03-fragments.md

Fragments

A fragments is a group of fields that can be reused.

1. Execute this query:

   {
       first: organization(login: "facebook") {
           login
           id
           url
           membersWithRole {
             totalCount
           }
       }
       second: organization(login: "Netflix") {
           id
           url
           membersWithRole {
             totalCount
           }
       }
   }
   

   Note: Auto-complete doesn't work when using aliases in GraphiQL (bug?). Remove the alias temporarily to see the correct autocompletions.

2. This can be rewritten, as there is duplication across the subfields. First, define a fragment that contains the fields you want to reuse, but don't execute the query yet:

   fragment orgFields on Organization {
     login
     location
     websiteUrl
     membersWithRole {
       totalCount
     }
   }
   

You can choose the fragment name (I've chosen orgFields). Fragments must specify the type they apply to. This is what the on clause does, and enables the fragment fields to be type checked.

Now apply this fragment by using the spread operator (...) before the fragment name. Type the following query either before or after your fragment definition, and execute it:

{
  first: organization(login: "facebook") {
    login
    ...orgFields
  }
  second: organization(login: "Netflix") {
    ...orgFields
  }
}

3. Now your turn. Retrieve the Users with logins "stubailo" and "gaearon", and the fields login,name,createdAt, company, location and email. Use fragments to reuse the common fields.

4. Notice that you can mix fields and fragments as we did in the first query above (...orgFields and country). What happens if you specify a field twice - in both the fragment and the query that uses it?

5. Can fragments contain nested fields?