@grafoo/bindings

Grafoo Bindings for Frameworks

This packages purpose is to standardize how view layer integrations are implemented for Grafoo. @grafoo/bindings has only a default export that is a createBindings factory function that returns an interface that provides data and notify for changes.

API

Arguments

Argument	type	Description
client	GrafooClient	a client nstance
props	object	a props object passed by the user (description below)
updater	function	a callback to notify for data changes

Example

import createBindings from "@grafoo/bindings";
import createClient from "@grafoo/core";

function fetchQuery(query, variables) {
  const init = {
    method: "POST",
    body: JSON.stringify({ query, variables }),
    headers: {
      "content-type": "application/json"
    }
  };

  return fetch("http://some.graphql.api", init).then(res => res.json());
}

const client = createClient(fetchQuery);
const props = {};
const updater = () => {};

const bindings = createBindings(client, props, updater);

props argument

Name	type	Descrition
query	object	the query created with @grafoo/core/tag's template tag
variables	object	GraphQL variables object for the query
mutations	object	an object where mutations are declared (description below)
skip	boolean	whether the client should skip the query request

Mutations

The mutations prop is a map of mutation objects that are shaped like so:

const createPost = {
  query: CREATE_POST_MUTATION,
  optimisticUpdate: ({ allPosts }, variables) => ({
    allPosts: [{ ...variables.postInput, id: "tempID" }, ...allPosts]
  }),
  update: ({ allPosts }, response) => ({
    allPosts: allPosts.map(p => (p.id === "tempID" ? response.post : p))
  })
};

const mutations = { createPost };

A mutation object receives the following props:

Name	Type	Required	Descrition
query	object	true	a mutation query created with @grafoo/core/tag
update	function	false	updates the cache when a request is completed (description below)
optimisticUpdate	function	false	updates the cache before a request is completed (description below)

Each mutation will generate a single function that accepts a GraphQL variables object as argument and return a promise that will resolve with the mutation data or reject with GraphQL errors.

type MutationFn = (variables: Variables) => Promise<MutationData>;

Mutation query dependency

Important to notice that to update the cache update and optimistUpdate hooks depend on a query and it's variables object props (they need to be passed in the props object argument). If you need to perform a mutation but updating the cache is not strictly important you can just use the mutation promise resolved data or use the client instance directly.

update

type UpdateFn = (query: QueryData, data: MutationData) => CacheUpdate;

The mutation update function is resposible to update the cache when the request is completed. It receives as paremeters an object containing the data from the query it depends upon and the mutation result. update return type is an object that describes the changes to be made to the cache.

optimisticUpdate

type OptimistcUpdateFn = (query: QueryData, variables: Variables) => CacheUpdate;

In modern UIs it's to be expected that every user interaction occur in a fraction of seconds. optimisticUpdate responsability is to skip the mutation network roundtrip and update the cache instantaneously, making sure such interactions are as fast as they can be. optimisticUpdate as in update takes as first paremater the depedent query data. As second paremater it receives the variables object with which it's correpondent generated mutation function was called. And again it should return an object that describes the changes to be made to cache.

If you want to perform an optimitic update you have to make sure that the data you are inserting contains the field or fields to extract a unique identifier. For instance, say @grafoo/babel-plugin idFields option is set to insert a property id. Is to be expected that your update has that field mocked.

Bindings

The object returned by createBindings contains the following props.

Name	type	Descrition
client	object	the client instance
load	function	a method to execute a query with the query prop
loading	boolean	whether the client is executing a query or not
loaded	boolean	whether the query data is already cached
errors	string[]	an array of GraphQL errors from a failed request to your API

The remaining props are:

• the data fetched by the client and shaped according to your query
• mutation functions generated by the mutations object prop

LICENSE

MIT