Resting in Peace with SharePoint Rest Apis

Introduction

Are you tired of writing many lines of code to do CRUD functionality? Lets take the simple case of trying to Read a SharePoint List and add items to a SharePoint list.You would have to write two functions using CSOM/JSOM/SSOM:

1. ReadList() 
2. AddListItem()

With the advent of REST in SharePoint, you can focus on your functionality and not on the code/language. All you have to do is to construct the URL based on your needs and reuse the REST CRUD code.

SharePoint team has done a lot of coding and made common functionality available for access from a URL.

You append the SharePoint site URL with REST Url.

Construction of REST Url

The REST Url begins with /_api/

After the api, you specify the Object. Example web, site. For nested objects /web/lists

Lets begin with a simple Url that reads the Site Url.

First, you get the Site Collection  Url and then append that with the Rest Url

Example:

https://abc.sharepoint.com/sites/dev/_api/site/Url

If you open the above Url, you would see a output like below:

<d:Url>https://abc.sharepoint.com</d:Url>

The results are mostly accessed by data.d or data.d.results for multiple items

If you are new to REST, here is a quick explanation on REST basics. REST technology allows developers to write functions using any technology of their choice and publish that as a URL which does the following tasks for a resource/object:

GET- Read the object and returns the results mostly in JSON/Xml format

POST- Get the data details and Add Items

PUT - Update the Object 

DELETE - Delete the Object

SharePoint and PowerShell code to do REST

Lets use PowerShell to get connected to SharePoint URL and do various Read operations. The cool thing is there is only one PowerShell code and the URL alone changes. In regular CSOM coding, you need to remember the Class and the methods to get your job done. in REST, the code remains the same and the URL alone changes.

You can download the code from here.

Here is a quick summary of the PowerShell code to do the CRUD operations.

1. Get connected to SharePoint using SharePoint credentials
2. Add the necessary headers to $headers based on CRUD operation
   1. GET- "Accept", "application/json;odata=verbose"
   2. POST- "X-RequestDigest", $formDigest from /_api/contextinfo
   3. PUT- "X-HTTP-Method", "PUT" or "MERGE"
   4. PUT- "X-HTTP-Method", "DELETE"
3. Invoke-RestMethod -Uri $fullUrl -Headers $headers -Method Post -WebSession $webSession -ContentType "application/json;odata=verbose"

Once, you run the above code, you can start using Read-SPObject,Create-SPObject,Update-SPObject on various SharePoint objects like Site, Lists,Files and many more based on your needs.

Add List Items using REST

Lets start with our original need to read a SharePoint List and add Items to a SharePoint list say PSRestList. 

$targetSite="https://xxx.sharepoint.com/sites/dev"
$User="admin@xxx.onmicrosoft.com"
$restUrl="/_api/web/lists/getbytitle('PSRestList')"
$listsPSRest=Read-SPObject -targetSite $targetSite -User $User -restUrl

Below are the details needed to add a item to a SharePoint list. Note that the data part contains the List Name, List Columns like Title.

#Add List Item
$listName="PSRestList"
$data=@"
{ '__metadata': { 'type': 'SP.Data.$($listName)ListItem' }, 'Title': 'OneTwoThree','CurrencyThangu':'2500' }
"@
$restUrl="/_api/web/lists/GetByTitle('"+$listName+"')/items"
$listItemNew=Create-SPObject -targetSite $targetSite -User $User -restUrl $restUrl -data $data

Summary

As a quick summary, you learnt the following:

1. Basics of REST and its benefits
2. Construction of SharePoint REST Url
3. PowerShell code that Invokes the SharePoint URL
4. Adding a SharePoint List Item using the REST Url.

If you like to learn by watching videos, here is a sample REST demo.