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Operations

Operations are functions available within an Mutate Transaction callback with access to internal context including the current mutable version of the DocumentStore being operated on.

Base Operations​

The ones that are provided by GraphQL Paper out-of-the-box are create, find, remove, clone, getStore, queueEvent. These are covered in Mutating Data.

Operational Context​

What makes Operations different than regular functions is that the first argument is bound (via .bind) at the beginning of every transaction, for each operation, with Operation Context.

The shape of the Operation Context is:

{
  store: DocumentStore
  schema: GraphQLSchema
  eventQueue: Event[]
}
  • store is the current mutable version of the store available during the transaction
  • schema is an instance of GraphQLSchema based on the schema passed into Paper
  • eventQueue is an array of events that will be emitted at the end of the transaction

Creating Custom Operations​

Additional Operations can be added to be used within the Mutate Transaction callback. The first argument is reserved and must be the context object even if it's not used for the custom operation. What is provided by the OperationContext argument is described above.

export const customOperation = (context, argOne, argTwo) => {
  /* custom logic for your custom operation */
};

If using typescript, import the OperationContext for the first argument of the function. Setting up your Operation this way should allow the types and autocomplete to work within the the Mutate Transaction callback.

// customOperation.ts
import { OperationContext }  from 'graphql-paper/types';

export const customOperation = (context: OperationContext, argOne: string, argTwo: number) => {
  /* custom logic for your custom operation */
  return /* return anything useful as a result of the operation */;
};

Operations can be added to the Paper constructor's second argument configuration object, on the operations key.

import { customOperation } from './customOperation';
import { graphqlSchema } from './schema';

const operations = { custom: customOperation };
const paper = new Paper(graphqlSchema, { operations });
import { customOperation } from './customOperation';
import { graphqlSchema } from './schema';

const operations = { custom: customOperation };
const paper = new Paper(graphqlSchema, { operations });

The key provided in the OperationMap hash is what is made available by destructuring within the Mutate Transaction callback.

paper.mutate(({ custom }) => {
  const result = custom('argOne magic!', 42);
});