# Expression parse error: "datum.stack == 'stk1' ? datum.stk1+' '+datum.stk2 : datum.stk2+' '+datum.stk1"

**URL:** https://discuss.elastic.co/t/expression-parse-error-datum-stack-apos-stk1-apos-datum-stk1-apos-apos-datum-stk2-datum-stk2-apos-apos-datum-stk1/183858
**Category:** Kibana
**Tags:** vega
**Created:** [June 2, 2019, 11:05am UTC](https://discuss.elastic.co/t/expression-parse-error-datum-stack-apos-stk1-apos-datum-stk1-apos-apos-datum-stk2-datum-stk2-apos-apos-datum-stk1/183858 "2019-06-02T11:05:27Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![guruprasanth](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/guruprasanth/32/47292_2.png) [@guruprasanth](https://discuss.elastic.co/u/guruprasanth)
#### Post date: [June 2, 2019, 11:05am UTC](https://discuss.elastic.co/t/expression-parse-error-datum-stack-apos-stk1-apos-datum-stk1-apos-apos-datum-stk2-datum-stk2-apos-apos-datum-stk1/183858/1 "2019-06-02T11:05:27Z")

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Hi,  
I have been trying to work on Sankey visualization using vega charts. I tried exactly the same way it's been mentioned in the documentation. [sankey-visualization-with-vega-in-kibana](https://www.elastic.co/blog/sankey-visualization-with-vega-in-kibana). No matter what I do, I'm still facing the expression parser error.  
Expression parse error: "datum.stack == 'stk1' ? datum.stk1+' '+datum.stk2 : datum.stk2+' '+datum.stk1"  
PS: I tried with ELK 6.2,6.7,6.8 and 7.0. Faced the same issue in all

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### Author: ![nickpeihl](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nickpeihl/32/112622_2.png) [@nickpeihl](https://discuss.elastic.co/u/nickpeihl)
#### Post date: [June 3, 2019, 3:53pm UTC](https://discuss.elastic.co/t/expression-parse-error-datum-stack-apos-stk1-apos-datum-stk1-apos-apos-datum-stk2-datum-stk2-apos-apos-datum-stk1/183858/2 "2019-06-03T15:53:53Z")

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Hi @guruprasanth. Looks like we have accidentally included URL encoded apostrophes in the blog post (`&apos;`). If you replace all instances of `&apos;` with `'`, the visualization should work.

I'll have the blog post updated accordingly.

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### Author: ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 1, 2019, 3:53pm UTC](https://discuss.elastic.co/t/expression-parse-error-datum-stack-apos-stk1-apos-datum-stk1-apos-apos-datum-stk2-datum-stk2-apos-apos-datum-stk1/183858/3 "2019-07-01T15:53:59Z")

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