Browser Local Storage using PnPClientStorage

This post has been republished via RSS; it originally appeared at: New blog articles in Microsoft Tech Community.

Why do we need to use browser storage?

You may ask yourself a question that why do I need to use this? what is the advantage of using browser storage? Is it secured? Let us see the features of browser storage.

Almost 90% of the web parts are loaded based on the current logged in users privilege and most of them will use some information from the UPS properties defined. The classical model is to pull the information from UPS on all the web parts whenever is required or to store the information on a SharePoint list to access it easily. Either way requires communication to SharePoint. What if there is a way to reduce the communication and thereby will increase the web part performance? the solution is to use Browser Storage. You can store user property information of the current user in the local storage and then accessing the storage value on all the web parts. You can also schedule a time for the value to refresh.

The browser storage is used mainly for easy access of information that won’t be modified for a long time. Any sensitive data should not be stored using local storage. The storage should be used with caution because overloading the browser local storage will have an impact on the page performance.

Why do we need to use PnPClientStorage?

The normal local storage method is allowed to store the key-value pair where the value should always be the string. PnPClientStorage module provides a thin wrapper over the browser storage options for both local and session storage. If neither option is available then it shims storage with a non-persistent in memory polyfill. Also, most of the boilerplate codes were already written for us to make use of it.

Focus on the Code

Let us start by creating a new web part project using yeoman SharePoint generator, before that create a folder where you want to create the web part. Navigate to that folder and run the below command.

yo /sharepoint

The generator will ask you couple of questions,

Enter the web part name as your solution name, and then select Enter.
Select Create a subfolder with the solution name for where to place the files.
Select Y to allow the solution to be deployed to all sites immediately.
Select N on the question if the solution contains unique permissions.
Enter the web part name
Enter the web part description
Choose the framework as ‘React‘

Once the project is created, install the required PnP modules from npm using the below command. I had created a web part with the name LocalStorage.

npm i @pnp/sp @pnp/common --save-exact

Open the code in VSCode which is my favourite and flexible code editor for SharePoint Framework. You can directly open the project folder from the file menu or use the below command to open the VSCode from the command line.

cd \web part folder\ code .

Based on my web part name, there is a property file created to store the properties for the parent component. In my case it is ILocalStorageProps.ts. Copy the content and delete the file, paste the content in the LocalStorage.tsx file and change the import reference on the tsx and webpart.ts file. Open your webpart.ts file and copy-paste the below code along with the other code in the file, here we are setting up the pnp with the current context.

import { sp } from "@pnp/sp";

Copy-paste the below code under the default class

public onInit(): Promise<void> { return super.onInit().then(_ => { sp.setup(this.context); }); }

Navigate to your webpart.tsx file and copy-paste the below code.

import * as React from 'react'; import styles from './LocalStorage.module.scss'; import { DefaultButton } from 'office-ui-fabric-react/lib/Button'; import { sp } from "@pnp/sp"; import "@pnp/sp/webs"; import "@pnp/sp/site-users"; import { ISiteUserInfo } from '@pnp/sp/site-users/types'; import { PnPClientStorage, dateAdd } from '@pnp/common'; const pnpStorage = new PnPClientStorage(); export interface ILocalStorageProps { description: string; } export interface ILocalStorageState { userinfo: ISiteUserInfo; } export default class LocalStorage extends React.Component<ILocalStorageProps, ILocalStorageState> { constructor(props: ILocalStorageProps) { super(props); this.state = { userinfo: null }; } public _storeCurrentUserInfo = async () => { let currentUserInfo: ISiteUserInfo = pnpStorage.local.get("PnP_UserInfo"); if (!currentUserInfo) { currentUserInfo = await sp.web.currentUser.get(); pnpStorage.local.put('PnP_UserInfo', currentUserInfo, dateAdd(new Date(), 'hour', 1)); } } public _getStoredUserInfo = async () => { let currentUserInfo: ISiteUserInfo = pnpStorage.local.get("PnP_UserInfo"); if (currentUserInfo) this.setState({ userinfo: currentUserInfo }); else this.setState({ userinfo: null }); } public componentDidMount() { pnpStorage.local.deleteExpired(); } public render(): React.ReactElement<ILocalStorageProps> { return ( <div className={styles.localStorage}> <div className={styles.container}> <div className={styles.row}> <div className={styles.column}> <DefaultButton text="Store User Info" onClick={this._storeCurrentUserInfo} /> <DefaultButton text="Get User Info from Storage" onClick={this._getStoredUserInfo} /> <div style={{ display: 'inline-flex' }}> {this.state.userinfo ? ( <div> <p>Title: {this.state.userinfo.Title}</p> <p>EMail: {this.state.userinfo.Email}</p> </div> ) : ( <div>{"Click the button 'Store User Info' to store the user information!"}</div> )} </div> </div> </div> </div> </div> ); } }

Let us see what we have done in the above code.

Note: We have used the local storage in this sample, there is also another storage option named session storage which is not covered in this article. More information can be found in the link here.

We have used the selective imports concept of PnP to import the sp, web and site-users object. We have also imported PnPClientStorage and dateAdd from @pnp/common
We have declared a state interface to hold the user information to display the data in a div.
We have created 2 methods,
- _storeCurrentUserInfo – Store the current logged in user information to the local storage. The method will check whether the information is already stored or not, if not then it is fetched from SharePoint and stored in the storage.
- _getStoredUserInfo – To display the information from the local storage in a div. This method will always pull the information from the storage.
We have declared a componentDidMount method and deleted all the expired values that are stored in the cache. This is the best practice recommended by the PnP team to avoid overloading the storage or leaving unwanted data. We can also automate this by using CacheExpirationInterval, the downside of this implementation is that there will be settimeout method triggered to clear the expired storage.
We have declared two buttons to trigger the above-mentioned methods.

Once the solution is run, you can check your browser console to check whether the information is stored or not.

Source Code

The source code along with other samples can be found in the below GitHub link.

SPFx-Demos

Happy Coding…

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