What is error "inversible formula"

[Humberto_Neira]

Hi,

I am trying to work with formulas and appear the error msg about "inversible formula".

What mean this error msg?

Sample:

On input field, i am trying to incorporate a validation for value. (empty or not; value in range)

thanks

[Dan_Wroblewski]

It has to do with the fact that some properties are 2-way, meaning that you can bind the value to some source so that when the source changes it is reflected in the component AND if the input in the component changes it is reflected in the source.

This you've seen before, like when binding a text component to a variable.

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If I have a star rating component, I can bind the Value property to a page variable, and as expected you can change the page variable and see it in the star rating, or you can click the star rating and "see" it in the page variable.

I can also define a formula as simply the page variable, and it will work because that formula is considered "invertible" -- I know how to change the source, that is, the variable.

But if I set the value as a random value, this value is not "invertible" because there is no way for the value entered into the star rating to be assigned to the source data.

Here is the blog post when they actually introduced the feature of "invertible" formulas as a FEATURE: https://blog.appgyver.com/new-feature-invertible-formulas-b7435c4b6ead

You can see more about this if you open up a composite component. For example, in the star rating component, you can open the template editor and check the property "Value", and you will see that it is specified as a 2-way property.