Updating list items in sharepoint
Build a dictionary that will contain the headers for the REST call.We willl call this dictionary POST_Request Header and add the attributes according to the picture below Accept: application/json;odata=verbose content-type: application/json;odata=verbose X-HTTP-Method: MERGE IF-MATCH: * According to Share Point 2013 REST guide, when you are trying to update an item you do need to use the term X-HTTP-Method in the REST header.If the web service call successfully updates the item, your response code will be the string “No Conten”, otherwise you will have the error message.Recently, in one of my projects there was a requirement to create a Share Point list workflow that triggers when an item is created, and that should result in creating a new list item on another Share Point list which is created on some other Share Point instance.One of the most celebrated new feature by the developers is the possibilities to make REST call directly from the workflows.With that, the workflows can be easily integrated with other system and even with other Share Point sites.I've a couple of further suggestions: Can you not associate the workflow with the ' Other' list as that seems to be where most of the 'work' is happening?If this is not possible, then I feel you will need to create a specific 'lookup' field in the target list - concatenating the Col A & B values, then perform the lookup against that.
Otherwise you should obtain the etag value of a list item by performing a GET request before update the item. Create another dictionary called POST_Metadata where we will store the type of the item You should find the correct data type for the item you are trying to update. The data type name might change so don’t assume it is always your list name.
Just a simple search on the internet and you can find several examples illustrating how to call external JSON web services and how to read and write Share Point lists items using the Share Point REST API as well.
However, update an existing item in a Share Point lists has some tricks which we will show you in this post.
Failing that I think you'll need to look at a coded solution Alright ladies and gentlemen here's the answer: I was able to use an HTTP call to get and loop through the items on the 2nd list.
Then I was able to check the values of each column on each item and find the specific item I needed.