How to indicate empty array in HTTP request query params?

Question

This is the way Rails accepts arrays in query parameters:

PUT /resource.json?sport_ids[]=133&sport_ids[]=64&sport_ids[]=71 ...

I tried to google this question but didn't find any explicit docs on it:

How to tell Rails that we want sport_ids to become empty (pass empty array of sport_ids via query parameters) ?

Answer 1

• HTTP requests can have only variables on the url itself. That's a limitation feature of HTTP, not Rails.

• Take a look at How Does Rack Parse Query Params? With Parse_nested_query to figure out how rails collects the variables into an array, it won't run out of the box in case of an empty array.

You can avoiding sending the params["sport_ids"] and patch your controller with:

params["sport_ids"] ||= []

---

The best practice to use put/post requests, is passing such data in the request body (json/xml) like:

  {
    "sport_ids": []
  }

Or with data as:

//...
  {
    "sport_ids": [133, 64, 71]
  }
//...

---

For more info about HTTP request steps, check Running a HTTP request with rails.