Update a lookup column through REST API

[mjensen98]

Hi,

I'm struggling to get the correct syntax to update the value of a lookup column of a file in a document library. I've looked at this post (and the article that it points to):

https://powerusers.microsoft.com/t5/Building-Flows/Need-correct-syntax-to-update-lookup-column-prope...

However, there's still quite a difference between the syntax needed here and that for the 'Send an HTTP request to SharePoint' action in Power Automate. I've tried a syntax which just adds the string 'Id' to the end of the lookup column name and sets it through POST request:

However, it throws this error:

Would someone please be able to help me out with this?

Thanks

[Expiscornovus]

Hi @mjensen98,

Is it a single lookup or do you allow multiple lookup values?

If it is a single lookup you could use this approach:

URI

_api/web/lists/getbytitle('@{variables('ListName')}')/Items(1)

Headers

{
  "Content-Type": "application/json;odata=verbose",
  "Accept": "application/json;odata=verbose",
  "IF-MATCH": "*",
  "X-HTTP-Method": "MERGE"
}

Body

{
  "__metadata": {
    "type": "@{outputs('Send_an_HTTP_request_to_SharePoint')?['body/ListItemEntityTypeFullName']}"
  },
  "Doc_ContentId": 1   
  }

[SvampK]

Hi !@Expiscornovus 
Facing some similar problem, although is a multiple value lookup column,

have been googled around but couldn't really find the answer. I wonder if you can answer me?

[Expiscornovus]

Hi @SvampK,

Try this for the body of a multi-lookup field. Keep in mind that the name of the column in this example is Doc_Content and the Id part is added to the end of it.

{
  "__metadata": {
    "type": "@{outputs('Send_an_HTTP_request_to_SharePoint')?['body/ListItemEntityTypeFullName']}"
  },
  "Doc_ContentId": {"results": [1,2] }   
  }

[SvampK]

Thank you so much @Expiscornovus  you are a superhero 🙂

[raflderaf]

And what do I have to replace this with if I want to apply this to my (Multi) lookup Column "DocsToProduct" in my List "Products" which looks up Multiple items in the List "Docs" (Docs-Item IDs: [71,68]) :

@{outputs('Send_an_HTTP_request_to_SharePoint')?['body/ListItemEntityTypeFullName']}

 I dont really see it from this...

[Expiscornovus]

Hi @raflderaf,

Normally the value of the type field is something like SP.Data.<NameOfListEncoded>ListItem. In your case it is probably SP.Data.DocsListItem

In my example I dynamically retrieved the type value from another Send an HTTP request to SharePoint action. In that case I used the below.

Read more about that approach in one of my blogs: https://www.expiscornovus.com/2021/07/10/listitementitytypefullname-within-power-automate/

[DevanKSmith]

You are awesome, was having the same issue and was trying for a day to figure it out. This comment got it working first try!!

[raflderaf]

I have actually also found another solution to my specific problem (I just now realised that this post is about editing a multiple-lookup-column in a document library. I was looking for a solution for a sharepoint list): it doesnt need a syntax as complicated as this. Here is the link: How to update multiple lookup SharePoint column with Power Automate (tomriha.com)

These are screenshot from that website, which held the answer.

[DevanKSmith]

Yeah I actually stumbled upon that blog post as well when looking for a solution. I just ran into the problem that I was getting the Id's dynamically based on other inputs from the beginning of the flow, so it was hard to switch from array to string and add the ;# to the end of each Id except the last one. 

{
  "__metadata": {
    "type": "@{outputs('Send_an_HTTP_request_to_SharePoint')?['body/ListItemEntityTypeFullName']}"
  },
  "Doc_ContentId": {"results": [1,2] }   
  }

This solution worked perfect for me and after results: I put the array of id's.