ADO YAML pipeline - Passing object parameter to a template

Question

I've got a yaml pipeline calling a template:

parameters:
  - name: Food1
    type: string
  - name: Food2
    type: string
  - name: Food3
    type: string

jobs:
  - template: .\testLoop.yml
    parameters: 
      foodObject: |
        Food1: ${{ parameters.Food1 }}
        Food2: ${{ parameters.Food2 }}
        Food3: ${{ parameters.Food3 }}

The template's input parameter is of "object" type:

parameters:
  - name: foodObject
    type: object
    default:
    - Food1: 'Apple'
    - Food2: 'Bread'
    - Food3: 'Cheese'
jobs:
  - job: test_loop
    displayName: 'Test Loop'
    pool: 
      vmImage: windows-latest
    steps:
      - ${{ each food in parameters.foodObject }} :
        - powershell: |
            Write-Host "Food name is '${{ food.key }}' and value is '${{ food.value }}'"

However I get an error:

If the pipeline has an object parameter and I send that to the template, it works.

It seems like by "building" the object myself from string parameters, it never actually becomes a "mapping" (???) even though there are key value pairs separated by ":".

I've tried different formatting using " or ' or multiple lines or spaces and whatnot, and can't get this to work.

The error doesn't seem to refer to the input parameter, but rather to the "each" loop that is on line 9.

Any ideas how to fix this?

Answer 1

I can reproduce the same issue when using your YAML sample.

The cause of the issue can be that the format of the object parameters has issue when you pass to the template.

To solve this issue, you can use the following sample:

Main YAML:

parameters:
  - name: Food1
    type: string
  - name: Food2
    type: string
  - name: Food3
    type: string

jobs:
  - template: .\testLoop.yml
    parameters: 
      foodObject: 
      - name: food1
        value: ${{ parameters.Food1 }}
      - name: food2
        value: ${{ parameters.Food2 }}
      - name: food3
        value: ${{ parameters.Food3 }}

Template YAML:

parameters:
  - name: foodObject
    type: object
    default:
    - name: food1
      value: apple
    - name: food2
      value: Bread
    - name: food3
      value: Cheese
jobs:
  - job: test_loop
    displayName: 'Test Loop'
    pool: 
      vmImage: windows-latest
    steps:
      - ${{ each food in parameters.foodObject }} :
        - powershell: |
            Write-Host "Food name is '${{ food.name }}' and value is '${{ food.value }}'"

Result:

Update:

Here is another format of the YAML sample

Main:

parameters:
  - name: Food1
    type: string
  - name: Food2
    type: string
  - name: Food3
    type: string

jobs:
  - template: .\testLoop.yml
    parameters: 
      foodObject: 
        Food1: ${{ parameters.Food1 }}
        Food2: ${{ parameters.Food2 }}
        Food3: ${{ parameters.Food3 }}

Template:

parameters:
  - name: foodObject
    type: object
    default:
    - Food1: 'Apple'
    - Food2: 'Bread'
    - Food3: 'Cheese'
jobs:
  - job: test_loop
    displayName: 'Test Loop'
    pool: 
      vmImage: windows-latest
    steps:
      - ${{ each food in parameters.foodObject }} :
        - powershell: |
            Write-Host "Food name is '${{ food.key }}' and value is '${{ food.value }}'"