All files / src getDataFromTree.ts

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import * as React from 'react';
 
export interface Context {
    [key: string]: any;
}
 
interface PromiseTreeArgument {
    rootElement: React.ReactNode;
    rootContext?: Context;
}
interface FetchComponent extends React.Component<any> {
    fetchData(): Promise<void>;
}
 
interface PromiseTreeResult {
    promise: Promise<any>;
    context: Context;
    instance: FetchComponent;
}
 
interface PreactElement<P> {
    attributes: P;
  }
 
function getProps<P>(element: React.ReactElement<P> | PreactElement<P>): P {
    return (element as React.ReactElement<P>).props || (element as PreactElement<P>).attributes;
}
 
function isReactElement(element: React.ReactNode): element is React.ReactElement<any> {
    return !!(element as any).type;
}
 
function isComponentClass(Comp: React.ComponentType<any>): Comp is React.ComponentClass<any> {
    return Comp.prototype && (Comp.prototype.render || Comp.prototype.isReactComponent);
}
function providesChildContext(instance: React.Component<any>): instance is React.Component<any> & React.ChildContextProvider<any> {
    return !!(instance as any).getChildContext;
}
 
// Recurse a React Element tree, running visitor on each element.
// If visitor returns `false`, don't call the element's render function
//   or recurse into its child elements
export function walkTree(element: React.ReactNode, context: Context, visitor: (
      element: React.ReactNode,
      instance: React.Component<any> | null,
      context: Context,
      childContext?: Context,
    ) => boolean | void,
) {
    if (Array.isArray(element)) {
        element.forEach(item => walkTree(item, context, visitor));
        return;
    }
 
    if (!element) {
        return;
    }
 
    // a stateless functional component or a class
    if (isReactElement(element)) {
      if (typeof element.type === 'function') {
        const Comp = element.type;
        const props = Object.assign({}, Comp.defaultProps, getProps(element));
        let childContext = context;
        let child;
 
        // Are we are a react class?
        //   https://github.com/facebook/react/blob/master/src/renderers/shared/stack/reconciler/ReactCompositeComponent.js#L66
        if (isComponentClass(Comp)) {
          const instance = new Comp(props, context);
          // In case the user doesn't pass these to super in the constructor
          instance.props = instance.props || props;
          instance.context = instance.context || context;
          // set the instance state to null (not undefined) if not set, to match React behaviour
          instance.state = instance.state || null;
 
          // Override setState to just change the state, not queue up an update.
          //   (we can't do the default React thing as we aren't mounted "properly"
          //   however, we don't need to re-render as well only support setState in
          //   componentWillMount, which happens *before* render).
          instance.setState = newState => {
            if (typeof newState === 'function') {
              // React's TS type definitions don't contain context as a third parameter for
              // setState's updater function.
              // Remove this cast to `any` when that is fixed.
              newState = (newState as any)(instance.state, instance.props, instance.context);
            }
            instance.state = Object.assign({}, instance.state, newState);
          };
 
          // this is a poor man's version of
          //   https://github.com/facebook/react/blob/master/src/renderers/shared/stack/reconciler/ReactCompositeComponent.js#L181
          if (instance.componentWillMount) {
            instance.componentWillMount();
          }
 
          if (providesChildContext(instance)) {
            childContext = Object.assign({}, context, instance.getChildContext());
          }
 
          if (visitor(element, instance, context, childContext) === false) {
            return;
          }
 
          child = instance.render();
        } else {
          // just a stateless functional
          Iif (visitor(element, null, context) === false) {
            return;
          }
 
          child = Comp(props, context);
        }
 
        if (child) {
          if (Array.isArray(child)) {
            child.forEach(item => walkTree(item, childContext, visitor));
          } else {
            walkTree(child, childContext, visitor);
          }
        }
      } else {
        // a basic string or dom element, just get children
        Iif (visitor(element, null, context) === false) {
          return;
        }
 
        if (element.props && element.props.children) {
            React.Children.forEach(element.props.children, (child: any) => {
            if (child) {
              walkTree(child, context, visitor);
            }
          });
        }
      }
    } else Eif (typeof element === 'string' || typeof element === 'number') {
      // Just visit these, they are leaves so we don't keep traversing.
      visitor(element, null, context);
    }
    // TODO: Portals?
  }
 
function hasFetchDataFunction(instance: React.Component<any>): instance is FetchComponent {
    return typeof (instance as any).fetchData === 'function';
}
               
function isPromise<T>(promise: Object): promise is Promise<T> {
  return typeof (promise as any).then === 'function';
}
                         
function getPromisesFromTree({rootElement, rootContext = {}}: PromiseTreeArgument): PromiseTreeResult[] {
 
    const promises: PromiseTreeResult[] = [];
 
    walkTree(rootElement, rootContext, (_, instance, context, childContext) => {
        if (instance && hasFetchDataFunction(instance)) {
            const promise = instance.fetchData();
            if (isPromise<Object>(promise)) {
                promises.push({promise, context: childContext || context, instance});
                return false;
            }
        }
    });
 
    return promises;
  }
 
export default function getDataFromTree(rootElement: React.ReactNode, rootContext: any = {}): Promise<any> {
    const promises = getPromisesFromTree({rootElement, rootContext});
 
    if (!promises.length) {
        return Promise.resolve();
    }
 
    const errors: any[] = [];
 
    const mappedPromises = promises.map(({promise, context, instance}) => {
        return promise
            .then(_ => getDataFromTree(instance.render(), context))
            .catch(e => errors.push(e));
    });
 
    return Promise.all(mappedPromises).then(_ => {
        if (errors.length > 0) {
          const error =
            errors.length === 1
              ? errors[0]
              : new Error(`${errors.length} errors were thrown when executing your fetchData functions.`);
          error.queryErrors = errors;
          throw error;
        }
      });
}