Support readOnly / writeOnly.

generator.go

@@ -191,12 +191,21 @@ func (g *Generator) processObject(name string, schema *Schema) (typ string, err
 		if err != nil {
 			return "", err
 		}
+
+		access := Access_RW
+		if prop.ReadOnly {
+			access = Access_RO
+		} else if prop.WriteOnly {
+			access = Access_WO
+		}
+
 		f := Field{
 			Name:        fieldName,
 			JSONName:    propKey,
 			Type:        fieldType,
 			Required:    contains(schema.Required, propKey),
 			Description: prop.Description,
+			Access:      access,
 		}
 		if f.Required {
 			strct.GenerateCode = true
@@ -384,6 +393,14 @@ type Struct struct {
 	AdditionalType string
 }
 
+type Access int
+
+const (
+	Access_RW Access = iota
+	Access_RO
+	Access_WO
+)
+
 // Field defines the data required to generate a field in Go.
 type Field struct {
 	// The golang name, e.g. "Address1"
@@ -395,5 +412,8 @@ type Field struct {
 	Type string
 	// Required is set to true when the field is required.
 	Required    bool
+	// Access type, either R/W (default), R/O, or W/O.
+	Access Access
+
 	Description string
 }

jsonschema.go

@@ -43,6 +43,11 @@ type Schema struct {
 	// "additionalProperties": false
 	AdditionalPropertiesBool *bool `json:"-"`
 
+	// ReadOnly and WriteOnly specify access to a field.
+	// https://json-schema.org/draft-07/json-schema-validation.html#rfc.section.10.3
+	ReadOnly   bool
+	WriteOnly  bool
+
 	AnyOf []*Schema
 	AllOf []*Schema
 	OneOf []*Schema

output.go

@@ -83,12 +83,23 @@ func Output(w io.Writer, g *Generator, pkg string) {
 			if f.Required {
 				omitempty = ""
 			}
+			schemaTags := []string{}
+			if f.Access == Access_RO {
+				schemaTags = append(schemaTags, "readonly")
+			} else if f.Access == Access_WO {
+				schemaTags = append(schemaTags, "writeonly")
+			}
+
+			schemaTag := ""
+			if len(schemaTags) > 0 {
+				schemaTag = fmt.Sprintf(" jsonSchema:\"%s\"", strings.Join(schemaTags, ","))
+			}
 
 			if f.Description != "" {
 				outputFieldDescriptionComment(f.Description, w)
 			}
 
-			fmt.Fprintf(w, "  %s %s `json:\"%s%s\"`\n", f.Name, f.Type, f.JSONName, omitempty)
+			fmt.Fprintf(w, "  %s %s `json:\"%s%s\"%s`\n", f.Name, f.Type, f.JSONName, omitempty, schemaTag)
 		}
 
 		fmt.Fprintln(w, "}")

test/example1.json

@@ -24,6 +24,14 @@
             },
             "minItems": 1,
             "uniqueItems": true
+        },
+        "inStock": {
+            "type": "boolean",
+            "readOnly": true
+        },
+        "couponCode": {
+            "type": "string",
+            "writeOnly": true
         }
     },
     "required": [

test/example1_test.go

@@ -1,9 +1,11 @@
 package test
 
 import (
+	"strings"
 	"encoding/json"
-	"testing"
 	"github.com/a-h/generate/test/example1_gen"
+	"reflect"
+	"testing"
 )
 
 func TestExample1(t *testing.T) {
@@ -45,3 +47,24 @@ func TestExample1(t *testing.T) {
 		}
 	}
 }
+
+func TestExample1Access(t *testing.T) {
+	fs := reflect.VisibleFields(reflect.TypeOf(example1.Product{}))
+	for _, f := range fs {
+		if f.Name == "CouponCode" {
+			if v, ok := f.Tag.Lookup("jsonSchema"); !ok {
+				t.Fatal("Expected CouponCode field to have jsonSchema tag")
+			} else if !strings.Contains(v, "writeonly") {
+				t.Fatalf("CouponCode's json %q doesn't specify writeonly", v)
+			}
+		}
+
+		if f.Name == "InStock" {
+			if v, ok := f.Tag.Lookup("jsonSchema"); !ok {
+				t.Fatal("Expected InStock field to have jsonSchema tag")
+			} else if !strings.Contains(v, "readonly") {
+				t.Fatalf("InStock's json %q doesn't specify readonly", v)
+			}
+		}
+	}
+}