Live Queries#

GraphQL Live Query implementation from Laurin Quast can be used in GraphQL Mesh with a few additions in the configuration.

Basic Usage#

You have a Query root field that returns all Todo entities from your data source like below.

query getTodos {
 todos {
 id
 content
 }
}

And you want to update this operation result automatically without manual refresh when Mutation.addTodo is called.

You only need to add the following to your existing configuration.

additionalTypeDefs: |
 directive @live on QUERY
liveQueryInvalidations:
 - field: Mutation.addTodo
 invalidate:
 - Query.todos

Then you can send a live query with @live directive.

query getTodos @live {
 todos {
 id
 content
 }
}

This will start a real-time connection between the server and your client. The response of todos will get updated whenever addTodo is called.

ID Based Invalidation#

Let's say you have the following query that returns a specific Todo entity based on id field;

query getTodo($id: ID!) {
 todo(id: $id) {
 id
 content
 }
}

If you update this entity with editTodo mutation field on your backend, then you want to invalidate this entity specifically instead of validating all todo queries;

liveQueryInvalidations:
 - field: Mutation.editTodo
 invalidate:
 - Todo:{args.id}

In a case where the field resolver resolves null but might resolve to an object type later, e.g., because the visibility got update the field that uses a specific id argument can be invalidated in the following way:

liveQueryInvalidations:
 - field: Mutation.editTodo
 invalidate:
 - Query.todo(id:"{args.id}")

Programmatic Usage#

liveQueryStore is available in GraphQL Context, so you can access it in resolvers composition functions that wrap existing resolvers or additional resolvers;

See Resolvers Composition

transforms:
 - resolversComposition:
 - resolver: Mutation.editTodo
 composer: invalidate-todo#invalidateTodo

And in this code file;

module.exports = {
 invalidateTodo: next => async (root, args, context, info) => {
 const result = await next(root, args, context, info);
 context.liveQueryStore.invalidate(`Todo:${args.id}`);
 return result;
 }
}

You can learn more about GraphQL Live Query in its documentation.

You can check out our example that uses live queries