Skip to content

Add NullSafeTypeAdapter to prevent TypeAdapter.nullSafe() from returning nested null-safe type adapters (#2729) #2731

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
eamonnmcmanus merged 1 commit into from
Sep 3, 2024
Merged

Add NullSafeTypeAdapter to prevent TypeAdapter.nullSafe() from returning nested null-safe type adapters (#2729) #2731

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
42 changes: 26 additions & 16 deletions gson/src/main/java/com/google/gson/TypeAdapter.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -289,24 +289,34 @@ public final T fromJsonTree(JsonElement jsonTree) {
* Note that we didn't need to check for nulls in our type adapter after we used nullSafe.
*/
public final TypeAdapter<T> nullSafe() {
return new TypeAdapter<T>() {
@Override
public void write(JsonWriter out, T value) throws IOException {
if (value == null) {
out.nullValue();
} else {
TypeAdapter.this.write(out, value);
}
if (!(this instanceof TypeAdapter.NullSafeTypeAdapter)) {
return new NullSafeTypeAdapter();
}
return this;
}

private final class NullSafeTypeAdapter extends TypeAdapter<T> {

@Marcono1234 Marcono1234 Sep 1, 2024

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

As suggested in #2729 (comment), do you want to take the chance and implement toString as well. I think at least some other adapters implement it, and it would then make it easier to see which adapter is wrapped by this one.

@lyubomyr-shaydariv lyubomyr-shaydariv Sep 1, 2024 •
edited
Loading

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@Marcono1234

Oh, I seem to have misterstood your toString() suggestion earlier leaving it out of scope (I mistakenly assumed it leads to a stack overflow error, but it doesn't).

Could you please suggest the NullSafeTypeAdapter.toString() pattern you'd like to see?

@lyubomyr-shaydariv lyubomyr-shaydariv Sep 2, 2024 •
edited
Loading

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

As suggested in #2729 (comment), do you want to take the chance and implement toString as well. I think at least some other adapters implement it, and it would then make it easier to see which adapter is wrapped by this one.

I applied the NullSafeTypeAdapter[%s] pattern you suggested in #2729 (comment).

@Override
public void write(JsonWriter out, T value) throws IOException {
if (value == null) {
out.nullValue();
} else {
TypeAdapter.this.write(out, value);
}
}

@Override
public T read(JsonReader reader) throws IOException {
if (reader.peek() == JsonToken.NULL) {
reader.nextNull();
return null;
}
return TypeAdapter.this.read(reader);
@Override
public T read(JsonReader reader) throws IOException {
if (reader.peek() == JsonToken.NULL) {
reader.nextNull();
return null;
}
};
return TypeAdapter.this.read(reader);
}

@Override
public String toString() {
return "NullSafeTypeAdapter[" + TypeAdapter.this + "]";
}
}
}
51 changes: 39 additions & 12 deletions gson/src/test/java/com/google/gson/TypeAdapterTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -28,23 +28,50 @@
public class TypeAdapterTest {
@Test
public void testNullSafe() throws IOException {
TypeAdapter<String> adapter =
new TypeAdapter<String>() {
@Override
public void write(JsonWriter out, String value) {
throw new AssertionError("unexpected call");
}

@Override
public String read(JsonReader in) {
throw new AssertionError("unexpected call");
}
}.nullSafe();
TypeAdapter<String> adapter = assertionErrorAdapter.nullSafe();

assertThat(adapter.toJson(null)).isEqualTo("null");
assertThat(adapter.fromJson("null")).isNull();
}

@Test
public void testNullSafe_ReturningSameInstanceOnceNullSafe() {
TypeAdapter<?> nullSafeAdapter = assertionErrorAdapter.nullSafe();

assertThat(nullSafeAdapter.nullSafe()).isSameInstanceAs(nullSafeAdapter);
assertThat(nullSafeAdapter.nullSafe().nullSafe()).isSameInstanceAs(nullSafeAdapter);
assertThat(nullSafeAdapter.nullSafe().nullSafe().nullSafe()).isSameInstanceAs(nullSafeAdapter);
}

@Test
public void testNullSafe_ToString() {
TypeAdapter<?> adapter = assertionErrorAdapter;

assertThat(adapter.toString()).isEqualTo("assertionErrorAdapter");
assertThat(adapter.nullSafe().toString())
.isEqualTo("NullSafeTypeAdapter[assertionErrorAdapter]");
assertThat(adapter.nullSafe().nullSafe().toString())
.isEqualTo("NullSafeTypeAdapter[assertionErrorAdapter]");
}

private static final TypeAdapter<String> assertionErrorAdapter =
new TypeAdapter<>() {
@Override
public void write(JsonWriter out, String value) {
throw new AssertionError("unexpected call");
}

@Override
public String read(JsonReader in) {
throw new AssertionError("unexpected call");
}

@Override
public String toString() {
return "assertionErrorAdapter";
}
};

/**
* Tests behavior when {@link TypeAdapter#write(JsonWriter, Object)} manually throws {@link
* IOException} which is not caused by writer usage.
Expand Down