How get the latest value in pick list - azure-devops

Question

I'm trying to develop an extension/pipeline task for Azure DevOps for release gates. Not getting how to bind the the latest value to the pick list as shown here:
Each time a build completes, pick list should have latest build Id as the selected value.
Here is the code snippet i tried,
This creates a pick list
{
"name": "buildId",
"type": "pickList",
"label": "Artifact",
"required": true,
"defaultValue": "Latest",
"properties": {
"DisableManageLink": "True",
"EditableOptions": "True"
}
"helpMarkDown": "Build Artifacts"
},
this binds the values for the picklist
{
"target": "buildId",
"endpointId": "tfs:teamfoundation",
"endpointUrl": "{{endpoint.url}}/{{system.teamProject}}/_apis/build/builds?api-version=5.0",
"resultSelector": "jsonpath:$.value[*]",
"resultTemplate": "{ \"Value\" : \"{{{id}}}\", \"DisplayValue\" : \"{{{buildNumber}}} \" }"
}
Let me know if there are any way to get this.

Answer 1

I afraid you will need to implement your own code methods to bind latest value to the latest buildid.
For example in Publish build artifacts task. The latest build id is retrieved according to the selected value(ie. latest) of field buildVersionToDownload: See below:
buildVersionToDownload has three options.
{
"name": "buildVersionToDownload",
"type": "pickList",
"label": "Build version to download",
"defaultValue": "latest",
"visibleRule": "buildType == specific",
"required": true,
"options": {
"latest": "Latest",
"latestFromBranch": "Latest from specific branch and specified Build Tags",
"specific": "Specific version"
}
}
If the buildVersionToDownload value is selected as specific. Then it is required to select the build id in the Build picklist.
{
"name": "buildId",
"type": "pickList",
"label": "Build",
"defaultValue": "",
"required": true,
"visibleRule": "buildType == specific && buildVersionToDownload == specific",
"properties": {
"EditableOptions": "True",
"DisableManageLink": "True"
},
"helpMarkDown": "The build from which to download the artifacts"
}
buildVersionToDownload is not bound to dataSource, only buildId is bound:
{
"endpointId": "tfs:teamfoundation",
"target": "buildId",
"endpointUrl": "{{endpoint.url}}/{{project}}/_apis/build/builds?definitions={{definition}}&resultFilter=succeeded,partiallySucceeded&$top=200",
"resultSelector": "jsonpath:$.value[*]",
"parameters": {
"project": "$(project)",
"definition": "$(definition)"
},
"resultTemplate": "{ \"Value\" : \"{{{id}}}\", \"DisplayValue\" : \"{{{buildNumber}}}\" }"
}
See here for more information.
If buildVersionToDownload is selected as latest. Then the latest build id is retrieved via code. See code example here
So that in your custom task. When the Default Version is latest. You can get the latest build id in your code methods. And when Default Version is not latest. Then make the Artifact visible to select a build id from the picklist.