Removed root $ref from GenerateSchemaForType (#1033)

* support $ref and $defs in JSON Schema

* update

* removed root $ref from JSON Schema

* Update json.go

* Update json_test.go

* Update jsonschema/json.go

Co-authored-by: Copilot <[email protected]>

* Update jsonschema/json.go

Co-authored-by: Copilot <[email protected]>

---------

Co-authored-by: Copilot <[email protected]>

Author: eiixy

jsonschema/json.go

@@ -77,6 +77,27 @@ func GenerateSchemaForType(v any) (*Definition, error) {
 	if err != nil {
 		return nil, err
 	}
+	// If the schema has a root $ref, resolve it by:
+	// 1. Extracting the key from the $ref.
+	// 2. Detaching the referenced definition from $defs.
+	// 3. Checking for self-references in the detached definition.
+	//    - If a self-reference is found, restore the original $defs structure.
+	// 4. Flattening the referenced definition into the root schema.
+	// 5. Clearing the $ref field in the root schema.
+	if def.Ref != "" {
+		origRef := def.Ref
+		key := strings.TrimPrefix(origRef, "#/$defs/")
+		if root, ok := defs[key]; ok {
+			delete(defs, key)
+			root.Defs = defs
+			if containsRef(root, origRef) {
+				root.Defs = nil
+				defs[key] = root
+			}
+			*def = root
+		}
+		def.Ref = ""
+	}
 	def.Defs = defs
 	return def, nil
 }
@@ -189,3 +210,26 @@ func reflectSchemaObject(t reflect.Type, defs map[string]Definition) (*Definitio
 	d.Properties = properties
 	return &d, nil
 }
+
+func containsRef(def Definition, targetRef string) bool {
+	if def.Ref == targetRef {
+		return true
+	}
+
+	for _, d := range def.Defs {
+		if containsRef(d, targetRef) {
+			return true
+		}
+	}
+
+	for _, prop := range def.Properties {
+		if containsRef(prop, targetRef) {
+			return true
+		}
+	}
+
+	if def.Items != nil && containsRef(*def.Items, targetRef) {
+		return true
+	}
+	return false
+}

jsonschema/json_test.go

@@ -182,6 +182,18 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 	}
 }
 
+type User struct {
+	ID     int      `json:"id,omitempty"`
+	Name   string   `json:"name,omitempty"`
+	Orders []*Order `json:"orders,omitempty"`
+}
+
+type Order struct {
+	ID     int     `json:"id,omitempty"`
+	Amount float64 `json:"amount,omitempty"`
+	Buyer  *User   `json:"buyer,omitempty"`
+}
+
 func TestStructToSchema(t *testing.T) {
 	type Tweet struct {
 		Text string `json:"text"`
@@ -194,6 +206,13 @@ func TestStructToSchema(t *testing.T) {
 		Tweets  []Tweet  `json:"tweets,omitempty"`
 	}
 
+	type MyStructuredResponse struct {
+		PascalCase string `json:"pascal_case" required:"true" description:"PascalCase"`
+		CamelCase  string `json:"camel_case" required:"true" description:"CamelCase"`
+		KebabCase  string `json:"kebab_case" required:"true" description:"KebabCase"`
+		SnakeCase  string `json:"snake_case" required:"true" description:"SnakeCase"`
+	}
+
 	tests := []struct {
 		name string
 		in   any
@@ -444,6 +463,161 @@ func TestStructToSchema(t *testing.T) {
       "additionalProperties" : false
     }
   }
+}`,
+		},
+		{
+			name: "Test Person",
+			in:   Person{},
+			want: `{
+  "type": "object",
+  "properties": {
+    "age": {
+      "type": "integer"
+    },
+    "friends": {
+      "type": "array",
+      "items": {
+        "$ref": "#/$defs/Person"
+      }
+    },
+    "name": {
+      "type": "string"
+    },
+    "tweets": {
+      "type": "array",
+      "items": {
+        "$ref": "#/$defs/Tweet"
+      }
+    }
+  },
+  "additionalProperties": false,
+  "$defs": {
+    "Person": {
+      "type": "object",
+      "properties": {
+        "age": {
+          "type": "integer"
+        },
+        "friends": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Person"
+          }
+        },
+        "name": {
+          "type": "string"
+        },
+        "tweets": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Tweet"
+          }
+        }
+      },
+      "additionalProperties": false
+    },
+    "Tweet": {
+      "type": "object",
+      "properties": {
+        "text": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "text"
+      ],
+      "additionalProperties": false
+    }
+  }
+}`,
+		},
+		{
+			name: "Test MyStructuredResponse",
+			in:   MyStructuredResponse{},
+			want: `{
+  "type": "object",
+  "properties": {
+    "camel_case": {
+      "type": "string",
+      "description": "CamelCase"
+    },
+    "kebab_case": {
+      "type": "string",
+      "description": "KebabCase"
+    },
+    "pascal_case": {
+      "type": "string",
+      "description": "PascalCase"
+    },
+    "snake_case": {
+      "type": "string",
+      "description": "SnakeCase"
+    }
+  },
+  "required": [
+    "pascal_case",
+    "camel_case",
+    "kebab_case",
+    "snake_case"
+  ],
+  "additionalProperties": false
+}`,
+		},
+		{
+			name: "Test User",
+			in:   User{},
+			want: `{
+  "type": "object",
+  "properties": {
+    "id": {
+      "type": "integer"
+    },
+    "name": {
+      "type": "string"
+    },
+    "orders": {
+      "type": "array",
+      "items": {
+        "$ref": "#/$defs/Order"
+      }
+    }
+  },
+  "additionalProperties": false,
+  "$defs": {
+    "Order": {
+      "type": "object",
+      "properties": {
+        "amount": {
+          "type": "number"
+        },
+        "buyer": {
+          "$ref": "#/$defs/User"
+        },
+        "id": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false
+    },
+    "User": {
+      "type": "object",
+      "properties": {
+        "id": {
+          "type": "integer"
+        },
+        "name": {
+          "type": "string"
+        },
+        "orders": {
+          "type": "array",
+          "items": {
+            "$ref": "#/$defs/Order"
+          }
+        }
+      },
+      "additionalProperties": false
+    }
+  }
 }`,
 		},
 	}