# Built in data key in keychain exp

**URL:** <https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137>\
**Category:** Ignition\
**Tags:** ignition80\
**Created:** [September 28, 2020, 7:05pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137 "2020-09-28T19:05:04Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![dtr019](https://avatars.discourse-cdn.com/v4/letter/d/5f9b8f/32.png) [@dtr019](https://forum.inductiveautomation.com/u/dtr019)\
**Post date:** [September 28, 2020, 7:05pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137/1 "2020-09-28T19:05:04Z")

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Hi, I’m trying to bind the visibility of a text field based on the current page (only want it visible on last page of the report), so I tried this keychain expresion on the visibility property and it did not work: Page==PageMax?“True”:“False”  
Is it my syntax, logic etc. that is incorrect or this is not doable using keychain expressions?  
 ![Keychain_exp_rpt](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/b/9bea1ecc77cd43713ff26455b34aa5dcbc1c58cd.jpeg)

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**Author:** ![dylandaigle](https://avatars.discourse-cdn.com/v4/letter/d/b3f665/32.png) [@dylandaigle](https://forum.inductiveautomation.com/u/dylandaigle)\
**Post date:** [September 28, 2020, 7:47pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137/2 "2020-09-28T19:47:17Z")

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I don’t think you can code in bindings for that property, but you should be able to create a new parameter and have that parameter contain the logic you are trying to implement, then use the parameter as the key binding. The syntax in the parameter expression would be

```auto
if(chart.Page = chart.MaxPage, "True", "False")

```

Set the parameter type to boolean and that should work as you are intending.

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**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [September 28, 2020, 8:09pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137/3 "2020-09-28T20:09:30Z")

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[https://docs.inductiveautomation.com/display/DOC80/Keychain+Expressions](https://docs.inductiveautomation.com/display/DOC80/Keychain+Expressions)  
I think you want a single equals, not a double equals.

EDIT: Nope, I’m wrong.

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<div class="post-metadata">

**Author:** ![dtr019](https://avatars.discourse-cdn.com/v4/letter/d/5f9b8f/32.png) [@dtr019](https://forum.inductiveautomation.com/u/dtr019)\
**Post date:** [September 29, 2020, 12:11pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137/4 "2020-09-29T12:11:06Z")

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👍Thanks for the reply, I tried it as a parameter, didn’t do the trick. What does ‘chart’ in your expression mean. I tried using ReportName.Page, TextField.Page but still not able to sneak in the built-in Page datakey in the expression.

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**Author:** ![code\_skin](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@code\_skin](https://forum.inductiveautomation.com/u/code_skin)\
**Post date:** [September 30, 2020, 4:31pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137/5 "2020-09-30T16:31:46Z")

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@dylandaigle is referring to expression binding syntax while you’re asking about Reports key-chain expression but they are entirely different.

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**Author:** ![code\_skin](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@code\_skin](https://forum.inductiveautomation.com/u/code_skin)\
**Post date:** [September 30, 2020, 4:33pm UTC](https://forum.inductiveautomation.com/t/built-in-data-key-in-keychain-exp/39137/6 "2020-09-30T16:33:38Z")

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Single equals is for assignments and double equals is for comparison (as per the manual).