Handle no child edge case

Author: marcelldls

pyproject.toml

@@ -17,6 +17,7 @@ dependencies = [
     "pvi~=0.10.0",
     "pytango",
     "softioc",
+    "strawberry-graphql[fastapi]",
 ]
 dynamic = ["version"]
 license.file = "LICENSE"
@@ -43,7 +44,6 @@ dev = [
     "types-mock",
     "aioca",
     "p4p",
-    "strawberry-graphql[fastapi]",
 ]
 
 [project.scripts]

src/fastcs/backends/graphQL/graphQL.py

@@ -99,6 +99,10 @@ def _dynamic_field():
     return strawberry.field(_dynamic_field)
 
 
+class NodeNotFoundError(Exception):
+    pass
+
+
 class FieldsTree:
     def __init__(self, name: str):
         self.name = name
@@ -108,28 +112,34 @@ def __init__(self, name: str):
             "mutation": [],
         }
 
-    def insert(self, path: list[str]):
+    def insert(self, path: list[str]) -> "FieldsTree":
         # Create child if not exist
         name = path.pop(0)
-        if not (child := self.get_child(name)):
+        if self.is_child(name):
+            child = self.get_child(name)
+        else:
             child = FieldsTree(name)
             self.children.append(child)
-        else:
-            child = self.get_child(name)
 
         # Recurse if needed
         if path:
             return child.insert(path)  # type: ignore
         else:
             return child
 
-    def get_child(self, name: str):
+    def is_child(self, name: str) -> bool:
+        for child in self.children:
+            if child.name == name:
+                return True
+        return False
+
+    def get_child(self, name: str) -> "FieldsTree":
         for child in self.children:
             if child.name == name:
                 return child
-        return None
+        raise NodeNotFoundError
 
-    def create_type(self, strawberry_type: str):
+    def create_type(self, strawberry_type: str) -> type:
         for child in self.children:
             child_field = _wrap_as_field(
                 child.name,