How to get the value of parameter in condition azure pipelines yaml - azure-devops

Question

Here's a section of my YAML pipeline:
parameters:
- name: appEnv
default: None
type: string
values:
- None
- Dev
- QA
- Stage
- Stage2
- Prod
variables:
- name: envConfiguration
${{ if and(eq('${{parameters.appEnv}}', 'None'), startsWith(variables['Build.SourceBranchName'], 'release/')) }}:
value: Prod
${{ elseif and(eq('${{parameters.appEnv}}', 'None'), startsWith(variables['Build.SourceBranchName'], 'hotfix/')) }}:
value: Prod
${{ elseif and(eq('${{parameters.appEnv}}', 'None'), startsWith(variables['System.PullRequest.TargetBranch'], 'release/')) }}:
value: Stage
${{ elseif and(eq('${{parameters.appEnv}}', 'None'), startsWith(variables['System.PullRequest.TargetBranch'], 'hotfix/')) }}:
value: Stage2
${{ elseif eq('${{parameters.appEnv}}', 'None') }}:
value: Dev
${{ else }}:
value: ${{parameters.appEnv}}
- name: envFileName
${{ if eq(variables.envConfiguration, 'Dev') }}:
value: .env.dev
${{ if eq(variables.envConfiguration, 'QA') }}:
value: .env.qa
${{ if eq(variables.envConfiguration, 'Stage') }}:
value: .env.stage
${{ if eq(variables.envConfiguration, 'Stage2') }}:
value: .env.stage2
${{ if eq(variables.envConfiguration, 'Prod') }}:
value: .env.prod
The problem is that the envConfiguration conditions are never honoured. Whenever I create a PR targeting the release/ branch the value is always None. I think it is because of runtime and compile time variables (not sure).
All I want to do is select the correct .env file based on the appEnv parameter and the source and target branches.

Answer 1

You are using incorrect syntax.
${{ if and(eq('${{parameters.appEnv}}', 'None'), startsWith(variables['Build.SourceBranchName'], 'release/')) }}:
should be
${{ if and(eq(parameters.appEnv, 'None'), startsWith(variables['Build.SourceBranchName'], 'release/')) }}:
As written, it's doing a literal comparison of the values ${{parameters.appEnv}} and None, which will, of course, always be false.
In general, refer to the documentation for examples of correct syntax.