Use Multiple Selection Columns in Calculated Fields
I recently had a need to create a hyperlink in a custom list and the hyperlink needed to contain parameters that came from a Choice type column that allowed multiple selections. I’m very comfortable using Excel’s string functions (LEFT, RIGHT, MID, LEN, and FIND) to parse strings and I’ve done so many times. However, when I tried to write a formula using the Multiple Selection field, I got an error that said, “One or more column references are not allowed, because the columns are defined as a data type that is not supported in formulas.” Rats! I thought that we might need to write an event receiver with Visual Studio to accomplish my task, but I really wanted to find a way to do it without writing any code. Here is what I did to solve the problem.
In this particular scenario, a department stores information about events in a custom list. There may be one or two people from the department who attend the event. The names of these employees are stored in a column of type Choice that has been set to display as Checkboxes (allow multiple selections).
They use a web based program as part of managing the event. Information about the event is passed to web application as variables in the URL. Two of those parameters are the employees who are attending the event. They want SharePoint to automatically create the URL and modify it if the item changes.
This customer is using our Workflow Essentials product that adds 24 more activities to SharePoint Designer workflows. I decided to make use of two of the Text Capture activity to extract the parts of the string I needed (if you are interested, you can watch a short video on how the Text Capture, Text Replace, and Text Validate actions work).
The Text actions in Workflow Essentials use Regular Expressions to look for values within text (a great place to learn more about Regular Expressions is: http://www.regular-expressions.info/).
When a column is set to allow multiple items to be selected, SharePoint stores them in a plain text format with the items separated by semicolons; you can see this in the example above.
The first Regular Expression I wrote extracted the first word in the My Persons string. The That regular expression is: ^\b[A-Za-z]+\b
The second Regular Expression I wrote extracted the second word in the My Persons string. That regular expression is: \b[A-Za-z]+\b$
Note that regular expressions don’t actually extract anything, but rather returns the part of the original string that matches the given regular expression. These two expressions worked in my case because my strings consisted of single words that consisted only of singe letters and there was a maximum of two words total. If my string had different qualities, I would have to have written totally different regular expressions to match my particular criteria. Writing Regular Expressions is a very valuable, and often under valued, job skill. I’m not an expert at it so I won’t likely be a good source for writing a regular expression for your particular case. Sorry.
Once I had written my Regular Expressions, I was ready to create my solution. I launched SharePoint Designer and created a new workflow on my list that would run when a new item was added or when an item changed.
I added the Text Capture activity first, used my first Regular Expression as pattern and output the captured text to a variable named FirstChoice. Then I added another Text Capture activity where I used my second Regular Expression and captured the matched text to a variable named SecondChoice. Next I added a Build Dynamic String activity where I composed the URL and inserted the two variables in the appropriate place for the URL parameters. Finally, I added a Set Field in Current Item activity where I set the My URL field to the string I had just created. Here is the entire workflow.
As you can tell, Workflow Essentials is a powerful product that can greatly increase the power of your SharePoint Designer workflows. Check it out!