feat: Normalize toJSON output by omitting fields set to their defau…

…lt values (#878)

* Normalize `toJSON` output by omitting fields set to their default values

* Avoid mapping arrays with the identity function

* Remove unnecessary undefined checks

* Fix tests

README.markdown

@@ -728,26 +728,15 @@ Foo.fromJSON({ bar: "" }); // => { bar: '' }
 Foo.fromJSON({ bar: "baz" }); // => { bar: 'baz' }
 ```
 
-When writing JSON, `ts-proto` currently does **not** normalize message when converting to JSON, other than omitting unset fields, but it may do so in the future.
+When writing JSON, `ts-proto` normalizes messages by omitting unset fields and fields set to their default values.
 
 ```typescript
-// Current ts-proto behavior
-Foo.toJSON({}); // => { }
-Foo.toJSON({ bar: undefined }); // => { }
-Foo.toJSON({ bar: "" }); // => { bar: '' } - note: this is the default value, but it's not omitted
-Foo.toJSON({ bar: "baz" }); // => { bar: 'baz' }
-```
-
-```typescript
-// Possible future behavior, where ts-proto would normalize message
 Foo.toJSON({}); // => { }
 Foo.toJSON({ bar: undefined }); // => { }
 Foo.toJSON({ bar: "" }); // => { } - note: omitting the default value, as expected
 Foo.toJSON({ bar: "baz" }); // => { bar: 'baz' }
 ```
 
-- Please open an issue if you need this behavior.
-
 # Well-Known Types
 
 Protobuf comes with several predefined message definitions, called "[Well-Known Types](https://developers.google.com/protocol-buffers/docs/reference/google.protobuf)".

integration/angular/simple-message.ts

@@ -48,7 +48,9 @@ export const SimpleMessage = {
 
   toJSON(message: SimpleMessage): unknown {
     const obj: any = {};
-    message.numberField !== undefined && (obj.numberField = Math.round(message.numberField));
+    if (message.numberField !== 0) {
+      obj.numberField = Math.round(message.numberField);
+    }
     return obj;
   },
 

integration/async-iterable-services-abort-signal/simple.ts

@@ -81,7 +81,9 @@ export const EchoMsg = {
 
   toJSON(message: EchoMsg): unknown {
     const obj: any = {};
-    message.body !== undefined && (obj.body = message.body);
+    if (message.body !== "") {
+      obj.body = message.body;
+    }
     return obj;
   },
 

integration/async-iterable-services/simple.ts

@@ -81,7 +81,9 @@ export const EchoMsg = {
 
   toJSON(message: EchoMsg): unknown {
     const obj: any = {};
-    message.body !== undefined && (obj.body = message.body);
+    if (message.body !== "") {
+      obj.body = message.body;
+    }
     return obj;
   },
 

integration/avoid-import-conflicts/simple.ts

@@ -123,9 +123,12 @@ export const Simple = {
 
   toJSON(message: Simple): unknown {
     const obj: any = {};
-    message.name !== undefined && (obj.name = message.name);
-    message.otherSimple !== undefined &&
-      (obj.otherSimple = message.otherSimple ? Simple3.toJSON(message.otherSimple) : undefined);
+    if (message.name !== "") {
+      obj.name = message.name;
+    }
+    if (message.otherSimple !== undefined) {
+      obj.otherSimple = Simple3.toJSON(message.otherSimple);
+    }
     return obj;
   },
 
@@ -197,8 +200,12 @@ export const SimpleEnums = {
 
   toJSON(message: SimpleEnums): unknown {
     const obj: any = {};
-    message.localEnum !== undefined && (obj.localEnum = simpleEnumToJSON(message.localEnum));
-    message.importEnum !== undefined && (obj.importEnum = simpleEnumToJSON5(message.importEnum));
+    if (message.localEnum !== 0) {
+      obj.localEnum = simpleEnumToJSON(message.localEnum);
+    }
+    if (message.importEnum !== 0) {
+      obj.importEnum = simpleEnumToJSON5(message.importEnum);
+    }
     return obj;
   },
 
@@ -255,7 +262,9 @@ export const FooServiceCreateRequest = {
 
   toJSON(message: FooServiceCreateRequest): unknown {
     const obj: any = {};
-    message.kind !== undefined && (obj.kind = fooServiceToJSON(message.kind));
+    if (message.kind !== 0) {
+      obj.kind = fooServiceToJSON(message.kind);
+    }
     return obj;
   },
 
@@ -311,7 +320,9 @@ export const FooServiceCreateResponse = {
 
   toJSON(message: FooServiceCreateResponse): unknown {
     const obj: any = {};
-    message.kind !== undefined && (obj.kind = fooServiceToJSON(message.kind));
+    if (message.kind !== 0) {
+      obj.kind = fooServiceToJSON(message.kind);
+    }
     return obj;
   },
 

integration/avoid-import-conflicts/simple2.ts

@@ -137,8 +137,12 @@ export const Simple = {
 
   toJSON(message: Simple): unknown {
     const obj: any = {};
-    message.name !== undefined && (obj.name = message.name);
-    message.age !== undefined && (obj.age = Math.round(message.age));
+    if (message.name !== "") {
+      obj.name = message.name;
+    }
+    if (message.age !== 0) {
+      obj.age = Math.round(message.age);
+    }
     return obj;
   },
 

integration/barrel-imports/bar.ts

@@ -57,8 +57,12 @@ export const Bar = {
 
   toJSON(message: Bar): unknown {
     const obj: any = {};
-    message.name !== undefined && (obj.name = message.name);
-    message.age !== undefined && (obj.age = Math.round(message.age));
+    if (message.name !== "") {
+      obj.name = message.name;
+    }
+    if (message.age !== 0) {
+      obj.age = Math.round(message.age);
+    }
     return obj;
   },
 

integration/barrel-imports/foo.ts

@@ -61,8 +61,12 @@ export const Foo = {
 
   toJSON(message: Foo): unknown {
     const obj: any = {};
-    message.name !== undefined && (obj.name = message.name);
-    message.bar !== undefined && (obj.bar = message.bar ? Bar.toJSON(message.bar) : undefined);
+    if (message.name !== "") {
+      obj.name = message.name;
+    }
+    if (message.bar !== undefined) {
+      obj.bar = Bar.toJSON(message.bar);
+    }
     return obj;
   },
 

integration/batching-with-context-esModuleInterop/batching.ts

@@ -87,10 +87,8 @@ export const BatchQueryRequest = {
 
   toJSON(message: BatchQueryRequest): unknown {
     const obj: any = {};
-    if (message.ids) {
-      obj.ids = message.ids.map((e) => e);
-    } else {
-      obj.ids = [];
+    if (message.ids?.length) {
+      obj.ids = message.ids;
     }
     return obj;
   },
@@ -147,10 +145,8 @@ export const BatchQueryResponse = {
 
   toJSON(message: BatchQueryResponse): unknown {
     const obj: any = {};
-    if (message.entities) {
-      obj.entities = message.entities.map((e) => e ? Entity.toJSON(e) : undefined);
-    } else {
-      obj.entities = [];
+    if (message.entities?.length) {
+      obj.entities = message.entities.map((e) => Entity.toJSON(e));
     }
     return obj;
   },
@@ -207,10 +203,8 @@ export const BatchMapQueryRequest = {
 
   toJSON(message: BatchMapQueryRequest): unknown {
     const obj: any = {};
-    if (message.ids) {
-      obj.ids = message.ids.map((e) => e);
-    } else {
-      obj.ids = [];
+    if (message.ids?.length) {
+      obj.ids = message.ids;
     }
     return obj;
   },
@@ -277,11 +271,14 @@ export const BatchMapQueryResponse = {
 
   toJSON(message: BatchMapQueryResponse): unknown {
     const obj: any = {};
-    obj.entities = {};
     if (message.entities) {
-      Object.entries(message.entities).forEach(([k, v]) => {
-        obj.entities[k] = Entity.toJSON(v);
-      });
+      const entries = Object.entries(message.entities);
+      if (entries.length > 0) {
+        obj.entities = {};
+        entries.forEach(([k, v]) => {
+          obj.entities[k] = Entity.toJSON(v);
+        });
+      }
     }
     return obj;
   },
@@ -356,8 +353,12 @@ export const BatchMapQueryResponse_EntitiesEntry = {
 
   toJSON(message: BatchMapQueryResponse_EntitiesEntry): unknown {
     const obj: any = {};
-    message.key !== undefined && (obj.key = message.key);
-    message.value !== undefined && (obj.value = message.value ? Entity.toJSON(message.value) : undefined);
+    if (message.key !== "") {
+      obj.key = message.key;
+    }
+    if (message.value !== undefined) {
+      obj.value = Entity.toJSON(message.value);
+    }
     return obj;
   },
 
@@ -420,7 +421,9 @@ export const GetOnlyMethodRequest = {
 
   toJSON(message: GetOnlyMethodRequest): unknown {
     const obj: any = {};
-    message.id !== undefined && (obj.id = message.id);
+    if (message.id !== "") {
+      obj.id = message.id;
+    }
     return obj;
   },
 
@@ -476,7 +479,9 @@ export const GetOnlyMethodResponse = {
 
   toJSON(message: GetOnlyMethodResponse): unknown {
     const obj: any = {};
-    message.entity !== undefined && (obj.entity = message.entity ? Entity.toJSON(message.entity) : undefined);
+    if (message.entity !== undefined) {
+      obj.entity = Entity.toJSON(message.entity);
+    }
     return obj;
   },
 
@@ -534,7 +539,9 @@ export const WriteMethodRequest = {
 
   toJSON(message: WriteMethodRequest): unknown {
     const obj: any = {};
-    message.id !== undefined && (obj.id = message.id);
+    if (message.id !== "") {
+      obj.id = message.id;
+    }
     return obj;
   },
 
@@ -644,8 +651,12 @@ export const Entity = {
 
   toJSON(message: Entity): unknown {
     const obj: any = {};
-    message.id !== undefined && (obj.id = message.id);
-    message.name !== undefined && (obj.name = message.name);
+    if (message.id !== "") {
+      obj.id = message.id;
+    }
+    if (message.name !== "") {
+      obj.name = message.name;
+    }
     return obj;
   },