How to get commit ID for a tag in Azure Devops git repository.

Question

I am trying to automate a view of all the workitems that have been closed between 2 branch tags of a git repo. One of the main issues I'm having is for some reason, when I view the tags from the tags page, I can see the commit id of the tags:

However, I can't for the life of me figure out how to get that commit id from a tag via REST API call.
I'm getting a list of the tags with the following:

$tagsUrl = "https://dev.azure.com/$Organization/$SystemTeamProject/_apis/git/repositories/$repositoryId/refs?filter=tags/&api-version=7.1-preview.1"
$tagsResponse = Invoke-RestMethod -Uri $tagsUrl -Method Get -Headers $headers
$allTags = $tagsResponse.value | ForEach-Object { $_.name -replace "refs/tags/", "" }

All the AI models retrieve it the same way, but it returns the "objectId" of that tag, which does not match the commit id!
https://dev.azure.com/{org}/{proj}/_apis/git/repositories/{repo/refs?filter=tags/24.2.1.601-RELEASE-CANDIDATE&api-version=7.1-preview.1

That does not match the commit id.

The initial tags are created via a PowerShell script once we create our release branch:

        git tag -a $releaseInfo.ReleaseTag -m "Tagging release branch"
        git push -q origin $releaseInfo.ReleaseTag

Answer 1

Hello Thomas Murnane,

To get the commit ID, use the /annotatedtags endpoint with the tag’s objectId. below is simple PowerShell script to do it:

$organization = "your-org"

$project = "your-project"

$repositoryId = "your-repo-id"

$pat = "your-personal-access-token"

$headers = @{ Authorization = "Basic " + [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(":$pat")) }

# Get the tags

$tagsUrl = "https://dev.azure.com/$organization/$project/_apis/git/repositories/$repositoryId/refs?filter=tags/&api-version=7.1-preview.1"

$tagsResponse = Invoke-RestMethod -Uri $tagsUrl -Method Get -Headers $headers

foreach ($tag in $tagsResponse.value) {

    $tagName = $tag.name -replace "refs/tags/", ""

    $tagObjectId = $tag.objectId

    # Get the commit ID

    $annotatedTagUrl = "https://dev.azure.com/$organization/$project/_apis/git/repositories/$repositoryId/annotatedtags/$tagObjectId?api-version=7.1-preview.1"

    $annotatedTagResponse = Invoke-RestMethod -Uri $annotatedTagUrl -Method Get -Headers $headers

    $commitId = $annotatedTagResponse.taggedObject.objectId

    Write-Output "Tag: $tagName, Commit ID: $commitId"

}

This will give you the commit ID (like 418392bc for 24.2.1.601-RELEASE-CANDIDATE) that matches the UI.

Hope this helps!

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Answer 2

I had this in my browser before I saw your answer, and I posted it. When the page refreshed, I saw your answer. I couldn't see a way to delete my post, but at least this shows another way.
I found that using the following API call, I was able to get the commit IDs from the results of this call:

function Get-CommitId {
    param (
        [string]$baseTag,
        [string]$targetTag
    )

    $uri = "https://dev.azure.com/$($Global:Organization)/$($Global:SystemTeamProject)/_apis/git/repositories/$($Global:repoName)/diffs/commits" +
        "?baseVersion=$baseTag" +
        "&baseVersionType=tag" +
        "&targetVersion=$targetTag" +
        "&targetVersionType=tag" +
        "&api-version=7.1"

    $response = Invoke-RestMethod -Uri $uri -Headers $Global:headers -Method Get

    return @{
        BaseCommit   = $response.baseCommit
        TargetCommit = $response.targetCommit
    }
}