Add support for empty input lists (#68)

* Add `FailOnEmpty` option to input

* Add fail on empty option to error condition

* Initialise empty results slice

With this change, if no groups are queried, an empty list is returned instead of null.

Signed-off-by: Tom van Dinther <[email protected]>

* Add empty cases for ref resolution tests

Also updates the mock to contain the same logic as added in the real implementation.

Signed-off-by: Tom van Dinther <[email protected]>

* Add test cases for `failOnEmpty` permutations

Signed-off-by: Tom van Dinther <[email protected]>

* Add FailOnEmpty option to function configuration options in README

Signed-off-by: Tom van Dinther <[email protected]>

---------

Signed-off-by: Tom van Dinther <[email protected]>
Co-authored-by: Yury Tsarev <[email protected]>

Author: tvandinther

README.md

@@ -275,7 +275,8 @@ spec:
 | `servicePrincipalsRef` | string | Reference to resolve a list of service principal names from `spec`, `status` or `context` (e.g., `spec.servicePrincipalConfig.names`) |
 | `target` | string | Required. Where to store the query results. Can be `status.<field>` or `context.<field>` |
 | `skipQueryWhenTargetHasData` | bool | Optional. When true, will skip the query if the target already has data |
-| `identity.type | string | Optional. Type of identity credentials to use. Valid values: `AzureServicePrincipalCredentials`, `AzureWorkloadIdentityCredentials`. Default is `AzureServicePrincipalCredentials` |
+| `FailOnEmpty` | bool | Optional. When true, the function will fail if the `users`, `groups`, or `servicePrincipals` lists are empty, or if their respective reference fields are empty lists. |
+| `identity.type` | string | Optional. Type of identity credentials to use. Valid values: `AzureServicePrincipalCredentials`, `AzureWorkloadIdentityCredentials`. Default is `AzureServicePrincipalCredentials` |
 
 ## Result Targets
 

fn.go

@@ -497,11 +497,11 @@ func (g *GraphQuery) graphQuery(ctx context.Context, azureCreds map[string]strin
 
 // validateUsers validates if the provided user principal names (emails) exist
 func (g *GraphQuery) validateUsers(ctx context.Context, client *msgraphsdk.GraphServiceClient, in *v1beta1.Input) (interface{}, error) {
-	if len(in.Users) == 0 {
+	if in.FailOnEmpty != nil && *in.FailOnEmpty && len(in.Users) == 0 {
 		return nil, errors.New("no users provided for validation")
 	}
 
-	var results []interface{}
+	results := make([]interface{}, 0)
 
 	for _, userPrincipalName := range in.Users {
 		if userPrincipalName == nil {
@@ -754,11 +754,11 @@ func (g *GraphQuery) getGroupMembers(ctx context.Context, client *msgraphsdk.Gra
 
 // getGroupObjectIDs retrieves object IDs for the specified group names
 func (g *GraphQuery) getGroupObjectIDs(ctx context.Context, client *msgraphsdk.GraphServiceClient, in *v1beta1.Input) (interface{}, error) {
-	if len(in.Groups) == 0 {
+	if in.FailOnEmpty != nil && *in.FailOnEmpty && len(in.Groups) == 0 {
 		return nil, errors.New("no group names provided")
 	}
 
-	var results []interface{}
+	results := make([]interface{}, 0)
 
 	for _, groupName := range in.Groups {
 		if groupName == nil {
@@ -799,11 +799,11 @@ func (g *GraphQuery) getGroupObjectIDs(ctx context.Context, client *msgraphsdk.G
 
 // getServicePrincipalDetails retrieves details about service principals by name
 func (g *GraphQuery) getServicePrincipalDetails(ctx context.Context, client *msgraphsdk.GraphServiceClient, in *v1beta1.Input) (interface{}, error) {
-	if len(in.ServicePrincipals) == 0 {
+	if in.FailOnEmpty != nil && *in.FailOnEmpty && len(in.ServicePrincipals) == 0 {
 		return nil, errors.New("no service principal names provided")
 	}
 
-	var results []interface{}
+	results := make([]interface{}, 0)
 
 	for _, spName := range in.ServicePrincipals {
 		if spName == nil {
@@ -1515,10 +1515,8 @@ func (f *Function) extractStringArrayFromMap(dataMap map[string]interface{}, fie
 				result = append(result, &strCopy)
 			}
 		}
-		if len(result) > 0 {
-			return result, nil
-		}
+		return result, nil
 	}
 
-	return nil, errors.Errorf("cannot resolve groupsRef: %s not a string array or empty", refKey)
+	return nil, errors.Errorf("cannot resolve groupsRef: %s not a string array", refKey)
 }