Code Explanation of SharePoint MERGE Request

This document details the structure and functionality of a SharePoint REST API request utilizing the MERGE method to update an item in a list.

Overview

The given code snippet is a REST API call constructed to update specific properties of an item in a SharePoint list titled "Documents." The request is performed using HTTP's MERGE method, which is often used to update part of a resource rather than replace it entirely.

Code Breakdown

URL

https://.sharepoint.com/_api/web/lists/getbytitle('Documents')/items()

• Base URL: This points to the SharePoint site.
• API Endpoint:
  • /web/lists/getbytitle('Documents'): Accesses the list named "Documents".
  • /items(<item id>): References a specific item in the list, where <item id> is the unique identifier of the item you wish to update.

Headers

Headers provide metadata defining the specifics of the HTTP request.

• Content-Type:

  application/json;odata=verbose

  This specifies that the request body is in JSON format and that the response should use OData (Open Data Protocol) in a verbose format.

• If-Match:

  *

  This header indicates that the operation should proceed regardless of any concurrent modifications to the resource. The asterisk symbolizes that any version of the item is acceptable.

• X-HTTP-Method:

  MERGE

  This header specifies that the intended operation to be performed is a MERGE, which will update the item rather than replace it entirely.

Body

The body of the request contains the details of what is to be updated.

{
    "__metadata": {
        "type": "SP.Data.DocumentsItem"
    },
    "Title": "Updated Document Title"
}

• __metadata:

  • This section generally provides context for the backend to understand the entity being referenced.
  • "type": "SP.Data.DocumentsItem" indicates the specific type of item in the SharePoint list.

• Title:

  • Here, the property "Title" is being updated to "Updated Document Title".
  • Only the fields mentioned in the body will be modified in the SharePoint item.

Key Concepts Explained

MERGE Method

The MERGE method is significant in RESTful services as it allows partial updates of resources. This means that only the specified properties in the body are updated without affecting the other existing properties of the resource.

OData Protocol

OData (Open Data Protocol) is a standard that enables the creation and consumption of queryable and interoperable RESTful APIs. It defines conventions for querying and updating data.

SharePoint List Items

In SharePoint, lists represent a collection of data. Each list item is equivalent to a row in a database table, and each property in an item resembles a column.

Additional Examples

For practical application, consider the following examples involving different properties or methods:

Example: Updating Multiple Properties

If you want to update the "Title" and "Description" fields of the same item:

{
    "__metadata": {
        "type": "SP.Data.DocumentsItem"
    },
    "Title": "Updated Document Title",
    "Description": "New Description for the document"
}

Example: Using POST to Insert Item

Instead of MERGE, if you need to create a new item, you would use the POST method:

Headers:

• Content-Type: application/json;odata=verbose

Body:

{
    "__metadata": {
        "type": "SP.Data.DocumentsItem"
    },
    "Title": "New Document Title"
}

Conclusion

This explanation provides a detailed understanding of the SharePoint MERGE API call for updating list items. The breakdown of the URL, headers, and body facilitates a clearer comprehension of how each component functions to update data efficiently within SharePoint. For advanced learning on these topics, exploring resources available through the Enterprise DNA Platform could further enhance understanding and skills.