Iguazu is a simple Redux-powered Async Query engine. By using a Higher-Order Component, Iguazu transparently manages dispatching async requests and injecting into React props. Iguazu has an ecosystem of adapters for various querying + caching strategies: Iguazu RPC, Iguazu GraphQL and Iguazu REST.

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📖 Table of Contents

• Features
• Usage
• Upgrading
• Contributing

✨ Features

• Streamlines dispatching, load states, and injecting into React props
• Parallel and sequential async requests
• Server-side rendering ready

Motivation

react-redux works great for when you want to take data that already exists in state and inject it as props into a React component, but it doesn't help you at all with the flow of loading asynchronous data into state. If a react component relies on asynchronous data you typically have to do three things:

1. Define a load action responsible for fetching the asynchronous data, which should be triggered on mount and when the component receives new props that change what data should be loaded
2. Define a mapStateToProps function and use selectors to get the data out of state
3. Determine whether the state is actually loaded based on the props the selectors return

Iguazu seeks to simplify this flow into one step.

🤹‍ Usage

Installation

npm install --save iguazu

Base Concepts

Iguazu exports a Higher Order Component (HOC) connectAsync similar to React Redux's connect. Instead of taking a mapStateToProps function, it takes a loadDataAsProps function. It should return a map where each key is the name of a prop that will contain some asynchronous data and the value is the load function that will load that data if it is not already loaded. The load function must synchronously return an object with the keys data, status, error, and promise. The key data should be the data returned from the asynchronous call. The key status should be either loading to signal the asynchronous call is in flight or complete to signal it has returned. The key error should be a truthy value if there was an error while loading. The key promise should be the promise of the asynchronous call.

For each key defined in the loadDataAsProps function, the HOC will pass a prop to the wrapped component that contains the data. It will also pass two function props, isLoading and loadedWithErrors, which will tell you if any of the async props are still loading or loaded with errors respectively. If you are only interested in a subset of async props, you can pass an array of the props names as the first argument. There will also be a prop named loadErrors that maps the load error, if there is one, for each prop. You can use this if you want to more granularly dig into what failed.

Example:

/* actions.js */
import React from 'react';
import { connectAsync } from 'iguazu';

export function queryMyData(param) {
  return (dispatch, getState) => {
    const data = getState().path.to.myData[param];
    const status = data ? 'complete' : 'loading';
    const promise = data ? Promise.resolve : dispatch(fetchMyData(param));

    return { data, status, promise };
  };
}

export function queryMyOtherData(param) { /* Essentially the same as queryMyData */ }

/* MyContainer.jsx */
function MyContainer({
  isLoading,
  loadedWithErrors,
  myData,
  myOtherData,
}) {
  if (isLoading()) {
    return <div>Loading...</div>;
  }

  if (loadedWithErrors()) {
    return <div>Oh no! Something went wrong</div>;
  }

  return (
    <div>
      myData =
      {' '}
      {myData}
      myOtherData =
      {' '}
      {myOtherData}
    </div>
  );
}

function loadDataAsProps({ store, ownProps }) {
  const { dispatch, getState } = store;
  return {
    myData: () => dispatch(queryMyData(ownProps.someParam)),
    myOtherData: () => dispatch(queryMyOtherData(getState().someOtherParam)),
  };
}

export default connectAsync({ loadDataAsProps })(MyContainer);

You can see that by moving the logic responsible for selecting out the cached data and triggering a fetch if needed into the actions makes the components much simpler.

Advanced Concepts

SSR

The main benefits of server side rendering are improved perceived speed and SEO. With perceived speed, the general best practice is to get something in front of the user's eyes as fast as possible. Typically that means you shouldn't wait for any data before rendering to string. For SEO, it's more important that you render the full content, and if that content is dynamic, you'll need to wait on some data. Usually not every view is important for SEO, such as logged in views, so the best option is to only preload data you absolutely have to for SEO. For this reason, Iguazu makes SSR data preloading opt in. If you would like a component's data to be loaded prior to rendering on the server, you can add a property named ssr with the value of true.

Example:

/* server.js */
import express from 'express';

const app = express();
/* Component.jsx */
function loadDataAsProps() { /* ... */ }
loadDataAsProps.ssr = true;

Helper methods

Sometimes you might want to enable SSR preloading for a component, but only for some of its data. Iguazu provides some helper methods, defer and noncritical, to more granularly load data on the server. If you wrap a load function with defer, it will not execute the load function at all and will just return a status of loading. If you wrap a function with noncritical, the load function will execute, but its promise will be caught so that if it rejects it won't cause the Promise.all to reject and return before the other more critical pieces of data have returned.

Example:

import { defer, noncritical } from 'iguazu';

function loadDataAsProps() {
  return {
    clientOnlyData: defer(() => dispatch(loadClientData())),
    tryToLoadOnServerData: noncritical(() => dispatch(loadIffyData())),
  };
}

Iguazu will also pass a parameter to the load function that tells it whether it is running on the server or not. You might want to use this if you expect data to have a specific shape when it is not loaded, because defer will just return data as undefined.

Example:

function MyComponent({ someData }) {
  return <ul>{someData.list.map((item) => <li key={item.toString()}>{item}</li>)}</ul>;
}

function loadDataAsProps() {
  return {
    someData: ({ isServer }) => (isServer ? { data: { list: [] }, status: 'loading' } : dispatch(loadSomeData())),
  };
}

Synchronization

Let's say you have a dynamic dashboard of components that are all responsible for loading their own data, but you want to wait until they are all loaded to render them so that you don't see a bunch of spinners or a partially loaded page. Since Iguazu attaches the loadDataAsProps function as a static, parent components can easily wait until their children's data is loaded before rendering them.

import React from 'react';
import { iguazuReduce } from 'iguazu';
import ComponentA from './ComponentA';
import ComponentB from './ComponentB';

function MyComponent({ isLoading }) {
  if (isLoading()) {
    return (<div>Loading...</div>);
  }

  return (
    <div>
      <ComponentA someParam="someParam" />
      <ComponentB />
    </div>
  );
}

function loadDataAsProps({ store, ownProps }) {
  return {
    ComponentA: () => iguazuReduce(ComponentA.loadDataAsProps)({
      store, ownProps: { someParam: 'someParam' },
    }),
    ComponentB: () => iguazuReduce(ComponentB.loadDataAsProps)({ store, ownProps: {} }),
  };
}

Sequencing

Quite often you need the results of one asynchronous call to get the inputs for another call. One way to do this is by simply using components.

Example:

import React from 'react';
import { connectAsync } from 'iguazu';

function Parent({ isLoading, parent }) {
  if (isLoading()) {
    return <div>Loading Your Profile...</div>;
  }

  return (
    <div>
      <div>
        You:
        <PersonInfo info={parent} />
      </div>
      <KidsContainer parentId={parent.id} />
    </div>
  );
}

function parentLoadDataAsProps({ store: { dispatch } }) {
  return {
    parents: () => dispatch(loadLoggedInParent()),
  };
}

const ParentContainer = connectAsync({ loadDataAsProps: parentLoadDataAsProps })(Parent);

function Kids({ isLoading, kids }) {
  if (isLoading()) {
    return <div>Loading Kids...</div>;
  }

  return (
    <div>
      Kids:
      {kids.map((kid) => (<PersonInfo key={kid.name} info={kid} />))}
    </div>
  );
}

function kidsLoadDataAsProps({ store: { dispatch }, ownProps: { parentId } }) {
  return {
    kids: () => dispatch(loadKidsByParent(parentId)),
  };
}

const KidsContainer = connectAsync({ loadDataAsProps: kidsLoadDataAsProps })(Kids);

function PersonInfo({ info: { name, age } }) {
  return (
    <div>
      <span>
        name:
        {' '}
        {name}
      </span>
      <span>
        age:
        {' '}
        {age}
      </span>
    </div>
  );
}

Suppose you want to synchronize the parent and kid components so that you show a loading spinner until they are both done loading their data. Or maybe you only have one component that needs some sequenced data and it doesn't make sense to create a new component for each nested piece of data. In these cases you can use the load helper, sequence. You can pass it an array of load functions that need to run in order and depend on data returned from previous functions.

Example:

import React from 'react';
import { connectAsync, sequence } from 'iguazu';

function Parent({ isLoading, parent, kids }) {
  if (isLoading()) {
    return <div>Loading Your Profile...</div>;
  }

  return (
    <div>
      <div>
        You:
        <PersonInfo info={parent} />
      </div>
      <Kids kids={kids} />
    </div>
  );
}

function parentLoadDataAsProps({ store: { dispatch } }) {
  const sequenceLoadFunctions = sequence([
    { key: 'parent', handler: () => dispatch(loadLoggedInParent()) },
    { key: 'kids', handler: ({ parent }) => dispatch(loadKidsByParent(parent.id)) },
  ]);

  return {
    ...sequenceLoadFunctions,
  };
}

const ParentContainer = connectAsync({ loadDataAsProps: parentLoadDataAsProps })(Parent);

function Kids({ kids }) {
  return (
    <div>
      Kids:
      {kids.map((kid) => (<PersonInfo key={kid.name} info={kid} />))}
    </div>
  );
}

function PersonInfo({ info: { name, age } }) {
  return (
    <div>
      <span>
        name:
        {name}
      </span>
      <span>
        age:
        {age}
      </span>
    </div>
  );
}

Sequenced function handlers are called with the results from all previous functions in case your inputs need to be derived from more than one previous call.

const sequenceLoadFunctions = sequence([
  { key: 'first', handler: () => dispatch(loadFirst()) },
  { key: 'second', handler: ({ first }) => dispatch(loadSecond(first.someParam)) },
  { key: 'third', handler: ({ first, second }) => dispatch(loadThird(first.someParam, second.anotherParam)) },
]);

If you need to make two calls in parallel before you make a third, you can use a combination of iguazuReduce and sequence to accomplish your goal.

const sequenceLoadFunctions = sequence([
  {
    key: 'first',
    handler: iguazuReduce(() => ({
      firstA: () => dispatch(loadFirstA()),
      firstB: () => dispatch(loadFirstB()),
    })),
  },
  {
    key: 'second', handler: ({ first: { firstA, firstB } }) => dispatch(loadSecond(firstA, firstB)),
  },
]);

Function handlers require the previous calls to succeed to continue to the next by default. In the event a request returns with an error all remaining calls are flagged with the same error. To bypass this default behavior, you can wrap the function handler in noncritical to continue without the previous results.

const sequenceLoadFunctions = sequence([
  { key: 'first', handler: () => dispatch(loadFirst()) },
  { key: 'second', handler: noncritical(({ first }) => dispatch(loadSecond(first.someParam))) },
  { key: 'unrelated', handler: () => dispatch(loadUnrelated()) },
]);

Updating

Iguazu processes updates on Redux state changes by comparing the previous and next responses from loadDataAsProps using shallowequal by default. You are able to declare a comparator function when calling connectAsync to manage how the previous and next responses from loadDataAsProps are compared.

import { deepEqual } from 'fast-equals';

function loadDataAsProps({ store, ownProps }) {
  const { dispatch, getState } = store;
  return {
    myData: () => dispatch(queryToDeeplyNestedData(ownProps.someParam)),
    myOtherData: () => dispatch(queryMyOtherData(getState().someOtherParam)),
  };
}

export default connectAsync({
  loadDataAsProps,
  stateChangeComparator: deepEqual,
})(MyContainer);

Limiting

As some functions called within loadDataAsProps can be expensive when ran on every Redux state change, you are able to declare a limiter function when calling connectAsync. Calls to loadDataAsProps are not limited by default.

function loadDataAsProps({ store, ownProps }) {
  const { dispatch, getState } = store;
  return {
    myData: () => dispatch(expensiveQueryToData(ownProps.someParam)),
    myOtherData: () => dispatch(queryMyOtherData(getState().someOtherParam)),
  };
}

export default connectAsync({
  loadDataAsProps,
  stateChangeLimiter: (onStateChange) => debounce(onStateChange, 100),
})(MyContainer);

Updating and Refreshing Data

In the case that we need to update a remote resource and refresh stale data:

/* MyUpdatingComponent.jsx */
import React, { Component, Fragment } from 'react';
import { compose } from 'redux';
import { connect } from 'react-redux';
import { connectAsync } from 'iguazu';

import { getMyDataAction, updateMyDataAction } from './iguazuActionCreators';

class MyUpdatingComponent extends Component {
  constructor(props) {
    super(props);
    this.state = { message: '' };
  }

  handleClick = () => {
    const { updateMyData, getMyData } = this.props;
    // Send updateMyData request
    const { promise: updateMyDataPromise } = updateMyData('someParam');
    return updateMyDataPromise
      .then(() => {
        // Refresh getMyData to get new results
        const { promise: myDataPromise } = getMyData();
        return myDataPromise;
      })
      .then(() => {
        this.setState({ message: 'Success!' });
      });
  };

  render() {
    const { isLoading, loadedWithErrors, myData } = this.props;
    const { message } = this.state;

    if (isLoading()) {
      return <div>Loading...</div>;
    }

    if (loadedWithErrors()) {
      return <div>Oh no! Something went wrong</div>;
    }

    return (
      <Fragment>
        {message}
        <button type="button" onClick={this.handleClick}>Update</button>
        <h1>My Data</h1>
        {myData}
      </Fragment>
    );
  }
}

// Hook up action creator functions to props to call later
function mapDispatchToProps(dispatch) {
  return {
    // Update some remote resource
    updateMyData: (someParam) => dispatch(updateMyDataAction(someParam)),
    // Fetch some remote resource
    getMyData: () => dispatch(getMyDataAction()),
  };
}

// Hook up data dispatches on component load
function loadDataAsProps({ store }) {
  const { dispatch } = store;
  return {
    // Fetch some remote resource and inject it into props as myData
    myData: () => dispatch(getMyDataAction()),
  };
}

export default compose(
  connect(undefined, mapDispatchToProps),
  connectAsync({ loadDataAsProps })
)(MyUpdatingComponent);

Global Configuration

Iguazu is also capable of consuming global configuration that will be applied to all instances of connectAsync. These options will be applied unless otherwise overridden by providing the equivalent setting in the connectAsync call.

import { shallowEqual, deepEqual } from 'fast-equals';
import { configureIguazu } from 'iguazu';

configureIguazu({
  stateChangeComparator: shallowEqual, // applied globally.
  stateChangeLimiter: (onStateChange) => debounce(onStateChange, 100), // applied globally.
});

/* ... */

function loadDataAsProps({ store, ownProps }) {
  const { dispatch, getState } = store;
  return {
    myData: () => dispatch(queryToDeeplyNestedData(ownProps.someParam)),
    myOtherData: () => dispatch(expensiveQueryToData(ownProps.someParam)),
  };
}

export default connectAsync({
  loadDataAsProps,
  stateChangeComparator: deepEqual, // override global setting.
  stateChangeLimiter: (onStateChange) => debounce(onStateChange, 500), // override global setting.
})(MyContainer);

Known Issues

• Using iguazuReduce within a sequence returns the response to the next handler as an array if the data is not loaded. Pass in promiseAsObject to iguazuReduce to resolve until next major version.

const sequenceLoadFunctions = sequence([
  {
    key: 'first',
    handler: () => iguazuReduce(ComponentA.loadDataAsProps, { promiseAsObject: true })({
      store, ownProps: { someParam: 'someParam' },
    }),
  },
  { key: 'second', handler: ({ first }) => dispatch(loadSecond(first.someParam)) },
]);

🚀 Upgrading

v2.x.x to v3.x.x

• Upgraded to React Redux 7.x.x, Redux 4.x.x, and Redux Thunk 2.x.x
• Using new React Context Consumer for retrieving Redux store.
• Added a ReduxConsumer wrapping component to connectAsync which, may break jest snapshots.
• Removed enableSSR, disableSSR, and isSSR methods in favor of checking for window to determine Server versus Client in SSR mode
• loadDataAsProps functions receive isServer as an argument rather than ssr now.
• Moved react, react-dom, react-redux, redux, and redux-thunk to peerDependencies
• Removed lodash and decreased gzip bundle size from ~9.6kb to ~4.5kb gzipped.
• Iguazu adapters remain compatible, just upgrade dependency on iguazu to ^3.0.0.

🏆 Contributing

We welcome Your interest in the American Express Open Source Community on Github. Any Contributor to any Open Source Project managed by the American Express Open Source Community must accept and sign an Agreement indicating agreement to the terms below. Except for the rights granted in this Agreement to American Express and to recipients of software distributed by American Express, You reserve all right, title, and interest, if any, in and to Your Contributions. Please fill out the Agreement.

Please feel free to open pull requests and see CONTRIBUTING.md to learn how to get started contributing.

🗝️ License

Any contributions made under this project will be governed by the Apache License 2.0.

🗣️ Code of Conduct

This project adheres to the American Express Community Guidelines. By participating, you are expected to honor these guidelines.