How to validate the inputs from user in Laravel - php

Question

I want to invalidate some inputs.I write these code in store method,but when I test my api on Postman give me 500 error.For example I don't give bodyfield in Body tab.
This is store function in my controller.
public function store(Request $request)
{
$validation=$this->getValidationFactory()->make($request->all(),[
'body'=>'required',
'image'=>'required|mimes:jpeg,png'
]);
if($validation->failed()){
return response()->json(['message'=>'Invalid Input Data!'],400);
}
$article=new Article();
$article->title=$request->title;
$article->body=$request->body;
$article->source=$request->source;
if($article->save()){
$article->categories()->sync($request->categories);
}
$name='article-'.$article->id.'.'.$request->file('image')->getClientOriginalExtension();
$request->file('image')->move(public_path('images'),$name);
$article->image= $name;
$article->save();
return response()->json(['message'=>'save successfully'],200);
}
This is migration file for create article table.
public function up()
{
Schema::create('articles', function (Blueprint $table) {
$table->increments('id');
$table->string('title')->nullable();
$table->text('body');
$table->boolean('is_active')->default(0);
$table->enum('status',['draft','completed','published'])->default('draft');
$table->timestamps();
});
}
And this is Postman screenshot.