Post Method - Changing a Nested Value - rest

Question

I am trying to change a value - specifically a variable - of one of my TFS 2017 builds. To my understanding, Patch is not supported at all. I can successfully queue a build with the Post method and I am trying to use the same command change a value as well.
When I run the Get method, I have:
*A bunch of text*
"variables": {
"system.debug": {
"value": "false",
"allowOverride": true
},
"BuildVersion": {
"value": "ValueIWantToChange"
}
},
*A bunch of text*
I need to change the Build Version and everything else will stay the same. My body in Postman looks like:
{
"Variables":
{
"BuildVersion":
{
"value": NewValue
}
}
}
When I run this in Postman, I get this error:
"Value cannot be null.\r\nParameter name: definition.Repository"
Could anyone tell me where I am going wrong or if this is possible using another method?

Answer 1

Seems you want to update the build definition base on you description.
To update the build definition with the REST API you need to use PUT method, please see Definitions - Update Definition for details.
Get the build definition first:
GET http://server:8080/tfs/DefaultCollection/ScrumProject/_apis/build/definitions/6?api-version=3.2
Copy all the json response from the first step as the request body,
then change the value of the specific variable which you want to be
modified.
PUT http://SERVER:8080/tfs/DefaultCollection/ScrumProject/_apis/build/definitions/6?api-version=3.2
Content-Type: application/json
Note that you need to provide the latest revision in request body:
UPDATE:
You can also use PowerShell by calling the REST API to update the specific variable value, just try below sample: (the variable name is lctest in below sample, you just need to replace it with your own variable name.)
Param(
[string]$collectionurl = "http://server:8080/tfs/DefaultCollection",
[string]$project = "ProjectName",
[string]$definitionid = "6",
[string]$user = "username",
[string]$token = "password"
)
# Base64-encodes the Personal Access Token (PAT) appropriately
$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $user,$token)))
#Get build definition
$defurl = "$collectionurl/$project/_apis/build/definitions/$($definitionid)?api-version=3.2"
$definition = Invoke-RestMethod -Uri $defurl -Method Get -UseDefaultCredential -Headers #{Authorization=("Basic {0}" -f $base64AuthInfo)}
#Set new value for the specific variable
$definition.variables.lctest.value = "1.0.0.4"
$json = #($definition) | ConvertTo-Json -Depth 99
#Update the definition
$updatedef = Invoke-RestMethod -Uri $defurl -Method Put -Body $json -ContentType "application/json" -Headers #{Authorization=("Basic {0}" -f $base64AuthInfo)}
write-host $definition.variables.lctest.value

Answer 2

I figured out my problem awhile back and forgot to update. My initial task was to get the API for octopus so this is the long version. If youre only interested in the REST commands, refer to the last section of code. Just wanted to add the rest in for extra context.
#Create a folder
if(test-Path C:\Test){}
else{
new-item -path "C:\" -name "Test" -ItemType "directory"}
$encodedPAT = [System.Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes(":$TFSAPIKeyForAutomatedBuild"))
$GetURI = "$MyURI"
$headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
$headers.Add("Authorization", "Basic $encodedPAT")
[string]$Global:ChangeVersion = [version]$OctopusParameters["Octopus.Action[Deploy Package].Package.NuGetPackageVersion"]
write-host $ChangeVersion
$GetBuildresponse = Invoke-RestMethod -Method Get -header $headers -ContentType "application/json" -Uri $GetUri
write-host $GetBuildResponse
$y = convertTo-json $GetBuildresponse -depth 99 | Out-file -FilePath "C:\test\FromPostmanCopy.json"
$z = (get-content "C:\test\FromPostmanCopy.json") | select-string -pattern '(?<=value": "2.)(.*)(?=")' | % { $_.Matches} | % { $_.value }
Write-Host $z
$Content = (Get-Content "C:\Test\FromPostmanCopy.json")
$content -replace "2.$z", $changeVersion | out-file "C:\Test\FromPostmanCopy.json"
$Content = (Get-Content "C:\Test\FromPostmanCopy.json")
$Buildresponse = Invoke-RestMethod -URI $GetURI -Method Put -header $headers -Body $content -ContentType application/json