Make params required in a rails api - ruby-on-rails

Question

I have a controller that accepts three params, title, users and project_type. I want to make all the params required
I have seen people do things like
def project_params
params.require(:title,:project_type, :users)
.permit(:title, :project_type, :users)
end
And then do Project.new(project_params), but I need to work a little with the params first. How can I make this possible?
I make a post request in postman like this:
module Api
module V1
class ProjectsController < ApplicationController
def create
admins = params[:admins]
users = get_user_array()
project_type = ProjectCategory.find_by(name: params[:project_type])
project = Project.new(
title: params[:title],
project_category: project_type,
project_users: users)
if project.save
render json: {data:project}, status: :ok
else
render json: {data:project.errors}, status: :unprocessable_entity
end
end
...
end
end
end
{
"title": "Tennis",
"project_type": "Sports",
"users": [{"name": "john Dow", "email": "johnDoe#gmail.com"}],
}

Answer 1

I would say that you are using ActionController::Parameters#require wrong. Its not meant to validate that the all the required attributes are present - thats what model validations are for. Rather you should just use params.require to ensure that the general structure of the parameters is processable.
For example if you used the rails scaffold you would get the following whitelist:
params.require(:project)
.permit(:title, :project_type)
This is because there is no point in continuing execution if the project key is missing from the params hash since this would give you an empty hash or nil.
ActionController::Parameters#require will raise a ActionController::ParameterMissing error which will return a 400 - Bad Request response which is the wrong response code for what you are doing. You also should not use exceptions for normal application flow. A missing attribute is not an exceptional event.
Instead if you want to use a flat params hash you should whitelist it with:
def project_params
params.permit(:title, :project_type, users: [:name, :email])
end

Answer 2

I think that if you don't have to get anything from the frontend to run get_user_array(), you could only allow and require title and project_type.
def create
users = get_user_array()
project = Project.new(project_params)
project.users = users
if project.save
render json: {data:project}, status: :ok
else
render json: {data:project.errors}, status: :unprocessable_entity
end
end
private
def project_params
params.require(:project).permit(:title, :project_type).tap do |project_params|
project_params.require(:title, :project_type)
end
end
If you need to process something before creating the project, you can do this:
project_category = ProjectCategory.find_by(name: project.project_type)