# Tag history as Expression

**URL:** <https://forum.inductiveautomation.com/t/tag-history-as-expression/80511>\
**Category:** Ignition\
**Tags:** perspective\
**Created:** [October 16, 2023, 5:52am UTC](https://forum.inductiveautomation.com/t/tag-history-as-expression/80511 "2023-10-16T05:52:45Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![David\_Kranjc](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/david_kranjc/32/43007_2.png) [@David\_Kranjc](https://forum.inductiveautomation.com/u/David_Kranjc)\
**Post date:** [October 16, 2023, 5:52am UTC](https://forum.inductiveautomation.com/t/tag-history-as-expression/80511/1 "2023-10-16T05:52:45Z")

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Hello,  
I am trying to show data through Tag History with expression mode. I want to have path linked to one of params of popup screen.  
I did configure as example as in help but I get an error (see picture for more detail).

Has anyone managed to make a connection this way?

 ![java_165](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/d/9dfe76865302e5e883b1cd54d053727842194ee2.png)

Thank you very much and best regards.

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**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\
**Post date:** [October 16, 2023, 7:50am UTC](https://forum.inductiveautomation.com/t/tag-history-as-expression/80511/2 "2023-10-16T07:50:31Z")

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I think the problem is that Ignition is expecting an **expression** but you have supplied a **list**. That would work in Python but not in the expression language.

The documentation says to create the list as a custom property and then reference that in the expression. From the manual (with emphasis changed by me):

1. Create a **custom property named**  **Key** on a chart component that is an Array type.

2. Copy and paste the JSON below **into this Key property**.

3. JSON for Key Array  
[Sample JSON removed.]

4. Open the property binding on your chart and select the Tag History binding type.

5. Select the **Expression** radio button to create your own tag structure.

6. Click on the **property selector button** on the right and **find your new custom property**.

7. Click OK in the lower right.

[https://docs.inductiveautomation.com/display/DOC81/Tag+History+Bindings+in+Perspective#TagHistoryBindingsinPerspective-UsingDynamicTagPaths](https://docs.inductiveautomation.com/display/DOC81/Tag+History+Bindings+in+Perspective#TagHistoryBindingsinPerspective-UsingDynamicTagPaths)

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<div class="post-metadata">

**Author:** ![David\_Kranjc](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/david_kranjc/32/43007_2.png) [@David\_Kranjc](https://forum.inductiveautomation.com/u/David_Kranjc)\
**Post date:** [October 17, 2023, 7:49am UTC](https://forum.inductiveautomation.com/t/tag-history-as-expression/80511/3 "2023-10-17T07:49:37Z")

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Thank you for all information. I read the instructions too quickly at first