I want to append a string to string type variable.
for build string result in Apply-to-each, Do-Until loop.
1. Notify recent items as a message from Database.
2. Send a message of SharePoint list items as a mail.
3. Send a approve with current task items.
Thank you for your comment, that are nice secnario.
Thank you for sharing nice blog post "JSON cheatsheet for Microsoft Flow"
Yes, I hope to work JSON strings by some actions more easy by Microsoft Flow
I made a workaround - let me know if you think it is good.
If you create two variables, for example 'StringBuild1' and 'StringBuild2', then you can compare then at the beginning of a condition within your "Do until" loop to see which one is shorter. The shorter variable needs to be updated with the most recent new parts of the string you are building. You can build the same actions on the "yes" and "no" sides of the condition, just as long as each side is updating a different variable. I had to use the concat function in a compose action to get the updated string ready, and then in a "set variable" action I was able to use the output of the compose action for the update.
I hope this helps.