add enum tag to jsonschema (#962)

* fix jsonschema tests

* ensure all run during PR Github Action

* add test for struct to schema

* add support for enum tag

* support nullable tag

.github/workflows/pr.yml

@@ -22,6 +22,6 @@ jobs:
       with:
         version: v1.64.5
     - name: Run tests
-      run: go test -race -covermode=atomic -coverprofile=coverage.out -v .
+      run: go test -race -covermode=atomic -coverprofile=coverage.out -v ./...
     - name: Upload coverage reports to Codecov
       uses: codecov/codecov-action@v4

jsonschema/json.go

@@ -46,6 +46,8 @@ type Definition struct {
 	// additionalProperties: false
 	// additionalProperties: jsonschema.Definition{Type: jsonschema.String}
 	AdditionalProperties any `json:"additionalProperties,omitempty"`
+	// Whether the schema is nullable or not.
+	Nullable bool `json:"nullable,omitempty"`
 }
 
 func (d *Definition) MarshalJSON() ([]byte, error) {
@@ -139,6 +141,16 @@ func reflectSchemaObject(t reflect.Type) (*Definition, error) {
 		if description != "" {
 			item.Description = description
 		}
+		enum := field.Tag.Get("enum")
+		if enum != "" {
+			item.Enum = strings.Split(enum, ",")
+		}
+
+		if n := field.Tag.Get("nullable"); n != "" {
+			nullable, _ := strconv.ParseBool(n)
+			item.Nullable = nullable
+		}
+
 		properties[jsonTag] = *item
 
 		if s := field.Tag.Get("required"); s != "" {

jsonschema/json_test.go

@@ -17,7 +17,7 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 		{
 			name: "Test with empty Definition",
 			def:  jsonschema.Definition{},
-			want: `{"properties":{}}`,
+			want: `{}`,
 		},
 		{
 			name: "Test with Definition properties set",
@@ -35,8 +35,7 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 				"description":"A string type",
 				"properties":{
 						"name":{
-         "type":"string",
+							"type":"string"
-         "properties":{}
 						}
 				}
 			}`,
@@ -66,12 +65,10 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 							"type":"object",
 							"properties":{
 									"name":{
-               "type":"string",
+										"type":"string"
-               "properties":{}
 									},
 									"age":{
-               "type":"integer",
+										"type":"integer"
-               "properties":{}
 									}
 							}
 						}
@@ -114,23 +111,19 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 							"type":"object",
 							"properties":{
 									"name":{
-               "type":"string",
+										"type":"string"
-               "properties":{}
 									},
 									"age":{
-               "type":"integer",
+										"type":"integer"
-               "properties":{}
 									},
 									"address":{
 										"type":"object",
 										"properties":{
 												"city":{
-                     "type":"string",
+													"type":"string"
-                     "properties":{}
 												},
 												"country":{
-                     "type":"string",
+													"type":"string"
-                     "properties":{}
 												}
 										}
 									}
@@ -155,15 +148,11 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 			want: `{
 				"type":"array",
 				"items":{
-      "type":"string",
+						"type":"string"
-      "properties":{
-         
-      }
 				},
 				"properties":{
 						"name":{
-         "type":"string",
+							"type":"string"
-         "properties":{}
 						}
 				}
 			}`,
@@ -193,6 +182,185 @@ func TestDefinition_MarshalJSON(t *testing.T) {
 	}
 }
 
+func TestStructToSchema(t *testing.T) {
+	tests := []struct {
+		name string
+		in   any
+		want string
+	}{
+		{
+			name: "Test with empty struct",
+			in:   struct{}{},
+			want: `{
+				"type":"object",
+				"additionalProperties":false
+			}`,
+		},
+		{
+			name: "Test with struct containing many fields",
+			in: struct {
+				Name   string  `json:"name"`
+				Age    int     `json:"age"`
+				Active bool    `json:"active"`
+				Height float64 `json:"height"`
+				Cities []struct {
+					Name  string `json:"name"`
+					State string `json:"state"`
+				} `json:"cities"`
+			}{
+				Name: "John Doe",
+				Age:  30,
+				Cities: []struct {
+					Name  string `json:"name"`
+					State string `json:"state"`
+				}{
+					{Name: "New York", State: "NY"},
+					{Name: "Los Angeles", State: "CA"},
+				},
+			},
+			want: `{
+				"type":"object",
+				"properties":{
+					"name":{
+						"type":"string"
+					},
+					"age":{
+						"type":"integer"
+					},
+					"active":{
+						"type":"boolean"
+					},
+					"height":{
+						"type":"number"
+					},
+					"cities":{
+						"type":"array",
+						"items":{
+							"additionalProperties":false,
+							"type":"object",
+							"properties":{
+								"name":{
+									"type":"string"
+								},
+								"state":{
+									"type":"string"
+								}
+							},
+							"required":["name","state"]
+						}
+					}
+				},
+				"required":["name","age","active","height","cities"],
+				"additionalProperties":false
+			}`,
+		},
+		{
+			name: "Test with description tag",
+			in: struct {
+				Name string `json:"name" description:"The name of the person"`
+			}{
+				Name: "John Doe",
+			},
+			want: `{
+				"type":"object",
+				"properties":{
+					"name":{
+						"type":"string",
+						"description":"The name of the person"
+					}
+				},
+				"required":["name"],
+				"additionalProperties":false
+			}`,
+		},
+		{
+			name: "Test with required tag",
+			in: struct {
+				Name string `json:"name" required:"false"`
+			}{
+				Name: "John Doe",
+			},
+			want: `{
+				"type":"object",
+				"properties":{
+					"name":{
+						"type":"string"
+					}
+				},
+				"additionalProperties":false
+			}`,
+		},
+		{
+			name: "Test with enum tag",
+			in: struct {
+				Color string `json:"color" enum:"red,green,blue"`
+			}{
+				Color: "red",
+			},
+			want: `{
+				"type":"object",
+				"properties":{
+					"color":{
+						"type":"string",
+						"enum":["red","green","blue"]
+					}
+				},
+				"required":["color"],
+				"additionalProperties":false
+			}`,
+		},
+		{
+			name: "Test with nullable tag",
+			in: struct {
+				Name *string `json:"name" nullable:"true"`
+			}{
+				Name: nil,
+			},
+			want: `{
+
+				"type":"object",
+				"properties":{
+					"name":{
+						"type":"string",
+						"nullable":true
+					}
+				},
+				"required":["name"],
+				"additionalProperties":false
+			}`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			wantBytes := []byte(tt.want)
+
+			schema, err := jsonschema.GenerateSchemaForType(tt.in)
+			if err != nil {
+				t.Errorf("Failed to generate schema: error = %v", err)
+				return
+			}
+
+			var want map[string]interface{}
+			err = json.Unmarshal(wantBytes, &want)
+			if err != nil {
+				t.Errorf("Failed to Unmarshal JSON: error = %v", err)
+				return
+			}
+
+			got := structToMap(t, schema)
+			gotPtr := structToMap(t, &schema)
+
+			if !reflect.DeepEqual(got, want) {
+				t.Errorf("MarshalJSON() got = %v, want %v", got, want)
+			}
+			if !reflect.DeepEqual(gotPtr, want) {
+				t.Errorf("MarshalJSON() gotPtr = %v, want %v", gotPtr, want)
+			}
+		})
+	}
+}
+
 func structToMap(t *testing.T, v any) map[string]any {
 	t.Helper()
 	gotBytes, err := json.Marshal(v)