c# code gen doc

Signed-off-by: Clemens Vasters <clemens@vasters.com>

README.md

@@ -431,6 +431,7 @@ Parameters:
 - `--system-text-json-annotation`: (optional) If set, the tool will add System.Text.Json annotations to the C# classes.
 - `--newtonsoft-json-annotation`: (optional) If set, the tool will add Newtonsoft.Json annotations to the C# classes.
 - `--pascal-properties`: (optional) If set, the tool will use PascalCase properties in the C# classes.
+- `--namespace`: (optional) The namespace to use in the generated C# classes.
 
 Conversion notes:
 - The tool generates C# classes that represent the Avro schema as data classes.
@@ -439,10 +440,13 @@ Conversion notes:
   C# classes. Because the [`JSON Schema to Avro`](#convert-json-schema-to-avro-schema) conversion generally
   preserves the JSON Schema structure in the Avro schema, the generated C# classes
   can be used to serialize and deserialize data that is valid per the input JSON schema.
+- Only the `--system-text-json-annotation` option generates classes that support type unions.
 - The classes are generated into a directory structure that reflects the Avro namespace
   structure. The tool drops a minimal, default `.csproj` project file into the given
   directory if none exists.
 
+Read more about the C# code generation in the [C# code generation documentation](csharpcodegen.md).
+
 
 ### Generate Java code from Avro schema
 

avrotize/avrotize.py

@@ -82,6 +82,7 @@ def main():
     a2csharp_parser.add_argument('--system-text-json-annotation', action='store_true', help='Use System.Text.Json annotations', default=False)
     a2csharp_parser.add_argument('--newtonsoft-json-annotation', action='store_true', help='Use Newtonsoft.Json annotations', default=False)
     a2csharp_parser.add_argument('--pascal-properties', action='store_true', help='Use PascalCase properties', default=False)
+    a2csharp_parser.add_argument('--namespace', type=str, help='C# namespace', required=False)
 
     a2java_parser = subparsers.add_parser('a2java', help='Convert Avro schema to Java classes')
     a2java_parser.add_argument('--avsc', type=str, help='Path to the Avro schema file', required=True)
@@ -188,8 +189,9 @@ def main():
         system_text_json_annotation = args.system_text_json_annotation
         newtonsoft_json_annotation = args.newtonsoft_json_annotation
         pascal_properties = args.pascal_properties
+        namespace = args.namespace
         print(f'Converting Avro {avro_schema_path} to C# {csharp_path}')
-        convert_avro_to_csharp(avro_schema_path, csharp_path, avro_annotation=avro_annotation, system_text_json_annotation=system_text_json_annotation, newtonsoft_json_annotation=newtonsoft_json_annotation, pascal_properties=pascal_properties)
+        convert_avro_to_csharp(avro_schema_path, csharp_path, base_namespace=namespace, avro_annotation=avro_annotation, system_text_json_annotation=system_text_json_annotation, newtonsoft_json_annotation=newtonsoft_json_annotation, pascal_properties=pascal_properties)
     elif args.command == 'a2java':
         avro_schema_path = args.avsc
         java_path = args.java

avrotize/avrotocsharp.py

@@ -590,7 +590,8 @@ def generate_embedded_union(self, class_name: str, field_name: str, avro_type: L
             f"public partial class {class_name}\n{{\n" + \
             f"{INDENT}/// <summary>\n{INDENT}/// Union class for {field_name}\n{INDENT}/// </summary>\n"
         if self.system_text_json_annotation:
-            f"{INDENT}[System.Text.Json.Serialization.JsonConverter(typeof({union_class_name}))]\n"
+            class_definition += \
+                f"{INDENT}[System.Text.Json.Serialization.JsonConverter(typeof({union_class_name}))]\n"
         class_definition += \
             f"{INDENT}public sealed class {union_class_name}"
         if self.system_text_json_annotation: