Is there any support for join/concat

[echesakov]

Is it possible now to join the elements of sequence to a string?

items:
- foo
- bar

result: ${{ join(items, ';') }}

where result would contain foo;bar string

One of possible scenarios for this could specifying MSBuild semicolon-separated property values using array syntax (instead of a very long string)

[echesakov]

/cc @sbomer @chcosta

[vtbassmatt]

@ericsciple this seems like a decent addition to the expression language. Unless we already have something that will satisfy their scenario? (See the link above.)

[echesakov]

/cc @RussKeldorph

[ericsciple]

I briefly discussed with @vtbassmatt and understand the scenario better now. Makes sense. I'll discuss further with Matt, so we can nail down the details in a spec somewhere (not strictly yaml; the core expression functions are available in other parts of the system too)

[echesakov]

@ericsciple Thank you for considering to add this feature!

Can't wait to have this in any form in the language and remove ugly workaround introduced by dotnet/coreclr#22173

[ericsciple]

@vtbassmatt @echesakovMSFT @sbomer @chcosta what do you think about this proposed behavior:

Join function

• Concatenates all elements in the right parameter array, separated by the left parameter string.
• Min parameters: 2. Max parameters: 2
• Each element in the array is converted to string. Complex objects are converted to empty string.
• If the right parameter is not an array, the result is empty string.

Or would this behavior be better:

• If the right parameter is not an array, the result is the right parameter converted to a string.

[echesakov]

I like the second behavior for the right parameter. In this case, I can think about the function as the following two steps transformation:

1. Convert the right parameter to an array of strings. If the original value is not an array, treat it as a singleton array (of one item).
2. Join the resulting array of strings using the left parameter.

[vtbassmatt]

Yeah, now that you mention it, the silent conversion to an empty string would be confusing.

[ericsciple]

This will roll out with the m148 payload.

[jontreynes]

Is there any support to have an append to array. I see the support here converts an array to a string with a delimiter. However, the use case I'm looking for is to append to an array.

For example

- name: dependsOn
   default:
     - stage1
     - stage2
- name: additionalDependsOn   
    default: stage0
    
 result: ${{append(parameters.dependsOn, additionalDependsOn)}}
 
 # where result is an array [stage1, stage2, stage0]
     

[jontreynes]

Is there any support to have an append to array. I see the support here converts an array to a string with a delimiter. However, the use case I'm looking for is to append to an array.

For example

- name: dependsOn
   default:
     - stage1
     - stage2
- name: additionalDependsOn   
    default: stage0
    
 result: ${{append(parameters.dependsOn, additionalDependsOn)}}
 
 # where result is an array [stage1, stage2, stage0]
     

Update: I've added to feature requests here https://developercommunity.visualstudio.com/t/Function-to-append-to-a-yaml-Array/10166131?space=21&q=function+to+add+to+yaml+array&entry=myfeedback