From c01585036af05bc96f7f24e89c9b72ce60e7d057 Mon Sep 17 00:00:00 2001
From: Koudai Aono <koxudaxi@gmail.com>
Date: Thu, 30 Sep 2021 23:27:51 +0900
Subject: [PATCH] Fix a bug for # field (#558)

---
 datamodel_code_generator/reference.py                          | 2 +-
 .../expected/main/main_jsonschema_special_field_name/output.py | 1 +
 tests/data/jsonschema/special_field_name.json                  | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/datamodel_code_generator/reference.py b/datamodel_code_generator/reference.py
index 95615dd27..8fe24d3f1 100644
--- a/datamodel_code_generator/reference.py
+++ b/datamodel_code_generator/reference.py
@@ -146,7 +146,7 @@ def get_valid_name(
         if not name:
             name = self.empty_field_name
         if name[0] == '#':
-            name = name[1:]
+            name = name[1:] or self.empty_field_name
         # TODO: when first character is a number
         name = re.sub(r'\W', '_', name)
         if name[0].isnumeric():
diff --git a/tests/data/expected/main/main_jsonschema_special_field_name/output.py b/tests/data/expected/main/main_jsonschema_special_field_name/output.py
index 8e9cb3482..93b41ff4f 100644
--- a/tests/data/expected/main/main_jsonschema_special_field_name/output.py
+++ b/tests/data/expected/main/main_jsonschema_special_field_name/output.py
@@ -15,3 +15,4 @@ class SpecialField(BaseModel):
     class_: Optional[int] = Field(None, alias='class')
     class_s: Optional[int] = Field(None, alias="class's")
     class_s_1: Optional[str] = Field(None, alias='class-s')
+    _: Optional[str] = Field(None, alias='#')
diff --git a/tests/data/jsonschema/special_field_name.json b/tests/data/jsonschema/special_field_name.json
index 1d959ba81..09e78d7b1 100644
--- a/tests/data/jsonschema/special_field_name.json
+++ b/tests/data/jsonschema/special_field_name.json
@@ -17,6 +17,9 @@
     },
     "class-s": {
       "type": "string"
+    },
+    "#": {
+      "type": "string"
     }
   }
 }
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