Actions¶

Type¶

Actions can be of two types:

• Query action: An action of type query extends the query root of the Hasura schema. This means that you can execute this action through a GraphQL query. Query actions must be used where you want to fetch data from a data source without changing anything on the data source.
• Mutation action: An action of type mutation extends the mutation root of the Hasura schema. This means that you can execute this action through a GraphQL mutation. Mutation actions must be used when you want to mutate the state of a data source and fetch some data.

Definition¶

The action definition consists of the following:

• Action Name: The action will be available as a query or mutation in the GraphQL schema named as the action name
• Arguments: Arguments are used to pass dynamic values along with the query/mutation.
• Response type: The GraphQL type of the response that the query or mutation will return. Actions can only return object types.

For instance, consider this action definition:

extend type Mutation {
  userLogin(username: String!, password: String!): UserInfo
}

In this definition, we are extending the mutation root with an action called userLogin.

• userLogin is the action name
• username and password are the arguments that accept non-nullable string values.
• UserInfo is the response type of the action

Custom Types

An action must return an object type. This means, you will have to define your custom types like so:

type UserInfo {
  accessToken: String!
  userId: Int!
}

Read more about custom types.

Handler¶

Once you define the action types, you also have to specify the logic to run when the action is executed. This can be done in an HTTP webhook, also called the action handler. It could be a REST endpoint or a serverless function.

Learn more about writing an action handler.

Kind¶

Mutation actions are of two kinds:

• Synchronous: Sync actions return a response to the client after receiving a response from the handler.
• Asynchronous: Async actions return an action id as response to the client before receiving a response from the handler and allow the client to subscribe to the actual response using the action id.

Query actions don’t have a kind, they always behave like sync mutation actions.