This is the second part in my series on developing code to modify external lists.  In this post we will be updating SharePoint external lists using CSOM.  Like standard PowerShell there is not any real difference in the execution of the update between internal and external lists.  What is different is how the data is obtained when performing an update, read or deletion.  Like PowerShell, in CSOM you can find the item you wish to access using the ID.  However, because there isn’t a list ID field in an external list you have to query to find the item(s) you need.  You could loop through each item in the list until you find one with the particular attributes you are looking for, but that is not efficient and it may be difficult if the fields you are checking have multiple rows with the same values.  So brush up on your CAML query.

Using CSOM to Manage Data in Internal Lists

CSOM has come a long way since its inception in SharePoint 2010.  I would still be recommending it over REST except that unlike REST things are a bit different between on-prem and SharePoint Online CSOM versions (you need a different versions for each).  This post isn’t meant as a discussion on the pros and cons of REST vs CSOM though (You can get more information here if you are curious though).  CSOM is probably a little more complicated than the PowerShell examples I provided in my previous post, but one you get the hang of loading the data you need before working with it the process is pretty easy.

To show you what we are going to be doing here’s the list we will be starting off with:

Updating SharePoint External Lists using CSOM - Internal List Before Code

Using this config:

we will update the list with the following code:

Running the code:

Updating SharePoint External Lists using CSOM - Internal List Running Code

The list gets updated as expected:

Updating SharePoint External Lists using CSOM - Internal List After Code

 

Using CSOM to Update External Lists

As I stated above, the code is very similar to internal lists except there you need to use CAML Query to access the items.  Note with CSOM you don’t have to define the ServiceContext scope.

The list:

Updating SharePoint External Lists using CSOM - External List Before Code

Will get modified based on this config:

Reviewing the code, note the insertion of the CAML Query to find a specific item.  One important thing to note with the CAML query.  You have to use the name of the function used to define the Read-List process in the External Content Type

Running the code:

Updating SharePoint External Lists using CSOM - External List Running Code

Leaves us with the following updated list:

Updating SharePoint External Lists using CSOM - External List After Code

So again, other than gathering the item to update, managing items in an external list is very similar to managing items in an internal list.  My next post we will cover the differences in manipulating internal and external items with REST.

Thanks for reading!!