fix: Always include children of new entities. (#114)

...if the list isn't empty.

src/fields/listField.ts

@@ -82,6 +82,7 @@ export function newListFieldState<T, K extends keyof T, U>(
       return _tick.value > 0 && _childTick.value > 0 ? ((parentInstance[key] ?? []) as any as U[]) : fail();
     },
 
+    _kind: "list",
     _focused: false,
     _readOnly: false,
     _loading: false,

src/fields/objectField.ts

@@ -341,8 +341,10 @@ export function newObjectState<T, P = any>(
           // If the caller used useFormState.ifUndefined to provide some default values, then those keys may not
           // look dirty, but if we're new we should include them anyway.
           (this.isNewEntity && (f as any)._kind === "value" && f.value !== undefined) ||
-          // And unless they're empty sub-objects
-          (this.isNewEntity && (f as any)._kind === "object" && Object.entries(f.changedValue).length > 0)
+          // ...or they're non-empty sub-objects
+          (this.isNewEntity && (f as any)._kind === "object" && Object.entries(f.changedValue).length > 0) ||
+          // ...or they're non-empty sub-lists
+          (this.isNewEntity && (f as any)._kind === "list" && f.value?.length > 0)
         ) {
           result[f.key] = f.changedValue;
         }

src/formState.test.tsx

@@ -1232,6 +1232,25 @@ describe("formState", () => {
     expect(formState.changedValue).toEqual({ firstName: "f" });
   });
 
+  it("changedValue includes initialized-and-unchanged list fields", () => {
+    // Given a new author that is initialized with a new book
+    const formState = createObjectState(authorWithBooksConfig, {
+      books: [{ title: "t1" }],
+    });
+    // Then changedValue realizes that even though `books` is not changed, it should be included
+    expect(formState.books.dirty).toBe(false);
+    expect(formState.changedValue).toEqual({ books: [{ title: "t1" }] });
+  });
+
+  it("changedValue skips initialized-and-unchanged list fields that are empty", () => {
+    // Given a new author that is initialized with no books
+    const formState = createObjectState(authorWithBooksConfig, {
+      books: [],
+    });
+    // Then changedValue doesn't include the books
+    expect(formState.changedValue).toEqual({});
+  });
+
   it("changedValue includes new entity nested fields", () => {
     // Given a new author with an address FK
     const formState = createObjectState(authorWithAddressFkConfig, {