[csharp][generichost] Remove discriminator property (OpenAPITools#18445)

* fixed nullability

* minor refactor to address a comment

* removed discriminator property

* update more manual tests

* update more manual tests

* added tests and bug fixes

* fixed allof

* reworked manual tests to compare json instead of classes, reworked discriminator logic

* removed unneeded code

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -589,10 +589,21 @@ public Map<String, ModelsMap> postProcessAllModels(Map<String, ModelsMap> objs)
         return objs;
     }
 
+    /**
+     * A property is new if it is in a derived class and the derived property is different.
+     * This usually occurs when the data type is different.
+     * We can also consider discriminators as new because the derived class discriminator will have to be defined again
+     * to contain a new value. Doing so prevents having to include the discriminator in the constructor.
+     * @param model
+     * @param property
+     * @return
+     */
     private boolean codegenPropertyIsNew(CodegenModel model, CodegenProperty property) {
         return model.parentModel == null
                 ? false
-                : model.parentModel.allVars.stream().anyMatch(p -> p.name.equals(property.name) && (p.dataType.equals(property.dataType) == false || p.datatypeWithEnum.equals(property.datatypeWithEnum) == false));
+                : model.parentModel.allVars.stream().anyMatch(p -> 
+                    p.name.equals(property.name) &&
+                    (p.dataType.equals(property.dataType) == false || p.datatypeWithEnum.equals(property.datatypeWithEnum) == false || p.isDiscriminator));
     }
 
     /**

modules/openapi-generator/src/main/resources/csharp/libraries/generichost/ClientUtils.mustache

@@ -336,6 +336,43 @@ using System.Runtime.CompilerServices;
             return JsonRegex.IsMatch(mime) || mime.Equals("application/json-patch+json");
         }
 
+        /// <summary>
+        /// Get the discriminator
+        /// </summary>
+        /// <param name="utf8JsonReader"></param>
+        /// <param name="discriminator"></param>
+        /// <returns></returns>
+        /// <exception cref="JsonException"></exception>
+        public static string{{nrt?}} GetDiscriminator(Utf8JsonReader utf8JsonReader, string discriminator)
+        {
+            int currentDepth = utf8JsonReader.CurrentDepth;
+
+            if (utf8JsonReader.TokenType != JsonTokenType.StartObject && utf8JsonReader.TokenType != JsonTokenType.StartArray)
+                throw new JsonException();
+
+            JsonTokenType startingTokenType = utf8JsonReader.TokenType;
+
+            while (utf8JsonReader.Read())
+            {
+                if (startingTokenType == JsonTokenType.StartObject && utf8JsonReader.TokenType == JsonTokenType.EndObject && currentDepth == utf8JsonReader.CurrentDepth)
+                    break;
+
+                if (startingTokenType == JsonTokenType.StartArray && utf8JsonReader.TokenType == JsonTokenType.EndArray && currentDepth == utf8JsonReader.CurrentDepth)
+                    break;
+
+                if (utf8JsonReader.TokenType == JsonTokenType.PropertyName && currentDepth == utf8JsonReader.CurrentDepth - 1)
+                {
+                    string{{nrt?}} localVarJsonPropertyName = utf8JsonReader.GetString();
+                    utf8JsonReader.Read();
+
+                    if (localVarJsonPropertyName != null && localVarJsonPropertyName.Equals(discriminator))
+                        return utf8JsonReader.GetString();
+                }
+            }
+
+            throw new JsonException("The specified discriminator was not found.");
+        }
+
         /// <summary>
         /// The base path of the API
         /// </summary>

modules/openapi-generator/src/main/resources/csharp/libraries/generichost/JsonConverter.mustache

@@ -44,6 +44,17 @@
 
             {{/-last}}
             {{/allVars}}
+            {{#discriminator}}
+            {{#children}}
+            {{#-first}}
+            string{{nrt?}} discriminator = ClientUtils.GetDiscriminator(utf8JsonReader, "{{discriminator.propertyBaseName}}");
+
+            {{/-first}}
+            if (discriminator != null && discriminator.Equals("{{name}}"))
+                return JsonSerializer.Deserialize<{{{name}}}>(ref utf8JsonReader, jsonSerializerOptions) ?? throw new JsonException("The result was an unexpected value.");
+
+            {{/children}}
+            {{/discriminator}}
             {{#model.discriminator}}
             {{#model.hasDiscriminatorWithNonEmptyMapping}}
             {{#mappedModels}}
@@ -281,7 +292,7 @@
             {{#model.hasDiscriminatorWithNonEmptyMapping}}
             {{#mappedModels}}
             if ({{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}} != null)
-                return new {{classname}}({{#lambda.joinWithComma}}{{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}{{^isNullable}}.Value{{/isNullable}}{{/vendorExtensions.x-is-value-type}}  {{#model.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}{{^isNullable}}.Value{{/isNullable}}{{/vendorExtensions.x-is-value-type}}  {{/model.composedSchemas.anyOf}}{{#allVars}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#required}}.Value{{nrt!}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}.Value{{/vendorExtensions.x-is-value-type}}{{/isNullable}}{{/required}}  {{/allVars}}{{/lambda.joinWithComma}});
+                return new {{classname}}({{#lambda.joinWithComma}}{{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}{{^isNullable}}.Value{{/isNullable}}{{/vendorExtensions.x-is-value-type}}  {{#model.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}{{^isNullable}}.Value{{/isNullable}}{{/vendorExtensions.x-is-value-type}}  {{/model.composedSchemas.anyOf}}{{#allVars}}{{^isDiscriminator}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#required}}.Value{{nrt!}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}.Value{{/vendorExtensions.x-is-value-type}}{{/isNullable}}{{/required}}  {{/isDiscriminator}}{{/allVars}}{{/lambda.joinWithComma}});
 
             {{#-last}}
             throw new JsonException();
@@ -300,14 +311,14 @@
 
             {{/-last}}
             {{/required}}
-            return new {{classname}}({{#lambda.joinWithComma}}{{#model.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}ParsedValue{{#required}}.Value{{#vendorExtensions.x-is-value-type}}{{nrt!}}.Value{{nrt!}}{{/vendorExtensions.x-is-value-type}}{{/required}}  {{/model.composedSchemas.anyOf}}{{#allVars}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#required}}.Value{{nrt!}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}.Value{{nrt!}}{{/vendorExtensions.x-is-value-type}}{{/isNullable}}{{/required}}  {{/allVars}}{{/lambda.joinWithComma}});
+            return new {{classname}}({{#lambda.joinWithComma}}{{#model.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}ParsedValue{{#required}}.Value{{#vendorExtensions.x-is-value-type}}{{nrt!}}.Value{{nrt!}}{{/vendorExtensions.x-is-value-type}}{{/required}}  {{/model.composedSchemas.anyOf}}{{#allVars}}{{^isDiscriminator}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#required}}.Value{{nrt!}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}.Value{{nrt!}}{{/vendorExtensions.x-is-value-type}}{{/isNullable}}{{/required}}  {{/isDiscriminator}}{{/allVars}}{{/lambda.joinWithComma}});
             {{/composedSchemas.oneOf}}
             {{^model.discriminator}}
             {{#composedSchemas}}
             {{#oneOf}}
             {{^vendorExtensions.x-duplicated-data-type}}
             if ({{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}} != null)
-                return new {{classname}}({{#lambda.joinWithComma}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}.Value{{/vendorExtensions.x-is-value-type}}  {{#model.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}{{^isNullable}}.Value{{/isNullable}}{{/vendorExtensions.x-is-value-type}}  {{/model.composedSchemas.anyOf}}{{#allVars}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#required}}ParsedValue{{/required}}  {{/allVars}}{{/lambda.joinWithComma}});
+                return new {{classname}}({{#lambda.joinWithComma}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}.Value{{/vendorExtensions.x-is-value-type}}  {{#model.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#vendorExtensions.x-is-value-type}}{{^isNullable}}.Value{{/isNullable}}{{/vendorExtensions.x-is-value-type}}  {{/model.composedSchemas.anyOf}}{{#allVars}}{{^isDiscriminator}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{#required}}ParsedValue{{/required}}  {{/isDiscriminator}}{{/allVars}}{{/lambda.joinWithComma}});
 
             {{/vendorExtensions.x-duplicated-data-type}}
             {{#-last}}
@@ -331,6 +342,18 @@
         public override void Write(Utf8JsonWriter writer, {{classname}} {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}, JsonSerializerOptions jsonSerializerOptions)
         {
             {{#lambda.trimLineBreaks}}
+            {{#lambda.copy}}
+            {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}
+            {{/lambda.copy}}
+            {{#discriminator}}
+            {{#children}}
+            if ({{#lambda.pasteLine}}{{/lambda.pasteLine}} is {{classname}} {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}){
+                JsonSerializer.Serialize<{{{name}}}>(writer, {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}, jsonSerializerOptions);
+                return;
+            }
+
+            {{/children}}
+            {{/discriminator}}
             writer.WriteStartObject();
 
             {{#model.discriminator}}
@@ -339,7 +362,7 @@
             {{^vendorExtensions.x-duplicated-data-type}}
             if ({{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}} != null) {
                 {{baseType}}JsonConverter {{#lambda.camelcase_sanitize_param}}{{baseType}}JsonConverter{{/lambda.camelcase_sanitize_param}} = ({{baseType}}JsonConverter) jsonSerializerOptions.Converters.First(c => c.CanConvert({{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}.GetType()));
-                {{#lambda.camelcase_sanitize_param}}{{baseType}}JsonConverter{{/lambda.camelcase_sanitize_param}}.WriteProperties(ref writer, {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}, jsonSerializerOptions);
+                {{#lambda.camelcase_sanitize_param}}{{baseType}}JsonConverter{{/lambda.camelcase_sanitize_param}}.WriteProperties(writer, {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}, jsonSerializerOptions);
             }
 
             {{/vendorExtensions.x-duplicated-data-type}}
@@ -352,13 +375,13 @@
             if ({{#lambda.joinWithAmpersand}}{{^required}}{{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}Option.IsSet  {{/required}}{{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}{{^required}}Option.Value{{/required}} != null{{/lambda.joinWithAmpersand}})
             {
                 {{datatypeWithEnum}}JsonConverter {{datatypeWithEnum}}JsonConverter = ({{datatypeWithEnum}}JsonConverter) jsonSerializerOptions.Converters.First(c => c.CanConvert({{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}{{^required}}Option.Value{{/required}}.GetType()));
-                {{datatypeWithEnum}}JsonConverter.WriteProperties(ref writer, {{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}{{^required}}Option.Value{{/required}}, jsonSerializerOptions);
+                {{datatypeWithEnum}}JsonConverter.WriteProperties(writer, {{#lambda.camelcase_sanitize_param}}{{model.classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}{{^required}}Option.Value{{/required}}, jsonSerializerOptions);
             }
 
             {{/anyOf}}
             {{/composedSchemas}}
             {{/model.discriminator}}
-            WriteProperties(ref writer, {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}, jsonSerializerOptions);
+            WriteProperties(writer, {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}, jsonSerializerOptions);
             writer.WriteEndObject();
             {{/lambda.trimLineBreaks}}
         }
@@ -370,20 +393,31 @@
         /// <param name="{{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}"></param>
         /// <param name="jsonSerializerOptions"></param>
         /// <exception cref="NotImplementedException"></exception>
-        public void WriteProperties(ref Utf8JsonWriter writer, {{classname}} {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}, JsonSerializerOptions jsonSerializerOptions)
+        public void WriteProperties(Utf8JsonWriter writer, {{classname}} {{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}, JsonSerializerOptions jsonSerializerOptions)
         {
             {{#lambda.trimTrailingWithNewLine}}
             {{#lambda.trimLineBreaks}}
             {{#allVars}}
+            {{^isDiscriminator}}
             {{^isNullable}}
             {{#vendorExtensions.x-is-reference-type}}
             if ({{^required}}{{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}Option.IsSet && {{/required}}{{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}} == null)
                 throw new ArgumentNullException(nameof({{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}), "Property is required for class {{classname}}.");
 
             {{/vendorExtensions.x-is-reference-type}}
             {{/isNullable}}
+            {{/isDiscriminator}}
             {{/allVars}}
             {{#allVars}}
+            {{#isDiscriminator}}
+            {{^model.composedSchemas.anyOf}}
+            {{^model.composedSchemas.oneOf}}
+            writer.WriteString("{{baseName}}", {{^isEnum}}{{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}{{/isEnum}}{{#isNew}}{{#isEnum}}{{#isInnerEnum}}{{classname}}.{{{datatypeWithEnum}}}ToJsonValue{{/isInnerEnum}}{{^isInnerEnum}}{{{datatypeWithEnum}}}ValueConverter.ToJsonValue{{/isInnerEnum}}({{#lambda.camelcase_sanitize_param}}{{classname}}{{/lambda.camelcase_sanitize_param}}.{{name}}{{^required}}.Value{{/required}}){{/isEnum}}{{/isNew}});
+
+            {{/model.composedSchemas.oneOf}}
+            {{/model.composedSchemas.anyOf}}
+            {{/isDiscriminator}}
+            {{^isDiscriminator}}
             {{#isString}}
             {{^isMap}}
             {{^isEnum}}
@@ -579,6 +613,7 @@
             {{/isString}}
             {{/isEnum}}
             {{/isUuid}}
+            {{/isDiscriminator}}
             {{/allVars}}
             {{/lambda.trimLineBreaks}}
             {{/lambda.trimTrailingWithNewLine}}

modules/openapi-generator/src/main/resources/csharp/libraries/generichost/ModelBaseSignature.mustache

@@ -1 +1 @@
-{{#parentModel.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{parent}}{{/lambda.camelcase_sanitize_param}}.{{#lambda.titlecase}}{{baseType}}{{#isArray}}{{{dataFormat}}}{{/isArray}}{{/lambda.titlecase}}  {{/parentModel.composedSchemas.anyOf}}{{#allVars}}{{#isInherited}}{{^isNew}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{/isNew}}{{#isNew}}{{#isEnum}}{{#isInnerEnum}}{{classname}}.{{{datatypeWithEnum}}}ToJsonValue{{/isInnerEnum}}{{^isInnerEnum}}{{{datatypeWithEnum}}}ValueConverter.ToJsonValue{{/isInnerEnum}}({{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{^required}}.Value{{/required}}){{/isEnum}}{{^isEnum}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}.ToString(){{/isEnum}}{{/isNew}}  {{/isInherited}}{{/allVars}}
+{{#parentModel.composedSchemas.anyOf}}{{#lambda.camelcase_sanitize_param}}{{parent}}{{/lambda.camelcase_sanitize_param}}.{{#lambda.titlecase}}{{baseType}}{{#isArray}}{{{dataFormat}}}{{/isArray}}{{/lambda.titlecase}}  {{/parentModel.composedSchemas.anyOf}}{{#allVars}}{{^isDiscriminator}}{{#isInherited}}{{^isNew}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{/isNew}}{{#isNew}}{{#isEnum}}{{#isInnerEnum}}{{classname}}.{{{datatypeWithEnum}}}ToJsonValue{{/isInnerEnum}}{{^isInnerEnum}}{{{datatypeWithEnum}}}ValueConverter.ToJsonValue{{/isInnerEnum}}({{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}{{^required}}.Value{{/required}}){{/isEnum}}{{^isEnum}}{{#lambda.camelcase_sanitize_param}}{{name}}{{/lambda.camelcase_sanitize_param}}.ToString(){{/isEnum}}{{/isNew}}  {{/isInherited}}{{/isDiscriminator}}{{/allVars}}

modules/openapi-generator/src/main/resources/csharp/libraries/generichost/ModelSignature.mustache

@@ -1 +1 @@
-{{#model.allVars}}{{^required}}Option<{{/required}}{{{datatypeWithEnum}}}{{>NullConditionalProperty}}{{^required}}>{{/required}} {{#lambda.escape_reserved_word}}{{#lambda.camel_case}}{{name}}{{/lambda.camel_case}}{{/lambda.escape_reserved_word}}{{#defaultValue}} = {{^required}}default{{/required}}{{#required}}{{^isDateTime}}{{#isString}}{{^isEnum}}@{{/isEnum}}{{/isString}}{{{.}}}{{/isDateTime}}{{#isDateTime}}default{{/isDateTime}}{{/required}}{{/defaultValue}}{{^defaultValue}}{{#lambda.first}}{{#isNullable}} = default  {{/isNullable}}{{^required}} = default  {{/required}}{{/lambda.first}}{{/defaultValue}}  {{/model.allVars}}
+{{#model.allVars}}{{^isDiscriminator}}{{^required}}Option<{{/required}}{{{datatypeWithEnum}}}{{>NullConditionalProperty}}{{^required}}>{{/required}} {{#lambda.escape_reserved_word}}{{#lambda.camel_case}}{{name}}{{/lambda.camel_case}}{{/lambda.escape_reserved_word}}{{#defaultValue}} = {{^required}}default{{/required}}{{#required}}{{^isDateTime}}{{#isString}}{{^isEnum}}@{{/isEnum}}{{/isString}}{{{.}}}{{/isDateTime}}{{#isDateTime}}default{{/isDateTime}}{{/required}}{{/defaultValue}}{{^defaultValue}}{{#lambda.first}}{{#isNullable}} = default  {{/isNullable}}{{^required}} = default  {{/required}}{{/lambda.first}}{{/defaultValue}}  {{/isDiscriminator}}{{/model.allVars}}