Laravel 5.1 How to use the same form request rules for two methods when a field is required in one but not in the other method?

public function rules()
{
    $rules = [
        'comment' => 'max:2000',
        'source' => 'different:target',
        'file1' => 'required_without_all:file2,file3|between:1,15360|mimes:txt,pdf',
        'file2' => 'required_without_all:file1,file3|between:1,15360|mimes:txt,pdf',
        'file3' => 'required_without_all:file1,file2|between:1,15360|mimes:txt,pdf',
    ];

    if ($this->entity_id)
    {
        $rules['file1'] = 'between:1,15360|mimes:txt,pdf';
        $rules['file2'] = 'between:1,15360|mimes:txt,pdf';
        $rules['file3'] = 'between:1,15360|mimes:txt,pdf';
    }

    return $rules;
}

Replace entity id by the name of the url parameter identifying the model you are updating. If it is a post, with post_id in the url, use $this->post_id.

@pmall Thank you for your answer. I replaced the entity_id with post_id but the required validation is taking place in the update form. The edit form is as follows:

  {!! Form::model($project, [
                                'route'=>['myprojects.update', $project->id],
                                'method' => 'put',
                                'files' => true,
                                'class'=>'form'
                                ]
          ) !!}
...
        <div class="form-group col-lg-4">
                {!! Form::label('file1', 'Select file 1', ['class' => 'control-label']) !!}
                {!! Form::file('file1',['id'=>'file1']) !!}
            </div>
            <div class="form-group col-lg-4">
                {!! Form::label('file2', 'Select file 2', ['class' => 'control-label']) !!}
                {!! Form::file('file2', ['id'=>'file2']) !!}
            </div>
            <div class="form-group col-lg-4">
                {!! Form::label('file3', 'Select file 3', ['class' => 'control-label']) !!}
                {!! Form::file('file3', ['id'=>'file3']) !!}
            </div>
        </div>
        <div class="form-group">
            {!! Form::submit('Edit', ['class' => 'btn btn-block btn-success']) !!}
        </div>
        {!! Form::close() !!}

I replaced the entity_id with post_id

You have to put the name of the parameter you set in the route definition. Here you want to retrieve the id of the project, if it is null it is the store action, if it is filled it is the update action, hence the if. So I guess it is id or project_id.

@pmall project_id and id are not working also.

@pmall I used the follwing trick and it worked but in the store method the required rule is not validated:

 if($input['_method']='PUT')
    {
        $rules['file1'] = 'between:1,15360|mimes:txt,pdf';
        $rules['file2'] = 'between:1,15360|mimes:txt,pdf';
        $rules['file3'] = 'between:1,15360|mimes:txt,pdf';
    }

    return $rules;

project_id and id are not working also.

What is your route ? Do you understand the mechanism here ?

I used the follwing trick and it worked but in the store method the required rule is not validated:

if ($input['_method'] == 'PUT') // It is double equal

@pmall I'm kind of newbie to Laravel. I'm using resourceful routing. My route information are these: myprojects/{myprojects}/edit | myprojects.edit | App\Http\Controllers\MyProjectsController@edit

I used if($this->method()=="PUT") and it worked perfectly. Can you explain how?!

So the id of the my myproject entity is $this->myproject. If it is null it is creating a myproject, if it has a value it is updating the corresponding myproject.

The method of an update form is put so your second method works too.

If you want to access the id of the entity in the update controller action, you use $request->myproject. So it is exactly the same here, except in the request class you use $this->myproject.

@pmall Thanks a lot. This works as expected.