Ajax从Rails控制器获取数据

Question

I am trying to use ajax to get information from my controller. Basically I want to know if a data already exists in the DB or not, so my controller will return either true or false. At the moment I am just trying to set the basic ajax call

in my js file I have the following ajax call, as you can see at the moment I am not really doing any logic because my data is just a placeholder. Later I will add the information I want to query

$.ajax({
  type: "GET",
  url: "/locations/exists",
  dataType: "JSON",
  data: { 'locition_exist': loc_exit },
  success: function(data) {
    console.log(data);
  }
});

In my controller I have

  def exists
    location_exists = true
    respond_to do |format|
      format.html
      format.json {render json: location_exists }
    end
  end

Later value will go into a method in the model that will query the DB and return true/false.

In my routes I have

  resources :locations 
  get 'locations/exists', to: 'locations#exists'

This code results in the following error

The action 'show' could not be found for LocationsController

I am new to rails and ajax , and I based my code on different examples that I read here, so I am probably just doing a stupid noob mistake. Thank you very much for your help

Answer 1

When using get or match in routes, you need to define the controller method mapped

get 'locations/value', to: 'locations#value'

update

You saw the same error after updating routes. There are two reasons of this error:

1. You defined resources :location at first. The url locations/exists itself matches "show" method within resources, with Routes taking 'exists' as the id in #show .

2. You have not defined show within LocationsController

So, Routes will firstly map the url to locations#show with the :id as 'exists' , then hits the controller and found #show does not exist.

The solution after your updating

Of course you can put get 'exists'... before resources but that looks ugly.

Since 'exists' requires no id, it is a collection method. So you can use Routes built-in ways to do that.

resources :locations do
  collection do
    get 'exists'
  end
end 

By this all your resources and 'exists' can live.