Two "person or group" columns cannot have the same user SharePoint 2013

Cherry P 21

Hi All,

I have a SharePoint custom list where two "person or group" columns. I need to validate those two columns to make sure they doesn't have the same user. One column is set to allow multiple users and other column is set to allow single user only. I know that we cannot do it with the calculated column.

Can anybody share how do I achieve this? I appreciate all your help!

Thanks,

Accepted answer

Amos Wu-MSFT 4,051

You could add a event receiver(item adding) at your custom list.
My test code for your reference:

 public override void ItemAdding(SPItemEventProperties properties)
            {
                base.ItemAdding(properties);

            object peopleColumn = properties.AfterProperties["SingleUserColumn"];
            SPWeb web = properties.Web;
            SPFieldUserValueCollection objUserFieldValueCol = new SPFieldUserValueCollection(web, properties.AfterProperties["MutipleUserColumn"].ToString());
            for (int i = 0; i < objUserFieldValueCol.Count; i++)
            {
                SPFieldUserValue singlevalue = objUserFieldValueCol[i];

                    if (singlevalue.ToString().Equals(peopleColumn.ToString()))
                    {
                        properties.Cancel = true;
                        properties.ErrorMessage = "Contain two same user";
                        properties.Status = SPEventReceiverStatus.CancelWithError;
                    }

            }

        }

Demo on how to create event receiver for your reference:
https://www.c-sharpcorner.com/article/steps-to-create-item-event-receivers-in-sharepoint-2013-using-c-sharp-server-object-m/

If the response is helpful, please click "Accept Answer" and upvote it.

1 additional answer

Cherry P 21 Reputation points

2020-08-25T12:36:30.157+00:00

Thank you for the response @Amos Wu-MSFT Appreciate it.

I am trying with this code on my dev server and got below error. Can you please help?
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Amos Wu-MSFT 4,051 Reputation points

2020-08-26T01:31:36.433+00:00

Green wavy lines are Compiler Warnings.We don’t need to deal with it, you could press F5 to test whether the code can run correctly.
If you have any updates, please feel free to let us know.

Cherry P 21 Reputation points

2020-08-26T18:59:24.523+00:00

Thank you so much. It worked when adding new item. When I am trying to edit an existing item, it is allowing the same users. Not sure where is the problem?
I had the same code in ItemAdding, ItemUpdating, ItemAdded and ItemUpdated event receivers. I have added the below line in the Elements.xml file but it still allowing the same user in both fields when edit item. Thanks for looking into it.

<Synchronization>Synchronous</Synchronization>

Amos Wu-MSFT 4,051 Reputation points

2020-08-27T08:04:37.823+00:00

Have you modified both columns?

Cherry P 21 Reputation points

2020-08-27T19:47:17.083+00:00

Hi, yes I have modified both columns. EmpA is the single user column and EmpB is the multi user column. Both cannot have same user. When item adding/updating, it should identify and throw an error if both columns have same user. It works and throw an error when adding a new item (so I believe Item adding event works). When editing/updating an item, it is allowing the same user and simply saving the item, not throwing any error (Item Updating event). I want this functionality only for Test list so I have added the URL in the Elements file. Not sure where the issue is. Thank you for all your efforts.
Below is my Item Updating code.

Below is my Elements.xml code.

Cherry P 21 Reputation points

2020-08-27T20:09:02.433+00:00

I found the issue: When I do "Edit item", If I change both column values, it works. If I only change one column value, it doesn't. Simply item is being saved even though both columns have same user. I think we need to change the code in the Item Updating event receiver.

In our case, we don't need to change both columns all the time. Sometime we need to change one column value and sometime the other column, How can we change the code to make it to work? Please advise. Thanks for all your time.

Amos Wu-MSFT 4,051 Reputation points

2020-08-28T09:23:09.42+00:00

In item updating,like the screenshot of my last reply,you need to compare the

properties.AfterProperties["SingleUserColumn"]; properties.ListItem["SingleUserColumn"]; properties.AfterProperties["MutipleUserColumn"]; properties.ListItem["MutipleUserColumn"];

If they are not same,you need to use AfterProperties value.

Cherry P 21 Reputation points

2020-08-28T13:23:28.293+00:00

Could you please provide me the full code what to write in Item Updating? I am not an expert in coding.

Cherry P 21 Reputation points

2020-09-01T03:54:03.47+00:00

Hi @Amos Wu-MSFT . Will you help with this? thank you

Amos Wu-MSFT 4,051 Reputation points

2020-09-01T09:45:07.767+00:00

Sorry for the late reply,I need more time to debug the code.Thank you for your understanding.

Amos Wu-MSFT 4,051 Reputation points

2020-09-02T06:35:45.467+00:00

ItemUpdating code:code.txt
Tip:This is the code written according to my environment user name format, it may need some adjustments in your environment

Cherry P 21 Reputation points

2020-09-02T18:39:20.12+00:00

Hi, thank you so much for your time and efforts on this. The code works and throws error message only when I change the single user column value. When I do "Edit item", change single user column value, it works and throws error message. When I do "Edit Item", only change multi user column -> Click Save, it's not throwing an error message even though both columns have same user, simple saving the item. Here is my code. I am trying the code in test environment. EmpA is the single user column and EmpB is the multi user column.

Amos Wu-MSFT 4,051 Reputation points

2020-09-04T06:17:28.287+00:00

You could try to debug the code(F5) to find out where the problem is.
Because of the differences in our SharePoint environment, the code implementation effect may be different.
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Two "person or group" columns cannot have the same user SharePoint 2013

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