Compute changeset difference between two releases using API's

Below are the steps which can be followed to compute changeset difference between two releases for TFVC project 

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Step1: Get details of the primary build artifact for the current release  using build API. Store 'sourceVersion' say as 'currentReleaseBuildVersion'

https://{account}.visualstudio.com/{project}/_apis/build/builds/{buildId}

e.g. https://testking123.visualstudio.com/3a607d2a-d6c9-4274-9d13-d83c544d5063/_apis/build/builds/2348

Step2: Get details of the primary build artifact for the older release. Store 'sourceVersion' say as 'baseReleaseBuildVersion'

Step3: Make sure as build definition for both the builds in Step#1 and Step#2 are same

Step4: Get the build definition details for above builds using API to get 'tfvcMapping' for further filtering

https://{account}.visualstudio.com/{project}/_apis/build/Definitions/{definitionId}

e.g. https://testking123.visualstudio.com/3a607d2a-d6c9-4274-9d13-d83c544d5063/\_apis/build/Definitions/288

Step5: Make TFVC API to find the difference using API

https://{account}.visualstudio.com/{project}/_apis/tfvc/changesets?searchCriteria.fromId=<baseReleaseBuildVersion>&searchCriteria.toId=<currentReleaseBuildVersion>&searchCriteria.itemPath=<item path as got in step#3 to filter further>

e.g.

https://testking123.visualstudio.com/3a607d2a-d6c9-4274-9d13-d83c544d5063/_apis/tfvc/changesets?searchCriteria.fromId=282&searchCriteria.toId=284

Step6: Done!!!!

Below are the steps which can be followed to compute changeset difference between two releases for TFGIT project 

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Step1: Get details of the primary build artifact for the current release  using build API. Store 'sourceVersion' say as 'currentReleaseBuildVersion'

https://{account}.visualstudio.com/{project}/_apis/build/builds/{buildId}

e.g. https://testking123.visualstudio.com/3a607d2a-d6c9-4274-9d13-d83c544d5063/_apis/build/builds/2348

Step2: Get details of the primary build artifact for the older release. Store 'sourceVersion' say as 'baseReleaseBuildVersion'

Step3: Make sure as build definition and repositoryId for both the builds in Step#1 and Step#2 are same. Store ''repository.Id' say as repositoryId.

Step4: Make POST call using  TFGIT API to find the difference using API

https://{account}.visualstudio.com/{project}/_apis/git/repositories/{repository}/commitsBatch?api-version=1.0

Request body: {"itemVersion":{"versionType":"commit","version":"fromCommitGUIDHere"},"compareVersion":{"versionType":"commit","version":"toCommitGUIDHere"}}

e.g. https://testking123.visualstudio.com/3a607d2a-d6c9-4274-9d13-d83c544d5063/_apis/git/repositories/278d5cd2-584d-4b63-824a-2ba458937249/commitsBatch?api-version=1.0

Request body: {"itemVersion":{"versionType":"commit","version":"currentReleaseBuildVersion"},"compareVersion":{"versionType":"commit","version":"baseReleaseBuildVersion"}}

Step5: Done