Table of Contents
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Setting up Mutations
A mutation is something that “mutates” or changes the data in the server. In DB terms, if we need to change the data in a table using graphql we need mutations — be it an INSERT, UPDATE or DELETE. Only SELECTs are covered with a Query.
So to add a new speaker to the database we need a mutation.
In the GraphQL language, a mutation is of the form
mutation AddSpeaker($name:String, $talkTitle:String) {
createSpeaker(name: $name, talkTitle:$talkTitle) {
success
errors
}
}
A set of “query” variables needs to be supplied to the GraphQL endpoint. Say for example,
{
"name": "John Doe",
"talkTitle": "Introduction to GraphQL in Ruby"
}
Read more about GraphQL mutations and its syntax in the specifications — https://graphql.org/learn/queries/#mutations.
For our little server to accept mutations, we need to make some changes and add more files for defining mutations. Lets see how, step-by-step.
Adding a Mutation root type
A mutation root MutationType has to be created and it should then be added to our Schema, like the QueryType that was added in the last post.
| require 'graphql' | |
| require_relative 'mutations/create_speaker' | |
| class MutationType < GraphQL::Schema::Object | |
| description "The mutation root of this schema" | |
| field :createSpeaker, mutation: Mutations::CreateSpeaker | |
| end |
| require 'graphql' | |
| require_relative 'query' | |
| require_relative 'mutation' | |
| class ConferenceAppSchema < GraphQL::Schema | |
| query QueryType | |
| mutation MutationType | |
| end |