Perform Conditional Operations on Parameters in Azure ARM templates

README.md

Perform Conditional Operations on Parameters in Azure ARM templates

Let's say you have a need to perform a set of 4 contitional operations on an array passed in as a parameter to an ARM template. For example, let's say you need to pass in a name and a value and perform either no operation or add/subtract/multiply by 2. This gist contains an example deployment JSON, template JSON, and an expande version of the ARM logic. The value will 9999 if none of the supported operations are provided.

ARM-Logic.txt

[
    if(
        equals(
            parameters('settings')[copyIndex('settings')].type,
            'static'
        ),
        parameters('settings')[copyIndex('settings')].value,
        if(
            equals(
                parameters('settings')[copyIndex('settings')].type,
                'add'
            ),
            add(
                parameters('settings')[copyIndex('settings')].value,
                2
            ),
            if(
                equals(
                    parameters('settings')[copyIndex('settings')].type,
                    'mul'
                ),
                mul(
                    parameters('settings')[copyIndex('settings')].value,
                    2
                ),
                if(
                    equals(
                        parameters('settings')[copyIndex('settings')].type,
                        'sub'
                    ),
                    sub(
                        parameters('settings')[copyIndex('settings')].value,
                        2
                    ),
                    9999
                )
            )
        )
    )
]

azuredeploy.json

{
  "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "settings": {
      "type": "array"
    }
  },
  "variables": {
    "copy": [
      {
        "name": "settings",
        "count": "[length(parameters('settings'))]",
        "input": {
          "name": "[parameters('settings')[copyIndex('settings')].name]",
          "value": "[if(equals(parameters('settings')[copyIndex('settings')].type,'static'),parameters('settings')[copyIndex('settings')].value,if(equals(parameters('settings')[copyIndex('settings')].type,'add'),add(parameters('settings')[copyIndex('settings')].value,2),if(equals(parameters('settings')[copyIndex('settings')].type,'mul'),mul(parameters('settings')[copyIndex('settings')].value,2),if(equals(parameters('settings')[copyIndex('settings')].type,'sub'),sub(parameters('settings')[copyIndex('settings')].value,2),9999))))]"
        }
      }
    ]
  },
  "resources": [],
  "outputs": {
    "results": {
      "type": "array",
      "value": "[variables('settings')]"
    }
  }
}

azuredeploy.parameters.json

{
  "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "settings": {
      "value": [
        {
          "name": "a",
          "value": 1,
          "type": "static"
        },
        {
          "name": "b",
          "value": 2,
          "type": "add"
        },
        {
          "name": "c",
          "value": 3,
          "type": "mul"
        },
        {
          "name": "d",
          "value": 4,
          "type": "sub"
        }
      ]
    }
  }
}