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Substring function? #26625
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Hello there, Assume an action that triggers when a PR is made to a branch “ticket-123”, where “ticket-” is fixed. I can easily make a conditional step, using “if: startsWith()”. Question: I need to pass “123” as a parameter to an action: How do I get “123” from “ticket-123”. I cannot seem to find in the docs anything about substring being supported, so there should be some other way. Any help will be greatly appreciated. Thanks! |
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Replies: 5 comments 17 replies
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Unfortunately, there’s currently no built-in substring function. As a workaround, you can use another action and set the substring as an output variable: In this example, I’ve added a step with the ID get-id. That step splits the value that I want to split using cut and then sets it as an output parameter, which can be read and used by subsequent actions. If you’re not familiar with cut, it’s a shell command that splits a string based on a delimiter (-d) and outputs a specific field (-f). You could use any shell we support, or you could even easily use JavaScript with the actions/github-script action: |
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I just wanted to leave a note that set-output is now deprecated: beside that, even though its not that comfortable the proposed solution works and opens the area for a wide range of use-cases! |
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@laeubi only the So to rephrase the shell workaround following the deprecation: - id: get-id
run: |
id=$(echo ${{github.event.client_payload.value}} | cut -d- -f2)
echo "id=$id" >> $GITHUB_OUTPUT
- run: echo "${{steps.get-id.outputs.id}}"and to use the |
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Are there any plans to provide such substring or even regex replace function in the future? This would allow you to use the substring function in all expression locations. |
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@hfhbd As workaround's workaround, you can have a separate job with this step, expose the step output as a job output, and use I agree this is waaaaay more than it should be necessary to achieve this use case! 😔 |
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Yes, I am aware of this workaround I current use. But there is always hope for a better solution using a built-in function. |
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@jclemthank you very much :slight_smile: Using outputs from one step as inputs to another will work perfectly fine as a workaround! |
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Thank you, but, what is even better, you can store this script in file in your repository and test it locally by just running it with required environment variables being defined with |
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Now you can have named runs based on github context, a built-in substring function would be very useful. For example using |
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This is exactly what I was looking to do when I found this. Ansible uses Jinja to handle its "expressions", which basically uses the exact same syntax. Would be cool if we could just use Jinja. |
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I was looking for the same for a while and I didn't find a way. |
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+1, a built-in ability to substring would be very useful. |
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I'm also looking for a way to obtain the first 7 of the github_sha. I was first surprised that this value didn't exist in github contexts or environment variables, and secondly surprised that github yaml doesn't have any substring or length function. The only way to have that first 7, aka short sha, in multiple jobs, is to either recalculate it on every job, or add overhead to pass it between every job, both of which seem cumbersome. |
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like above, use the shell work-around - name: Get short SHA
id: get-short-sha
run: |
id=$(echo ${{github.sha}} | cut -c 1-7)
echo "::set-output name=id::$id"and then use it: tags: ${{steps.get-short-sha.outputs.id}} |
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I'd like to use the short SHA in my This use-case requires a substring function built into the GitHub Actions syntax. |
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@dhirschfeld I'm with you, in matrixes / inputs / workflow names / job names and probably many other places these solutions give us no recourse. |
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Agreed, basic string manipulation functions like substring(and frankly match/replace) would be immensely helpful to have. There was a recent question asking for this here and while it was marked as completed it's a sub-optimal solution (as it required the OP to hard-code all environment names in their workflows). |
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Unfortunately, there’s currently no built-in substring function. As a workaround, you can use another action and set the substring as an output variable:
In this example, I’ve added a step with the ID get-id. That step splits the value that I want to split using cut and then sets it as an output parameter, which can be read and used by subsequent actions.
If you’re not familiar with cut, it’s a shell command that splits a string based on a delimiter (-d) and outputs a specific field (-f). You could use any shell we suppo…