SPFx - SP PnP JS Not Working On Modern Pages

When you are working with SPFx, you may choose @pnp/sp library as they provide a fluent API to make building your REST queries intuitive and support batching and caching.

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.

import pnp from "sp-pnp-js";

pnp.sp.web.lists.getByTitle("Task").select("Title", "ID").items.get().then((items: any[]) =>          this.setState({
    listItems: items
    )};
});

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.

import { WebPartContext } from "@microsoft/sp-webpart-base";
export interface IMyListTrainingMasterProps {
  description: string;
  context:WebPartContext;
}

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

public render(): void {
    const element: React.ReactElement<IMyListTrainingMasterProps > = React.createElement(
      MyListTrainingMaster,
      {
        description: this.properties.description,
        context: this.context
      }
    );

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

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