feat: refine additional properties default values, to make them bette…

…r match their value type in generated code

pkg/generator/generate.go

@@ -833,7 +833,7 @@ func (g *schemaGenerator) generateStructType(
 
 		switch {
 		case prop.Default != nil:
-			structField.DefaultValue = prop.Default
+			structField.DefaultValue = g.defaultPropertyValue(prop)
 
 		default:
 			if isRequired {
@@ -849,6 +849,42 @@ func (g *schemaGenerator) generateStructType(
 	return &structType, nil
 }
 
+func (g *schemaGenerator) defaultPropertyValue(prop *schemas.Type) any {
+	if prop.AdditionalProperties != nil {
+		if len(prop.AdditionalProperties.Type) == 0 {
+			return map[string]any{}
+		}
+
+		if len(prop.AdditionalProperties.Type) != 1 {
+			g.warner("Additional property has multiple types; will be represented as an empty interface with no validation")
+
+			return map[string]any{}
+		}
+
+		switch prop.AdditionalProperties.Type[0] {
+		case schemas.TypeNameString:
+			return map[string]string{}
+
+		case schemas.TypeNameArray:
+			return map[string][]any{}
+
+		case schemas.TypeNameNumber:
+			return map[string]float64{}
+
+		case schemas.TypeNameInteger:
+			return map[string]int{}
+
+		case schemas.TypeNameBoolean:
+			return map[string]bool{}
+
+		default:
+			return map[string]any{}
+		}
+	}
+
+	return prop.Default
+}
+
 func (g *schemaGenerator) generateTypeInline(
 	t *schemas.Type,
 	scope nameScope,

tests/data/core/objectAdditionalProperties.go.output

@@ -0,0 +1,30 @@
+// Code generated by github.com/atombender/go-jsonschema, DO NOT EDIT.
+
+package test
+
+import "encoding/json"
+
+type ObjectAdditionalProperties struct {
+	// Foo corresponds to the JSON schema field "foo".
+	Foo ObjectAdditionalPropertiesFoo `json:"foo,omitempty" yaml:"foo,omitempty" mapstructure:"foo,omitempty"`
+}
+
+type ObjectAdditionalPropertiesFoo map[string]string
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (j *ObjectAdditionalProperties) UnmarshalJSON(b []byte) error {
+	var raw map[string]interface{}
+	if err := json.Unmarshal(b, &raw); err != nil {
+		return err
+	}
+	type Plain ObjectAdditionalProperties
+	var plain Plain
+	if err := json.Unmarshal(b, &plain); err != nil {
+		return err
+	}
+	if v, ok := raw["foo"]; !ok || v == nil {
+		plain.Foo = map[string]string{}
+	}
+	*j = ObjectAdditionalProperties(plain)
+	return nil
+}

tests/data/core/objectAdditionalProperties.json

@@ -0,0 +1,14 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "properties": {
+      "foo": {
+          "type": "object",
+          "additionalProperties": {
+              "type": "string"
+          },
+          "default": {}
+      }
+  },
+  "additionalProperties": false
+}