Bicep accessor operators

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The accessor operators are used to access child resources, properties on objects, and elements in an array. You can also use the property accessor to use some functions.

Operator Name
[] Index accessor
. Function accessor
:: Nested resource accessor
. Property accessor

Index accessor

array[integerIndex]

object['stringIndex']

Use the index accessor to get either an element from an array or a property from an object.

For an array, provide the index as an integer. The integer matches the zero-based position of the element to retrieve.

For an object, provide the index as a string. The string matches the name of the object to retrieve.

The following example gets an element in an array.

var arrayVar = [
  'Coho'
  'Contoso'
  'Fabrikan'
]

output accessorResult string = arrayVar[1]

Output from the example:

Name Type Value
accessorResult string 'Contoso'

The next example gets a property on an object.

var environmentSettings = {
  dev: {
    name: 'Development'
  }
  prod: {
    name: 'Production'
  }
}

output accessorResult string = environmentSettings['dev'].name

Output from the example:

Name Type Value
accessorResult string 'Development'

Function accessor

resourceName.functionName()

Two functions - getSecret and list* - support the accessor operator for calling the function. These two functions are the only functions that support the accessor operator.

Example

The following example references an existing key vault, then uses getSecret to pass a secret to a module.

resource kv 'Microsoft.KeyVault/vaults@2019-09-01' existing = {
  name: kvName
  scope: resourceGroup(subscriptionId, kvResourceGroup )
}

module sql './sql.bicep' = {
  name: 'deploySQL'
  params: {
    sqlServerName: sqlServerName
    adminLogin: adminLogin
    adminPassword: kv.getSecret('vmAdminPassword')
  }
}

Nested resource accessor

parentResource::nestedResource

A nested resource is a resource that is declared within another resource. Use the nested resource accessor :: to access that nested resources from outside of the parent resource.

Within the parent resource, you reference the nested resource with just the symbolic name. You only need to use the nested resource accessor when referencing the nested resource from outside of the parent resource.

Example

The following example shows how to reference a nested resource from within the parent resource and from outside of the parent resource.

resource demoParent 'demo.Rp/parentType@2020-01-01' = {
  name: 'demoParent'
  location: 'China North'

  // Declare a nested resource within 'demoParent'
  resource demoNested 'childType' = {
    name: 'demoNested'
    properties: {
      displayName: 'The nested instance.'
    }
  }

  // Declare another nested resource
  resource demoSibling 'childType' = {
    name: 'demoSibling'
    properties: {
      // Use symbolic name to reference because this line is within demoParent
      displayName: 'Sibling of ${demoNested.properties.displayName}'
    }
  }
}

// Use nested accessor to reference because this line is outside of demoParent
output displayName string = demoParent::demoNested.properties.displayName

Property accessor

objectName.propertyName

Use property accessors to access properties of an object. Property accessors can be used with any object, including parameters and variables that are objects. You get an error when you use the property access on an expression that isn't an object.

Example

The following example shows an object variable and how to access the properties.

var x = {
  y: {
    z: 'Hello'
    a: true
  }
  q: 42
}

output outputZ string = x.y.z
output outputQ int = x.q

Output from the example:

Name Type Value
outputZ string 'Hello'
outputQ integer 42

Typically, you use the property accessor with a resource deployed in the Bicep file. The following example creates a public IP address and uses property accessors to return a value from the deployed resource.

resource publicIp 'Microsoft.Network/publicIPAddresses@2020-06-01' = {
  name: publicIpResourceName
  location: location
  properties: {
    publicIPAllocationMethod: dynamicAllocation ? 'Dynamic' : 'Static'
    dnsSettings: {
      domainNameLabel: publicIpDnsLabel
    }
  }
}

// Use property accessor to get value
output ipFqdn string = publicIp.properties.dnsSettings.fqdn

Next steps