title: not proper use of react lifecycle
body: <p>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.</p>
  
  <p>When I debug the REST calls are all fine, however the problem is I never get any data rendered on the screen. </p>
  
  <p>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.</p>
  
  <p>This is my webpart code</p>
  
  <pre><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&lt;IFactoryMethodWebPartProps&gt; {
    private _dropdownOptions: IPropertyPaneDropdownOption[];
    private _selectedList: List;
    private _disableDropdown: boolean;
    private _dataProvider: IDataProvider;
    private _factorymethodContainerComponent: FactoryMethod;
  
    protected onInit(): Promise&lt;void&gt; {
      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 &amp;&amp; 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(() =&gt; {
          /*
           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&lt;IFactoryMethodProps &gt; = 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 = &lt;FactoryMethod&gt;ReactDom.render(element, this.domElement);
  
    }
  
    // loads lists from the site and fill the dropdown.
    private loadLists(): Promise&lt;any&gt; {
      return this._dataProvider.getLists()
        .then((lists: List[]) =&gt; {
          // 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) =&gt; {
              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) =&gt; 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&lt;any&gt;[] {
      const fields: IPropertyPaneField&lt;any&gt;[] = [];
  
      // 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()
              }
            ]
          }
        ]
      };
    }
  }
  </code></pre>
  
  <p>This is my component code</p>
  
  <pre><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&lt;IFactoryMethodProps, IFactoryMethodState&gt; {
    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&lt;IFactoryMethodProps&gt; {
      if (this.state.hasError) {
        // you can render any custom fallback UI
        return &lt;h1&gt;Something went wrong.&lt;/h1&gt;;
      } else {
        switch(this.props.listName) {
            case "GenericList":
              // tslint:disable-next-line:max-line-length
              return &lt;this.ListMarqueeSelection items={this.state.DetailsListItemState.items} columns={this.state.columns} /&gt;;
            case "News":
              // tslint:disable-next-line:max-line-length
              return &lt;this.ListMarqueeSelection items={this.state.DetailsNewsListItemState.items} columns={this.state.columns}/&gt;;
            case "Announcements":
              // tslint:disable-next-line:max-line-length
              return &lt;this.ListMarqueeSelection items={this.state.DetailsAnnouncementListItemState.items} columns={this.state.columns}/&gt;;
            case "Directory":
              // tslint:disable-next-line:max-line-length
              return &lt;this.ListMarqueeSelection items={this.state.DetailsDirectoryListItemState.items} columns={this.state.columns}/&gt;;
            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[] }) =&gt; (
        &lt;div&gt;
            &lt;DetailsList
              items={ itemState.items }
              columns={ itemState.columns }
              setKey="set"
              layoutMode={ DetailsListLayoutMode.fixedColumns }
              selectionPreservedOnEmptyClick={ true }
              compact={ true }&gt;
            &lt;/DetailsList&gt;
        &lt;/div&gt;
    )
  
    // 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[]) =&gt; {
  
        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&lt;keyof {}&gt;({
            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
  }
  </code></pre>
  
  <p>I think the rest of the code is not neccesary</p>
  
  <p>Update
  SharepointDataProvider.ts</p>
  
  <pre><code>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&lt;List[]&gt; {
          // 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) =&gt; {
              return response.json();
            })
            .then((json: { value: List[] }) =&gt; {
              return this._lists = json.value;
            });
        }
      }
  </code></pre>
  
  <p>Idataprovider.ts</p>
  
  <pre><code>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&lt;List[]&gt;;
  }
  
  export default IDataProvider;
  </code></pre>