Add support for eager-loading nested relations

orm/src/model/ModelResultOperator.ts

@@ -29,9 +29,19 @@ export default class ModelResultOperator<T extends Model<T>> extends ResultOpera
             const eagers = query.eager_relations
             const model = new this.ModelClass()
 
-            for ( const rel_name of eagers ) {
+            for ( const full_rel_name of eagers ) {
+                const rel_name = full_rel_name.split('.')[0]
+                const child_eagers = eagers.filter((x: string) => x.startsWith(`${rel_name}.`)).map((x: string) => {
+                    return x.split('.').slice(1).join('.')
+                })
+
                 const relation = model.get_relation(rel_name)
                 const select = await relation.build_eager_query(query, results)
+
+                for ( const child_eager of child_eagers ) {
+                    select.with(child_eager)
+                }
+
                 const all_related = await select.results()
                 results.each(result => {
                     const result_relation = result.get_relation(rel_name)