Lit-elements, the idiomatic way to write a controlled component - javascript

I'm working with lit-elements via #open-wc and is currently trying to write a nested set of components where the inner component is an input field and some ancestor component has to support some arbitrary rewrite rules like 'numbers are not allowed input'.
What I'm trying to figure out is what the right way to built this is using lit-elements. In React I would use a 'controlled component' see here easily forcing all components to submit to the root component property.
The example below is what I've come up with using Lit-Elements. Is there a better way to do it?
Please note; that the challenge becomes slightly harder since I want to ignore some characters. Without the e.target.value = this.value; at level-5, the input elmement would diverge from the component state on ignored chars. I want the entire chain of components to be correctly in sync, hence the header tags to exemplify.
export class Level1 extends LitElement {
static get properties() {
return {
value: { type: String }
};
}
render() {
return html`
<div>
<h1>${this.value}</h1>
<level-2 value=${this.value} #input-changed=${this.onInput}></level-2>
</div>`;
}
onInput(e) {
this.value = e.detail.value.replace(/\d/g, '');
}
}
...
export class Level4 extends LitElement {
static get properties() {
return {
value: { type: String }
};
}
render() {
return html`
<div>
<h4>${this.value}</h4>
<level-5 value=${this.value}></level-5>
</div>`;
}
}
export class Level5 extends LitElement {
static get properties() {
return {
value: { type: String }
};
}
render() {
return html`
<div>
<h5>${this.value}</h5>
<input .value=${this.value} #input=${this.onInput}></input>
</div>`;
}
onInput(e) {
let event = new CustomEvent('input-changed', {
detail: { value: e.target.value },
bubbles: true,
composed: true
});
e.target.value = this.value;
this.dispatchEvent(event);
}
}
export class AppShell extends LitElement {
constructor() {
super();
this.value = 'initial value';
}
render() {
return html`
<level-1 value=${this.value}></level-1>
`;
}
}
Added later
An alternative approach was using the path array in the event to access the input element directly from the root component.
I think it's a worse solution because it results in a stronger coupling accross the components, i.e. by assuming the child component is an input element with a value property.
onInput(e) {
const target = e.path[0]; // origin input element
this.value = e.path[0].value.replace(/\d/g, '');
// controlling the child elements value to adhere to the colletive state
target.value = this.value;
}


Don't compose your events, handle them in the big parent with your logic there. Have the children send all needed info in the event, try not to rely on target in the parent's event handler.
To receive updates, have your components subscribe in a shared mixin, a la #mishu's suggestion, which uses some state container (here, I present some imaginary state solution)
import { subscribe } from 'some-state-solution';
export const FormMixin = superclass => class extends superclass {
static get properties() { return { value: { type: String }; } }
connectedCallback() {
super.connectedCallback();
subscribe(this);
}
}
Then any component-specific side effects you can handle in updated or the event handler (UI only - do logic in the parent or in the state container)
import { publish } from 'some-state-solution';
class Level1 extends LitElement {
// ...
onInput({ detail: { value } }) {
publish('value', value.replace(/\d/g, ''));
}
}

Related

Lit reactive controllers fail to requestUpdate in nested components

I want to create a basic state management using Lit reactive controllers.
The purpose is to share property values accross the application.
The issue occurs when a controller is attached to a view and to a component nested in the view. When value inside controller changes, the value in the view gets updated, but not in the nested component.
Example:
state.js contains the store logic. A view access the store to create a value and show state value. Nested components also show state value.
state.js
export class StateController {
static get properties() {
return {
state: { type: Object },
host: { type: Object }
}
}
constructor(host) {
// Store a reference to the host
this.host = host;
this.state = {};
// Register for lifecycle updates
host.addController(this);
}
_setStoreValue(property, val) {
this.state[property] = val;
this.host.requestUpdate();
}
}
component.js
import { LitElement, html } from 'lit';
import { StateController } from '../state.js';
export class TestComponent extends LitElement {
static get properties() {
return {
stateCtrl: { type: Object },
state: { type: Object },
};
}
constructor() {
super();
this.stateCtrl = new StateController(this);
this.state = this.stateCtrl.state
}
render() {
return html` Value in component: ${this.state?.test} `;
}
}
customElements.define('test-component', TestComponent);
view.js
import { LitElement, html } from 'lit';
import { StateController } from '../state.js';
import './test-component.js';
export class MonTodo extends LitElement {
static get properties() {
return {
stateCtrl: { type: Object },
state: { type: Object },
};
}
constructor() {
super();
this.stateCtrl = new StateController(this);
this.state=this.stateCtrl.state
}
render() {
return html`
<button #click=${() => this.setValueTest()}>Set value to 3</button>
Value in view: ${this.state?.test}
<h3> Component 1</h3>
<test-component></test-component>
<h3> Component 2</h3>
<test-component></test-component>
`;
}
setValueTest() {
this.stateCtrl._setStoreValue("test", 3)
}
}
customElements.define('mon-todo', MonTodo);
A button click in view.js updates this.state.test in view.js but not in component.js

Since you create a new StateController in both MonTodo and TestComponent, they are two different instances of the StateController which only have their specific component as host.
So the StateController in MonTodo only has MonTodo as a host and only updates that and not TestComponent.
You would need to share one controller with both components and call requestUpdate on both.

Communcation between Web Components

I am building a project with web components and vanilla javascript.
I have a component/module called meal.module - It is the parent component of the components meal-list and meal-search.
meal-list displays multiple meals from an api.
meal-search contains an input field and seachterm as attribute.
meal.module.js
export default class MealModule extends HTMLElement {
connectedCallback() {
this.innerHTML = '<mp-meal-search searchterm=""></mp-meal-search> ' +
'<mp-meal-list></mp-meal-list> ' +
}
}
if (!customElements.get('mp-meal-module')) {
customElements.define('mp-meal-module', EssenModule);
}
meal-list.component
export default class MealListComponent extends HTMLElement {
connectedCallback() {
this.attachShadow({mode: 'open'});
this.shadowRoot.innerHTML = Template.render();
// Renders the meals from api into the template
this.getMeals();
}
(....) more code
}
if (!customElements.get('mp-meal-list')) {
customElements.define('mp-meal-list', MealListComponent);
}
meal-search.component
export default class MealSearchComponent extends HTMLElement {
static get observedAttributes() {
return ['searchterm'];
}
attributeChangedCallback(name, oldVal, newVal) {
if (name === 'searchterm') {
this.doSearch();
}
}
set searchTerm(val) {
this.setAttribute('searchterm', val)
}
get searchTerm() {
return this.getAttribute('searchterm');
}
constructor() {
super();
this.attachShadow({mode: 'open'});
this.shadowRoot.innerHTML = '<input type="text" id="searchterm" value=""/>'
this.shadowRoot.addEventListener('change', (event) =>
this.searchTerm = event.target.value
)
}
doSearch() {
// send signal to MealListComponent for search
}
}
if (!customElements.get('mp-meal-search')) {
customElements.define('mp-meal-search', MealSearchComponent);
}
In the seach-component the SearchTerm is configured as Attribute. Everytime the input field gets changed, the attribute also changes.
Now I want to implement a "searchMeal" function, that always triggers when the attribute in MealSearchComponent changes.
I already tried to import the MealSearchComponent into the MealListComponent. But it does seem to break the rule of components, not having any dependencies.

JavaScript from the outside of the shadow DOM can access the shadow DOM via the element.ShadowRoot property.

How to pass data between lit-element templates?

I am trying to pass data from one component to another. My idea is to have a generic component with buttons that increase or decrease a value and add those specific values ​​to another template.
Here is my code with the buttons:
import { LitElement, html } from 'lit-element';
class ButtonsCounter extends LitElement {
static get properties() {
return {
max: {type: Number},
min: {type: Number},
num: {type: Number},
value: {type: Number},
};
}
constructor() {
super();
this.value = 0;
}
createRenderRoot() {
return this;
}
increment(e) {
e.preventDefault();
if (this.value < this.maxValue) this.value++;
}
decrement(e) {
e.preventDefault();
if (this.value > this.minValue) this.value--;
}
render(){
return html`
<div class="searchCounter" max=${this.maxValue} min=${this.minValue}>
<span num=${this.value}>${this.value}</span>
</div>
`;
}
}
customElements.define('buttons-counter', ButtonsCounter);
Here is the template where I want to add the data that will go to the previous template:
import { LitElement, html } from 'lit-element';
import './buttons-counter'
class SelectOption extends LitElement {
constructor() {
super();
this.num = 0;
this.max = 5;
this.min = 0;
}
createRenderRoot() {
return this;
}
render(){
return html`
<buttons-counter .max="${this.max}" .min="${this.min}" .num="${this.num}"></buttons-counter>
`;
};
}
customElements.define('select-option', SelectOption);
I've tried different ways but none works. Any idea?

It looks like you're mixing up value with num, maxValue with max, and minValue with min.
You'll also likely want some text inside your a tags so that they're reasonably clickable. Technically, they should also be button tags (styled to your liking), as a tags are considered for linking to parts of a page or to another page (see https://stackoverflow.com/a/37148542/6090140 for more details). You then will not need e.preventDefault(); inside decrement and increment.
<button #click="${this.decrement}">-</button>

fieldChanged() method not called when "field.property" is changed from child component

This is my parent view model and view.
export class Parent {
#observable field;
fieldChanged() {
console.log('field has been changed');
}
}
<template>
<child-component field.two-way="field" />
</template>
When I do
this.field.property = 'new value';
in child-component, fieldChanged method is not called.
Note that field is type of object. With primitive types it works well.
Can I do something to make this work on object types?

If you want to observe a property of an object, you can use the bindingEngine:
import { BindingEngine, inject } from 'aurelia-framework';
#inject(BindingEngine)
export class Parent {
field = {
property: ''
}
constructor(bindingEngine) {
this.bindingEngine = bindingEngine;
}
attached() {
this.subscription = this.bindingEngine.propertyObserver(this.field, 'property')
.subscribe((newValue, oldValue) => {
// do your logic here
})
}
detached() {
// Dispose subscription to avoid memory leak
this.subscription.dispose();
}
}

You can use BindingEngine.expressionObserver method to observe a path, instead of a single property
const observer = bindingEngine
.expressionObserver(this /* or any object */, 'field.property')
.subscribe(newValue => console.log('new field.property is:', newValue))
And remember to call observer.dispose() later when no longer needed.

you probably didn't declare the binding in the child component:
import {bindable} from 'aurelia-framework';
export class ChildComponent
{
#bindable field;
/* DO whatever you want*/
}
btw:
in your code you should have this.field = 'new value'; and not field = 'new value';

not proper use of react lifecycle

I have a Sharepoint Framework webpart which basically has a property side bar where I can select the Sharepoint List, and based on the selection it will render the list items from that list into an Office UI DetailsList Component.
When I debug the REST calls are all fine, however the problem is I never get any data rendered on the screen.
so If I select GenericList it should query Generic LIst, if I select Directory it should query the Directory list, however when I select Directory it still says that the selection is GenericList, not directory.
This is my webpart code
import * as React from "react";
import * as ReactDom from "react-dom";
import { Version } from "#microsoft/sp-core-library";
import {
BaseClientSideWebPart,
IPropertyPaneConfiguration,
PropertyPaneTextField,
PropertyPaneDropdown,
IPropertyPaneDropdownOption,
IPropertyPaneField,
PropertyPaneLabel
} from "#microsoft/sp-webpart-base";
import * as strings from "FactoryMethodWebPartStrings";
import FactoryMethod from "./components/FactoryMethod";
import { IFactoryMethodProps } from "./components/IFactoryMethodProps";
import { IFactoryMethodWebPartProps } from "./IFactoryMethodWebPartProps";
import * as lodash from "#microsoft/sp-lodash-subset";
import List from "./components/models/List";
import { Environment, EnvironmentType } from "#microsoft/sp-core-library";
import IDataProvider from "./components/dataproviders/IDataProvider";
import MockDataProvider from "./test/MockDataProvider";
import SharePointDataProvider from "./components/dataproviders/SharepointDataProvider";
export default class FactoryMethodWebPart extends BaseClientSideWebPart<IFactoryMethodWebPartProps> {
private _dropdownOptions: IPropertyPaneDropdownOption[];
private _selectedList: List;
private _disableDropdown: boolean;
private _dataProvider: IDataProvider;
private _factorymethodContainerComponent: FactoryMethod;
protected onInit(): Promise<void> {
this.context.statusRenderer.displayLoadingIndicator(this.domElement, "Todo");
/*
Create the appropriate data provider depending on where the web part is running.
The DEBUG flag will ensure the mock data provider is not bundled with the web part when you package the
solution for distribution, that is, using the --ship flag with the package-solution gulp command.
*/
if (DEBUG && Environment.type === EnvironmentType.Local) {
this._dataProvider = new MockDataProvider();
} else {
this._dataProvider = new SharePointDataProvider();
this._dataProvider.webPartContext = this.context;
}
this.openPropertyPane = this.openPropertyPane.bind(this);
/*
Get the list of tasks lists from the current site and populate the property pane dropdown field with the values.
*/
this.loadLists()
.then(() => {
/*
If a list is already selected, then we would have stored the list Id in the associated web part property.
So, check to see if we do have a selected list for the web part. If we do, then we set that as the selected list
in the property pane dropdown field.
*/
if (this.properties.spListIndex) {
this.setSelectedList(this.properties.spListIndex.toString());
this.context.statusRenderer.clearLoadingIndicator(this.domElement);
}
});
return super.onInit();
}
// render method of the webpart, actually calls Component
public render(): void {
const element: React.ReactElement<IFactoryMethodProps > = React.createElement(
FactoryMethod,
{
spHttpClient: this.context.spHttpClient,
siteUrl: this.context.pageContext.web.absoluteUrl,
listName: this._dataProvider.selectedList === undefined ? "GenericList" : this._dataProvider.selectedList.Title,
dataProvider: this._dataProvider,
configureStartCallback: this.openPropertyPane
}
);
// reactDom.render(element, this.domElement);
this._factorymethodContainerComponent = <FactoryMethod>ReactDom.render(element, this.domElement);
}
// loads lists from the site and fill the dropdown.
private loadLists(): Promise<any> {
return this._dataProvider.getLists()
.then((lists: List[]) => {
// disable dropdown field if there are no results from the server.
this._disableDropdown = lists.length === 0;
if (lists.length !== 0) {
this._dropdownOptions = lists.map((list: List) => {
return {
key: list.Id,
text: list.Title
};
});
}
});
}
protected get dataVersion(): Version {
return Version.parse("1.0");
}
protected onPropertyPaneFieldChanged(propertyPath: string, oldValue: any, newValue: any): void {
/*
Check the property path to see which property pane feld changed. If the property path matches the dropdown, then we set that list
as the selected list for the web part.
*/
if (propertyPath === "spListIndex") {
this.setSelectedList(newValue);
}
/*
Finally, tell property pane to re-render the web part.
This is valid for reactive property pane.
*/
super.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);
}
// sets the selected list based on the selection from the dropdownlist
private setSelectedList(value: string): void {
const selectedIndex: number = lodash.findIndex(this._dropdownOptions,
(item: IPropertyPaneDropdownOption) => item.key === value
);
const selectedDropDownOption: IPropertyPaneDropdownOption = this._dropdownOptions[selectedIndex];
if (selectedDropDownOption) {
this._selectedList = {
Title: selectedDropDownOption.text,
Id: selectedDropDownOption.key.toString()
};
this._dataProvider.selectedList = this._selectedList;
}
}
// we add fields dynamically to the property pane, in this case its only the list field which we will render
private getGroupFields(): IPropertyPaneField<any>[] {
const fields: IPropertyPaneField<any>[] = [];
// we add the options from the dropdownoptions variable that was populated during init to the dropdown here.
fields.push(PropertyPaneDropdown("spListIndex", {
label: "Select a list",
disabled: this._disableDropdown,
options: this._dropdownOptions
}));
/*
When we do not have any lists returned from the server, we disable the dropdown. If that is the case,
we also add a label field displaying the appropriate message.
*/
if (this._disableDropdown) {
fields.push(PropertyPaneLabel(null, {
text: "Could not find tasks lists in your site. Create one or more tasks list and then try using the web part."
}));
}
return fields;
}
private openPropertyPane(): void {
this.context.propertyPane.open();
}
protected getPropertyPaneConfiguration(): IPropertyPaneConfiguration {
return {
pages: [
{
header: {
description: strings.PropertyPaneDescription
},
groups: [
{
groupName: strings.BasicGroupName,
/*
Instead of creating the fields here, we call a method that will return the set of property fields to render.
*/
groupFields: this.getGroupFields()
}
]
}
]
};
}
}
This is my component code
//#region Imports
import * as React from "react";
import styles from "./FactoryMethod.module.scss";
import { IFactoryMethodProps } from "./IFactoryMethodProps";
import {
IDetailsListItemState,
IDetailsNewsListItemState,
IDetailsDirectoryListItemState,
IDetailsAnnouncementListItemState,
IFactoryMethodState
} from "./IFactoryMethodState";
import { IListItem } from "./models/IListItem";
import { IAnnouncementListItem } from "./models/IAnnouncementListItem";
import { INewsListItem } from "./models/INewsListItem";
import { IDirectoryListItem } from "./models/IDirectoryListItem";
import { escape } from "#microsoft/sp-lodash-subset";
import { SPHttpClient, SPHttpClientResponse } from "#microsoft/sp-http";
import { ListItemFactory} from "./ListItemFactory";
import { TextField } from "office-ui-fabric-react/lib/TextField";
import {
DetailsList,
DetailsListLayoutMode,
Selection,
buildColumns,
IColumn
} from "office-ui-fabric-react/lib/DetailsList";
import { MarqueeSelection } from "office-ui-fabric-react/lib/MarqueeSelection";
import { autobind } from "office-ui-fabric-react/lib/Utilities";
import PropTypes from "prop-types";
//#endregion
export default class FactoryMethod extends React.Component<IFactoryMethodProps, IFactoryMethodState> {
constructor(props: IFactoryMethodProps, state: any) {
super(props);
this.setInitialState();
}
// lifecycle help here: https://staminaloops.github.io/undefinedisnotafunction/understanding-react/
//#region Mouting events lifecycle
// the data returned from render is neither a string nor a DOM node.
// it's a lightweight description of what the DOM should look like.
// inspects this.state and this.props and create the markup.
// when your data changes, the render method is called again.
// react diff the return value from the previous call to render with
// the new one, and generate a minimal set of changes to be applied to the DOM.
public render(): React.ReactElement<IFactoryMethodProps> {
if (this.state.hasError) {
// you can render any custom fallback UI
return <h1>Something went wrong.</h1>;
} else {
switch(this.props.listName) {
case "GenericList":
// tslint:disable-next-line:max-line-length
return <this.ListMarqueeSelection items={this.state.DetailsListItemState.items} columns={this.state.columns} />;
case "News":
// tslint:disable-next-line:max-line-length
return <this.ListMarqueeSelection items={this.state.DetailsNewsListItemState.items} columns={this.state.columns}/>;
case "Announcements":
// tslint:disable-next-line:max-line-length
return <this.ListMarqueeSelection items={this.state.DetailsAnnouncementListItemState.items} columns={this.state.columns}/>;
case "Directory":
// tslint:disable-next-line:max-line-length
return <this.ListMarqueeSelection items={this.state.DetailsDirectoryListItemState.items} columns={this.state.columns}/>;
default:
return null;
}
}
}
public componentDidCatch(error: any, info: any): void {
// display fallback UI
this.setState({ hasError: true });
// you can also log the error to an error reporting service
console.log(error);
console.log(info);
}
// componentDidMount() is invoked immediately after a component is mounted. Initialization that requires DOM nodes should go here.
// if you need to load data from a remote endpoint, this is a good place to instantiate the network request.
// this method is a good place to set up any subscriptions. If you do that, don’t forget to unsubscribe in componentWillUnmount().
// calling setState() in this method will trigger an extra rendering, but it is guaranteed to flush during the same tick.
// this guarantees that even though the render() will be called twice in this case, the user won’t see the intermediate state.
// use this pattern with caution because it often causes performance issues. It can, however, be necessary for cases like modals and
// tooltips when you need to measure a DOM node before rendering something that depends on its size or position.
public componentDidMount(): void {
this._configureWebPart = this._configureWebPart.bind(this);
this.readItemsAndSetStatus();
}
//#endregion
//#region Props changes lifecycle events (after a property changes from parent component)
// componentWillReceiveProps() is invoked before a mounted component receives new props.
// if you need to update the state in response to prop
// changes (for example, to reset it), you may compare this.props and nextProps and perform state transitions
// using this.setState() in this method.
// note that React may call this method even if the props have not changed, so make sure to compare the current
// and next values if you only want to handle changes.
// this may occur when the parent component causes your component to re-render.
// react doesn’t call componentWillReceiveProps() with initial props during mounting. It only calls this
// method if some of component’s props may update
// calling this.setState() generally doesn’t trigger componentWillReceiveProps()
public componentWillReceiveProps(nextProps: IFactoryMethodProps): void {
if(nextProps.listName !== this.props.listName) {
this.readItemsAndSetStatus();
}
}
//#endregion
//#region private methods
private _configureWebPart(): void {
this.props.configureStartCallback();
}
public setInitialState(): void {
this.state = {
hasError: false,
status: this.listNotConfigured(this.props)
? "Please configure list in Web Part properties"
: "Ready",
columns:[],
DetailsListItemState:{
items:[]
},
DetailsNewsListItemState:{
items:[]
},
DetailsDirectoryListItemState:{
items:[]
},
DetailsAnnouncementListItemState:{
items:[]
},
};
}
// reusable inline component
private ListMarqueeSelection = (itemState: {columns: IColumn[], items: IListItem[] }) => (
<div>
<DetailsList
items={ itemState.items }
columns={ itemState.columns }
setKey="set"
layoutMode={ DetailsListLayoutMode.fixedColumns }
selectionPreservedOnEmptyClick={ true }
compact={ true }>
</DetailsList>
</div>
)
// read items using factory method pattern and sets state accordingly
private readItemsAndSetStatus(): void {
this.setState({
status: "Loading all items..."
});
const factory: ListItemFactory = new ListItemFactory();
factory.getItems(this.props.spHttpClient, this.props.siteUrl, this.props.listName)
.then((items: any[]) => {
var myItems: any = null;
switch(this.props.listName) {
case "GenericList":
myItems = items as IListItem[];
break;
case "News":
myItems = items as INewsListItem[];
break;
case "Announcements":
myItems = items as IAnnouncementListItem[];
break;
case "Directory":
myItems = items as IDirectoryListItem[];
break;
}
const keyPart: string = this.props.listName === "GenericList" ? "" : this.props.listName;
// the explicit specification of the type argument `keyof {}` is bad and
// it should not be required.
this.setState<keyof {}>({
status: `Successfully loaded ${items.length} items`,
["Details" + keyPart + "ListItemState"] : {
myItems
},
columns: buildColumns(myItems)
});
});
}
private listNotConfigured(props: IFactoryMethodProps): boolean {
return props.listName === undefined ||
props.listName === null ||
props.listName.length === 0;
}
//#endregion
}
I think the rest of the code is not neccesary
Update
SharepointDataProvider.ts
import {
SPHttpClient,
SPHttpClientBatch,
SPHttpClientResponse
} from "#microsoft/sp-http";
import { IWebPartContext } from "#microsoft/sp-webpart-base";
import List from "../models/List";
import IDataProvider from "./IDataProvider";
export default class SharePointDataProvider implements IDataProvider {
private _selectedList: List;
private _lists: List[];
private _listsUrl: string;
private _listItemsUrl: string;
private _webPartContext: IWebPartContext;
public set selectedList(value: List) {
this._selectedList = value;
this._listItemsUrl = `${this._listsUrl}(guid'${value.Id}')/items`;
}
public get selectedList(): List {
return this._selectedList;
}
public set webPartContext(value: IWebPartContext) {
this._webPartContext = value;
this._listsUrl = `${this._webPartContext.pageContext.web.absoluteUrl}/_api/web/lists`;
}
public get webPartContext(): IWebPartContext {
return this._webPartContext;
}
// get all lists, not only tasks lists
public getLists(): Promise<List[]> {
// const listTemplateId: string = '171';
// const queryString: string = `?$filter=BaseTemplate eq ${listTemplateId}`;
// const queryUrl: string = this._listsUrl + queryString;
return this._webPartContext.spHttpClient.get(this._listsUrl, SPHttpClient.configurations.v1)
.then((response: SPHttpClientResponse) => {
return response.json();
})
.then((json: { value: List[] }) => {
return this._lists = json.value;
});
}
}
Idataprovider.ts
import { IWebPartContext } from "#microsoft/sp-webpart-base";
import List from "../models/List";
import {IListItem} from "../models/IListItem";
interface IDataProvider {
selectedList: List;
webPartContext: IWebPartContext;
getLists(): Promise<List[]>;
}
export default IDataProvider;

When the list name changes, you're invoking readItemsAndSetStatus:
public componentWillReceiveProps(nextProps: IFactoryMethodProps): void {
if(nextProps.listName !== this.props.listName) {
this.readItemsAndSetStatus();
}
}
However, readItemsAndSetStatus doesn't take a parameter, and continues to use this.props.listName, which hasn't changed yet.
private readItemsAndSetStatus(): void {
...
const factory: ListItemFactory = new ListItemFactory();
factory.getItems(this.props.spHttpClient, this.props.siteUrl, this.props.listName)
...
}
Try passing nextProps.listName to readItemsAndSetStatus:
public componentWillReceiveProps(nextProps: IFactoryMethodProps): void {
if(nextProps.listName !== this.props.listName) {
this.readItemsAndSetStatus(nextProps.listName);
}
}
Then either use the incoming parameter, or default to this.props.listName:
private readItemsAndSetStatus(listName): void {
...
const factory: ListItemFactory = new ListItemFactory();
factory.getItems(this.props.spHttpClient, this.props.siteUrl, listName || this.props.listName)
...
}

In your first "webpart code", the onInit() method returns before loadLists() finishes:
onInit() {
this.loadLists() // <-- Sets this._dropdownOptions
.then(() => {
this.setSelectedList();
});
return super.onInit(); // <-- Doesn't wait for the promise to resolve
}
This means that getGroupFields() might not have data for _dropdownOptions. That means that getPropertyPaneConfiguration() might not have the right data.
I'm not positive that's the problem, or the only problem. I don't have any experience with SharePoint, so take all of this with a grain of salt.
I see that in the react-todo-basic they are doing the same thing you are.
However, elsewhere I see people performing additional actions within the super.onInit Promise:
react-list-form
react-sp-pnp-js-property-decorator

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