Start form variables and expressions


The expression form element is not populated in the task app when put in a start form and the runtime service method getStartFormModel only takes in a processDefinitionId and a processInstanceId. It also does not pass through data objects that may have been defined on the process page.

I am busy working on adding an options expression, so that one can dynamically define options for drop down elements and it would be nice if this could also work with start forms. So I was wondering whether one could pass through the data objects to the start form as well, and maybe also introduce a method that does take variables?


I have got a similar problem. My process has got a start form, including an expression field to display some information to the user. Additionally some fields should be pre-filled with some values, which can be modified by the user if necessary.

But none of the information set in the process variables are displayed in the start form. The process variables and the corresponding form field got the same id, like “session”.

I tried multiple approaches:

  • Starting the process and provide the variables including values as parameter
  • Setting them in the execution listener (start) on process
  • Setting them in the execution listener (start) on start event

Many thanks for your help,


I am also running into this issue when trying to present a process start form via the REST API - has anyone managed to work out a solution?

@Thomas @rodnaph how did you manage to get the start form (formkey) for the process definition via the API ? I have not managed to get even as far as you appear to have got.

If you get the case/process definitions from the REST API, the only thing it tells is
"startFormDefined": true with no clue on what the start form actually is.

I am working under asusmption that then I POST to start the case/process with form values in

"variables": [
           "value":"This is a variable"

Which I think Thomas said did not work. So waht is the flow in starting case/process with start from via the REST API ?