When you are working with SPFx, you may choose @pnp/sp library as this provides a fluent API to build your intuitive REST queries and support batching and caching. It is very easy to use. You can find the examples here.

I have used the below snippet to get items from the list.

  1. import pnp from "sp-pnp-js";
  3. pnp.sp.web.lists.getByTitle("Task").select("Title", "ID").items.get().then((items: any[]) => this.setState({
  4. listItems: items
  5. )};
  6. });

After building my SPFx web part, when I deployed in the classic page, it worked as expected. But when I added the same web part to the Modern page, I got the following error.

GET https://mysite.sharepoint.com/SitePages/_api/web 404 (Not Found)The URL contains /SitePages that shouldn't be included.

This issue occurs as the PnP JS API didn’t get the SharePoint context. So, this is how I fixed the issue.

In the props file, add the webpartcontext prop.

  1. import { WebPartContext } from "@microsoft/sp-webpart-base";
  2. export interface IMyListTrainingMasterProps {
  3. description: string;
  4. context:WebPartContext;
  5. }

In the webpart.ts file, add the newly created prop and initialize this.context to get the SharePoint context.

  1. public render(): void {
  2. const element: React.ReactElement<IMyListTrainingMasterProps > = React.createElement(
  3. MyListTrainingMaster,
  4. {
  5. description: this.properties.description,
  6. context: this.context
  7. }
  8. );

Now, the final step! In your component (.tsx file), get the context of the web from the context prop which we created as below.

  1. let web = new Web(this.props.context.pageContext.web.absoluteUrl);
  2. web.lists.getByTitle("Task").select("Title", "ID").items.get().then((items: any[]) => {
  3. this.setState({
  4. listItems: items
  5. });
  6. }
  7. });