generate: handle map[string]any types correctly. (#325)

When an openapi field includes an `additionalProperties` key, it
represents a map to the type specified in the schema reference. We
already correctly handle the special case of mapping a string to a slice
of the referenced type as a `map[string][]type`, but not the case where
the nested type isn't a slice. This patch adds logic for the missing
`map[string[type` case.

Author: jmcarp

internal/generate/types.go

@@ -490,14 +490,25 @@ func createTypeObject(schema *openapi3.Schema, name, typeName, description strin
 			typeName = fmt.Sprintf("%s%s", name, strcase.ToCamel(k))
 		}
 
-		// When additional properties is set and is type array, it means
-		// the type will be a map.
-		// TODO correctness: Currently our API spec does not specify what
-		// type the key will be, so we set it to string to avoid errors.
-		// If the type of the key is defined in our spec in the future,
-		// this should be changed to reflect that type.
-		if isObjectArray(v) {
-			typeName = fmt.Sprintf("map[string][]%s", typeName)
+		// When `additionalProperties` is set, the type will be a map.
+		// See the spec for details: https://spec.openapis.org/oas/v3.0.3.html#x4-7-24-3-3-model-with-map-dictionary-properties.
+		//
+		// TODO correctness: Currently our API spec does not specify
+		// what type the key will be, so we set it to string to avoid
+		// errors.  If the type of the key is defined in our spec in
+		// the future, this should be changed to reflect that type.
+		if v.Value.AdditionalProperties.Schema != nil {
+			if v.Value.AdditionalProperties.Schema.Value.Type.Is("array") {
+				// When `additionalProperties` has a schema of
+				// type "array", use a map of string to a slice
+				// of the nested type.
+				typeName = fmt.Sprintf("map[string][]%s", typeName)
+			} else {
+				// If the schema type isn't explicitly set to
+				// "array", use a map of string to the nested
+				// type.
+				typeName = fmt.Sprintf("map[string]%s", typeName)
+			}
 		}
 
 		// If a type is nullable we'll want a pointer

internal/generate/utils.go

@@ -53,14 +53,6 @@ func isLocalObject(v *openapi3.SchemaRef) bool {
 	return v.Ref == "" && v.Value.Type.Is("object") && len(v.Value.Properties) > 0
 }
 
-func isObjectArray(v *openapi3.SchemaRef) bool {
-	if v.Value.AdditionalProperties.Schema != nil {
-		return v.Value.AdditionalProperties.Schema.Value.Type.Is("array")
-	}
-
-	return false
-}
-
 func isNullableArray(v *openapi3.SchemaRef) bool {
 	return v.Value.Type.Is("array") && v.Value.Nullable
 }