Azure ARM Template user defined function - azure

Question

I need to create 8 database and couple of collections though ARM template.I was going through the user defined function here https://learn.microsoft.com/en-us/azure/azure-resource-manager/templates/template-user-defined-functions to make the template simpler, Is that something I can achieve instead of copy paste the same scripts? right now, its throwing an error
Template validation failed: Unexpected initial token 'String' when
populating object.
My current Function:
"functions": [
{
"namespace": "contoso",
"members": {
"uniqueName": {
"parameters": [
{
"name": "databaseName",
"type": "string"
}
],
"output": {
"type": "object",
"value": {
"type": "Microsoft.DocumentDB/databaseAccounts/mongodbDatabases",
"name": "['test', '/', parameters('databaseName'))]",
"apiVersion": "2020-04-01",
"dependsOn": [ "[resourceId('Microsoft.DocumentDB/databaseAccounts/', 'test')]" ],
"properties": {
"resource": {
"id": "[parameters('databaseName')]"
}
}
}
}
}
}
}
],
Is that something we can achieve?
Update: Here is the simplified version
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"accountName": {
"type": "string",
"defaultValue": "test",
"metadata": {
"description": "Cosmos DB account name"
}
},
"databaseName": {
"type": "string",
"metadata": {
"description": "Cosmos DB database name"
}
}
},
"functions": [
{
"namespace": "contoso",
"members": {
"uniqueName": {
"parameters": [
{
"name": "databaseName",
"type": "string"
}
],
"output": {
"type": "object",
"value": {
"type": "Microsoft.DocumentDB/databaseAccounts/mongodbDatabases",
"name": "[concat('/test', '/', parameters('databaseName'))]",
"apiVersion": "2020-04-01",
"dependsOn": [ "[resourceId('Microsoft.DocumentDB/databaseAccounts/', 'test')]" ],
"properties": {
"resource": {
"id": "[parameters('databaseName')]"
}
}
}
}
}
}
}
],
"resources": [
{
"type": "Microsoft.DocumentDB/databaseAccounts",
"name": "[parameters('accountName')]",
"apiVersion": "2020-04-01",
"location": "central us",
"kind": "MongoDB",
"properties": {
"isVirtualNetworkFilterEnabled": false,
"databaseAccountOfferType": "Standard",
"apiProperties": {
"serverVersion": "3.6"
}
}
},
"[contoso.uniqueName(parameters('databaseName'))]"
]
}

Answer 1

Looks like you're trying to create several mongodbDatabases within the databaseAccounts resource.
I recommend looking at the ARM copy element.
https://learn.microsoft.com/en-us/azure/azure-resource-manager/templates/copy-resources#resource-iteration
It would look roughly like:
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"accountName": {
"type": "string",
"defaultValue": "test",
"metadata": {
"description": "Cosmos DB account name"
}
},
"databaseNames": {
"type": "array",
"defaultValue": [
"contoso",
"fabrikam",
"coho"
],
"metadata": {
"description": "Cosmos DB database names array"
}
}
},
"resources": [
{
"type": "Microsoft.DocumentDB/databaseAccounts",
"name": "[parameters('accountName')]",
"apiVersion": "2020-04-01",
"location": "central us",
"kind": "MongoDB",
"properties": {
"isVirtualNetworkFilterEnabled": false,
"databaseAccountOfferType": "Standard",
"apiProperties": {
"serverVersion": "3.6"
}
}
},
{
"type": "Microsoft.DocumentDB/databaseAccounts/mongodbDatabases",
"name": "[concat('/test', '/', parameters('databaseNames')[copyIndex()])]",
"apiVersion": "2020-04-01",
"dependsOn": [ "[resourceId('Microsoft.DocumentDB/databaseAccounts/', 'test')]" ],
"properties": {
"resource": {
"id": "[parameters('databaseNames')[copyIndex()]]"
}
},
"copy": {
"name": "databaseCopy",
"count": "[length(parameters('databaseNames'))]"
}
}
]
}