how to permit an array with strong parameters

📝How to Permit an Array with Strong Parameters

Are you having trouble saving ids from an associated model in your Rails 4 app while it worked seamlessly in the Rails 3 version? You might be facing an issue with strong parameters. Don't worry, we've got you covered! In this blog post, we'll explore the problem, provide easy solutions, and modify your code to fix the issue.

First, let's understand the problem. In your Rails 4 app, when you try to save a new question with category ids passed as parameters, you encounter the following error in the server logs:

Unpermitted parameters: category_ids

This error indicates that the category_ids parameter is not permitted in your controller's code. Let's dive into the solutions to resolve this issue.

✨Solution: Permitting the Array

To permit the category_ids array, you need to modify your questions_controller.rb by adding the category_ids attribute to the list of permitted parameters. Here's an example of how your question_params method should look:

def question_params
  params.require(:question).permit(:question_details, :question_content, :user_id, :accepted_answer_id, :province_id, :city, category_ids: [])
end

By specifying category_ids: [], you permit the category_ids array, allowing it to be saved along with the question.

🚀Example: Create Action Comparison

Let's compare the create actions from both your Rails 3 and Rails 4 apps to demonstrate the code changes.

Here's the create action from the Rails 3 app:

def create
  @question = Question.new(params[:question])
  respond_to do |format|
    if @question.save
      format.html { redirect_to @question, notice: 'Question was successfully created.' }
      format.json { render json: @question, status: :created, location: @question }
    else
      format.html { render action: "new" }
      format.json { render json: @question.errors, status: :unprocessable_entity }
    end
  end
end

And here's the create action from the Rails 4 app:

def create
  @question = Question.new(question_params)
  respond_to do |format|
    if @question.save
      format.html { redirect_to @question, notice: 'Question was successfully created.' }
      format.json { render json: @question, status: :created, location: @question }
    else
      format.html { render action: "new" }
      format.json { render json: @question.errors, status: :unprocessable_entity }
    end
  end
end

As you can see, the only difference is the usage of the question_params method in the Rails 4 version. This is where the permitted parameters, including category_ids, are handled.

📚Further Information

If you want to understand the concept of strong parameters in more detail, visit the official Rails documentation here.

That's it! Now you should be able to save the category_ids in your Rails 4 app without any issues. Go ahead and try it out! If you have any questions or face any difficulties, feel free to leave a comment below. Happy coding! 😊

💬Leave a Comment

Have you experienced any issues with strong parameters in Rails before? How did you solve them? Share your thoughts and experiences in the comments section. Let's learn and grow together!