Retrieves all policy assignments that apply to a resource.

This operation retrieves the list of all policy assignments associated with the specified resource in the given resource group and subscription that match the optional given $filter. Valid values for $filter are: 'atScope()' or 'policyDefinitionId eq '{value}''. If $filter is not provided, the unfiltered list includes all policy assignments associated with the resource, including those that apply directly or from all containing scopes, as well as any applied to resources contained within the resource. If $filter=atScope() is provided, the returned list includes all policy assignments that apply to the resource, which is everything in the unfiltered list except those applied to resources contained within the resource. If $filter=policyDefinitionId eq '{value}' is provided, the returned list includes all policy assignments of the policy definition whose id is {value} that apply to the resource. Three parameters plus the resource name are used to identify a specific resource. If the resource is not part of a parent resource (the more common case), the parent resource path should not be provided (or provided as ''). For example a web app could be specified as ({resourceProviderNamespace} == 'Microsoft.Web', {parentResourcePath} == '', {resourceType} == 'sites', {resourceName} == 'MyWebApp'). If the resource is part of a parent resource, then all parameters should be provided. For example a virtual machine DNS name could be specified as ({resourceProviderNamespace} == 'Microsoft.Compute', {parentResourcePath} == 'virtualMachines/MyVirtualMachine', {resourceType} == 'domainNames', {resourceName} == 'MyComputerName'). A convenient alternative to providing the namespace and type name separately is to provide both in the {resourceType} parameter, format: ({resourceProviderNamespace} == '', {parentResourcePath} == '', {resourceType} == 'Microsoft.Web/sites', {resourceName} == 'MyWebApp').