# Form Reference, Form Properties - Coexistence, Interaction and Expressions

**URL:** <https://forum.flowable.org/t/form-reference-form-properties-coexistence-interaction-and-expressions/1973>\
**Category:** Flowable Engine\
**Created:** [May 3, 2018, 8:08pm UTC](https://forum.flowable.org/t/form-reference-form-properties-coexistence-interaction-and-expressions/1973 "2018-05-03T20:08:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![n0n1ck](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.flowable.org/n0n1ck/32/645_2.png) [@n0n1ck](https://forum.flowable.org/u/n0n1ck)\
**Post date:** [May 3, 2018, 8:08pm UTC](https://forum.flowable.org/t/form-reference-form-properties-coexistence-interaction-and-expressions/1973/1 "2018-05-03T20:08:30Z")

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Hi,

I am using the Form Modeler and Form References on UserTasks - works great.

Lately there was a feature added on the DropDown FormType to define an expression to fill the options.

On most Form Fields it is possible in Form Modeler to set/override the “id” which is also the name of the process variable which the element is mapped to.

What I miss - or cant find … I cannot use an expression as the “id”, means I cannot use e.g. in a Textbox “address.streetname” to access a property “streetname” on a complex type “address” process variable.

I found this is possible to define with FormProperties.

I tried if the Form Reference or Form Definitions somehow can interact with defined Form Properties - didn’t work - perhaps shouldn’t - couldn’t find in docs (… have to say - docs are really good).

I understand Form Fields and Form Modeler is the “new world” - Form Properties is a previous idea to support simple Form Definitions and Process Variable mappings?

Is it possible what I try here?

Would it be a new feature to use an expression on the Form Field “id”?

Thanks and Regards, Andreas.