azurerm_data_source - optimize api with resource_group_name (#21661)

internal/services/resource/resources_data_source.go

@@ -84,11 +84,6 @@ func dataSourceResourcesRead(d *pluginsdk.ResourceData, meta interface{}) error
 
 	var filter string
 
-	if resourceGroupName != "" {
-		v := fmt.Sprintf("resourceGroup eq '%s'", resourceGroupName)
-		filter += v
-	}
-
 	if resourceName != "" {
 		if strings.Contains(filter, "eq") {
 			filter += " and "
@@ -106,10 +101,20 @@ func dataSourceResourcesRead(d *pluginsdk.ResourceData, meta interface{}) error
 	}
 
 	// Use List instead of listComplete because of bug in SDK: https://github.com/Azure/azure-sdk-for-go/issues/9510
+	var resourcesResp resources.ListResultPage
 	resources := make([]map[string]interface{}, 0)
-	resourcesResp, err := client.List(ctx, filter, "", nil)
-	if err != nil {
-		return fmt.Errorf("getting resources: %+v", err)
+	if resourceGroupName != "" {
+		resp, err := client.ListByResourceGroup(ctx, resourceGroupName, filter, "", nil)
+		if err != nil {
+			return fmt.Errorf("getting resources by resource group: %+v", err)
+		}
+		resourcesResp = resp
+	} else {
+		resp, err := client.List(ctx, filter, "", nil)
+		if err != nil {
+			return fmt.Errorf("getting resources: %+v", err)
+		}
+		resourcesResp = resp
 	}
 
 	resources = append(resources, filterResource(resourcesResp.Values(), requiredTags)...)