参数未传递给控制器

Question

Im trying to pass a client_id parameter from one of my views to a different models controller, but it seems like the param isn't being passed since I get the error "undefined method `client_id=' for nil:NilClass" in the set_client method. What am I doing wrong? ANy help would be appreciated. Thanks

<%= link_to 'New assessment', new_assessment_path(:client_id => @client.id), class: "btn btn-xs btn-success" %>

This is my controller:

class AssessmentsController < ApplicationController
  before_action :set_assessment, only: [:show, :edit, :update, :destroy]
  before_action :set_client, only: [:new]

  def new
    @assessment = Assessment.new
  end



 def create
    @assessment = Assessment.new(assessment_params)
    respond_to do |format|
      if @assessment.save
        format.html { redirect_to @assessment, notice: 'Assessment was successfully created.' }
        format.json { render :show, status: :created, location: @assessment }
      else
        format.html { render :new }
        format.json { render json: @assessment.errors, status: :unprocessable_entity }
      end
    end
  end



  def set_client
    @assessment.client_id = params[:client_id]
  end

Routes:

Rails.application.routes.draw do

resources :trainers
resources :clients
resources :assessments
root 'pages#home'

Answer 1

Main Reason for the undefined error is You are passing client_id to new method but not to the create method. And What i understood from ur question is You want add a assessment to a client.

If this is your goal follow these steps

1.create association in respective models.

add the following line in Client.rb

has_many: :assesments

and add in Assement.rb

belongs_to: Client

2.Now change ur routes.rb.

resources clients do
  resources assements do
  end
end 

3.Now check ur routes by executing this cmd rake routes now your routes should be like this

/clients/:client_id/assements/new(.:format)

4.Now you dont need to pass the client id param manually.

Hope this will help you in solving ur problem.

cmt here if any..

Answer 2

Your error reads:

undefined method `client_id=' for nil:NilClass

That's coming from:

def set_client
  @assessment.client_id = params[:client_id]
end

Which is being called before your new action due to:

before_action :set_client, only: [:new]

At that point, @assessment is nil in set_client because you haven't yet assigned the variable. Thus the error.

It has nothing to do with params not passing.

My suggestion is, remove the before_action and change the new action to:

def new
  @assessment = Assessment.new(client_id: params[:client_id])
end

Answer 3

在set_client方法中执行Assessment.find_by(client_id: params[:client_id]) 。

Answer 4

You are trying to set the client_id in @assessment , and that variable is not defined when you are trying to set it.

before_action 's callback is executed, as the name says, before the action (AKA method).

You should remove the before_action and add the setter within your new method

def new
  @assessment = Assessment.new
  @assessment.client_id = params[:client_id]
end

Answer 5

• 1.Set client in before_action
• 2.no need to create @assesment in new method

Change as below

class AssessmentsController < ApplicationController
  before_action :set_assessment, only: [:show, :edit, :update, :destroy]
  before_action :set_client, only: [:new]

  def new
  end



 def create
    @assessment = Assessment.new(assessment_params)
    respond_to do |format|
      if @assessment.save
        format.html { redirect_to @assessment, notice: 'Assessment was successfully created.' }
        format.json { render :show, status: :created, location: @assessment }
      else
        format.html { render :new }
        format.json { render json: @assessment.errors, status: :unprocessable_entity }
      end
    end
  end



  def set_client
    @client_id = Client.find_by(params[:client_id])
  end
end