[BUG] Export-AzPolicyAssignmentRuleData unable to export Azure policy as PSRule (The function "field" was not found) [Custom policy: DDoS Alert Rules For PublicIP]

### Existing rule

_No response_

### Description of the issue

Unable to export policy assignment data to PSRule.

```json
{
"Name": "00000000-0000-0000-0000-000000000000",
"ResourceId": "/providers/Microsoft.Management/managementGroups/MyManagementGroup/providers/Microsoft.Authorization/policyDefinitions/00000000-0000-0000-0000-000000000000",
"ResourceName": "00000000-0000-0000-0000-000000000000",
"ResourceType": "Microsoft.Authorization/policyDefinitions",
"SubscriptionId": null,
"Properties": {
"Description": "This policy deploys alert rules for Azure Public IP Addresses if not exist.",
"DisplayName": "DDoS Alert Rules For PublicIP",
"Metadata": {
"version": "0.0.1",
"category": "Monitoring",
"status": "Active",
"Control": "ABC1, ABC2, ABC3, ABC4, ABC5",
"purpose": "This policy deploys alert rules for Azure Public IP Addresses if not exist.",
"tags": [
{
"managedpolicy": "true"
}
],
"createdBy": "00000000-0000-0000-0000-000000000000",
"createdOn": "2023-06-14T14:15:52.8625112Z",
"updatedBy": null,
"updatedOn": null
},
"Mode": "Indexed",
"Parameters": {
"resourceTags": {
"type": "object",
"metadata": {
"displayName": "Alert Tags",
"description": "Tags to be added in alerts"
}
},
"alertDescription": {
"type": "String",
"metadata": {
"displayName": "Alert Description",
"description": "Description of alert"
},
"defaultValue": "DDOS"
},
"alertSeverity": {
"type": "String",
"metadata": {
"displayName": "Alert Severity",
"description": "Severity of alert {0,1,2,3,4}"
},
"allowedValues": [
"0",
"1",
"2",
"3",
"4"
],
"defaultValue": "0"
},
"metricName": {
"type": "String",
"metadata": {
"displayName": "Metric Name",
"description": "Name of the metric used in the comparison to activate the alert."
},
"defaultValue": "IfUnderDDoSAttack"
},
"operator": {
"type": "String",
"metadata": {
"displayName": "Operator",
"description": "Operator comparing the current value with the threshold value."
},
"allowedValues": [
"Equals",
"NotEquals",
"GreaterThan",
"GreaterThanOrEqual",
"LessThan",
"LessThanOrEqual"
],
"defaultValue": "GreaterThan"
},
"timeAggregation": {
"type": "String",
"metadata": {
"displayName": "timeAggregation",
"description": "How the data that is collected should be combined over time."
},
"allowedValues": [
"Average",
"Minimum",
"Maximum",
"Total",
"Count"
],
"defaultValue": "Maximum"
},
"evaluationFrequency": {
"type": "String",
"metadata": {
"displayName": "Evaluation Frequency",
"description": "how often the metric alert is evaluated represented in ISO 8601 duration format"
},
"allowedValues": [
"PT1M",
"PT5M",
"PT15M",
"PT30M",
"PT1H"
],
"defaultValue": "PT5M"
},
"windowSize": {
"type": "String",
"metadata": {
"displayName": "Window Size",
"description": "Period of time used to monitor alert activity based on the threshold. Must be between one minute and one day. ISO 8601 duration format."
},
"allowedValues": [
"PT1M",
"PT5M",
"PT15M",
"PT30M",
"PT1H",
"PT6H",
"PT12H",
"PT24H"
],
"defaultValue": "PT5M"
},
"actionGroupId": {
"type": "String",
"metadata": {
"displayName": "Action Group Id",
"description": "The ID of the action group that is triggered when the alert is activated or deactivated."
}
},
"targetResourceType": {
"type": "String",
"metadata": {
"displayName": "target Resource Type",
"description": "Specifies the target resource type. For example: Microsoft.Network/publicIPAddresses"
},
"defaultValue": "Microsoft.Network/publicIPAddresses"
}
},
"PolicyRule": {
"if": {
"field": "type",
"equals": "[parameters('targetResourceType')]"
},
"then": {
"effect": "deployIfNotExists",
"details": {
"type": "Microsoft.Insights/metricalerts",
"existenceCondition": {
"allOf": [
{
"field": "name",
"equals": "[concat('DDoSAlert','-', field('name'))]"
},
{
"field": "Microsoft.Insights/metricalerts/targetResourceType",
"equals": "[parameters('targetResourceType')]"
},
{
"field": "Microsoft.Insights/metricalerts/actions[*].actionGroupId",
"equals": "[parameters('actionGroupId')]"
},
{
"field": "Microsoft.Insights/metricalerts/enabled",
"equals": "true"
},
{
"field": "Microsoft.Insights/metricalerts/scopes[*]",
"equals": "[concat('/subscriptions/', subscription().subscriptionId, '/resourcegroups/', resourceGroup().name, '/providers/', parameters('targetResourceType'), '/', field('name'))]"
}
]
},
"roleDefinitionIds": [],
"deployment": {
"properties": {
"mode": "incremental",
"template": {
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"Name": {
"type": "string"
},
"targetResourceType": {
"type": "string"
},
"actionGroupId": {
"type": "string"
},
"alertDescription": {
"type": "string"
},
"alertSeverity": {
"type": "string"
},
"evaluationFrequency": {
"type": "string"
},
"windowSize": {
"type": "string"
},
"metricName": {
"type": "string"
},
"operator": {
"type": "string"
},
"timeAggregation": {
"type": "string"
},
"resourceTags": {
"type": "object"
}
},
"variables": {},
"resources": [
{
"name": "[concat('DDoSAlert','-',parameters('name'))]",
"type": "Microsoft.Insights/metricAlerts",
"location": "global",
"apiVersion": "2018-03-01",
"tags": "[parameters('resourceTags')]",
"properties": {
"description": "[parameters('alertDescription')]",
"severity": "[int(parameters('alertSeverity'))]",
"enabled": "true",
"scopes": [
"[concat('/subscriptions/', subscription().subscriptionId, '/resourcegroups/', resourceGroup().name, '/providers/', parameters('targetResourceType'), '/', parameters('name'))]"
],
"evaluationFrequency": "[parameters('evaluationFrequency')]",
"windowSize": "[parameters('windowSize')]",
"criteria": {
"odata.type": "Microsoft.Azure.Monitor.SingleResourceMultipleMetricCriteria",
"allOf": [
{
"name": "1st criteria",
"metricName": "[parameters('metricName')]",
"dimensions": [],
"operator": "[parameters('operator')]",
"threshold": 0,
"timeAggregation": "[parameters('timeAggregation')]"
}
]
},
"actions": [
{
"actionGroupId": "[parameters('actionGroupId')]"
}
]
}
}
]
},
"parameters": {
"name": {
"value": "[field('name')]"
},
"targetResourceType": {
"value": "[parameters('targetResourceType')]"
},
"actionGroupId": {
"value": "[parameters('actionGroupId')]"
},
"alertDescription": {
"value": "[parameters('alertDescription')]"
},
"alertSeverity": {
"value": "[parameters('alertSeverity')]"
},
"evaluationFrequency": {
"value": "[parameters('evaluationFrequency')]"
},
"windowSize": {
"value": "[parameters('windowSize')]"
},
"metricName": {
"value": "[parameters('metricName')]"
},
"operator": {
"value": "[parameters('operator')]"
},
"timeAggregation": {
"value": "[parameters('timeAggregation')]"
},
"resourceTags": {
"value": "[parameters('resourceTags')]"
}
}
}
}
}
}
},
"PolicyType": 1
},
"PolicyDefinitionId": "/providers/Microsoft.Management/managementGroups/MyManagementGroup/providers/Microsoft.Authorization/policyDefinitions/00000000-0000-0000-0000-000000000000"
}
```

### Error messages

An error occurred evaluating expression '[concat('DDoSAlert','-', field('name'))]' line 159. The function "field" was not found.

### Reproduction

Exporting policy assignment data

### Version of PSRule

2.9.0

### Version of PSRule for Azure

1.33.2

### Additional context

This bug is related to #1323