
+
+    public function testItDoesntRoundNumbers()
+    {
+        $model = new class extends Model {
+            public $timestamps = false;
+
+            protected $casts = [
+                'amount' => 'decimal:1',
+            ];
+        };
+
+        $model->amount = '0.99';
+        $this->assertSame('0.9', $model->amount);
+    }
+
     public function testDecimalsAreCastable()
     {
         $user = TestModel1::create([