diff --git a/adapters/src/main/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactory.java b/adapters/src/main/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactory.java index 1019a8c..16b819b 100644 --- a/adapters/src/main/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactory.java +++ b/adapters/src/main/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactory.java @@ -95,38 +95,52 @@ import javax.annotation.Nullable; *
  • Each type identifier must be unique. * * - *

    For best performance type information should be the first field in the object. Otherwise Moshi - * must reprocess the JSON stream once it knows the object's type. + *

    For best performance type information should be the first field in the object. Otherwise + * Moshi must reprocess the JSON stream once it knows the object's type. * - *

    If an unknown subtype is encountered when decoding, this will throw a {@link - * JsonDataException}. If an unknown type is encountered when encoding, this will throw an {@link - * IllegalArgumentException}. If the same subtype has multiple labels the first one is used when - * encoding. + *

    If an unknown subtype is encountered when decoding: + *

    * - *

    If you want to specify a custom unknown fallback for decoding, you can do so via - * {@link #withDefaultValue(Object)}. This instance should be immutable, as it is shared. + *

    If an unknown type is encountered when encoding: + *

    + * + *

    If the same subtype has multiple labels the first one is used when encoding. */ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Factory { + /** + * Thin wrapper around {@link JsonAdapter} to allow {@link PolymorphicJsonAdapter} to + * distinguish between {@code JsonAdapter} added due to a {@code defaultValue} or added + * by users of {@link PolymorphicJsonAdapterFactory}. + */ + private abstract static class DefaultJsonAdapter extends JsonAdapter { + } + final Class baseType; final String labelKey; final List labels; final List subtypes; - @Nullable final T defaultValue; - final boolean defaultValueSet; + @Nullable final JsonAdapter fallbackJsonAdapter; PolymorphicJsonAdapterFactory( Class baseType, String labelKey, List labels, List subtypes, - @Nullable T defaultValue, - boolean defaultValueSet) { + @Nullable JsonAdapter fallbackJsonAdapter) { this.baseType = baseType; this.labelKey = labelKey; this.labels = labels; this.subtypes = subtypes; - this.defaultValue = defaultValue; - this.defaultValueSet = defaultValueSet; + this.fallbackJsonAdapter = fallbackJsonAdapter; } /** @@ -143,14 +157,11 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto labelKey, Collections.emptyList(), Collections.emptyList(), - null, - false); + null); } /** - * Returns a new factory that decodes instances of {@code subtype}. When an unknown type is found - * during encoding an {@linkplain IllegalArgumentException} will be thrown. When an unknown label - * is found during decoding a {@linkplain JsonDataException} will be thrown. + * Returns a new factory that decodes instances of {@code subtype}. */ public PolymorphicJsonAdapterFactory withSubtype(Class subtype, String label) { if (subtype == null) throw new NullPointerException("subtype == null"); @@ -166,21 +177,49 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto labelKey, newLabels, newSubtypes, - defaultValue, - defaultValueSet); + fallbackJsonAdapter); } /** - * Returns a new factory that with default to {@code defaultValue} upon decoding of unrecognized - * labels. The default value should be immutable. + * Returns a new factory that with default to {@code fallbackJsonAdapter.fromJson(reader)} + * upon decoding of unrecognized labels. + * + *

    The {@link JsonReader} instance will not be automatically consumed, so sure to consume it + * within your implementation of {@link JsonAdapter#fromJson(JsonReader)} */ - public PolymorphicJsonAdapterFactory withDefaultValue(@Nullable T defaultValue) { + public PolymorphicJsonAdapterFactory withFallbackJsonAdapter( + @Nullable JsonAdapter fallbackJsonAdapter) { return new PolymorphicJsonAdapterFactory<>(baseType, labelKey, labels, subtypes, - defaultValue, - true); + fallbackJsonAdapter); + } + + /** + * Returns a new factory that will default to {@code defaultValue} upon decoding of unrecognized + * labels. The default value should be immutable. + */ + public PolymorphicJsonAdapterFactory withDefaultValue(@Nullable T defaultValue) { + return withFallbackJsonAdapter(buildFallbackJsonAdapter(defaultValue)); + } + + private JsonAdapter buildFallbackJsonAdapter(final T defaultValue) { + return new DefaultJsonAdapter() { + @Nullable + @Override + public Object fromJson(JsonReader reader) throws IOException { + reader.skipValue(); + return defaultValue; + } + + @Override + public void toJson(JsonWriter writer, @Nullable Object value) throws IOException { + throw new IOException("This method should never be called. " + + "If you find this on your stacktraces please report it " + + "to the https://github.com/square/moshi project"); + } + }; } @Override @@ -198,8 +237,7 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto labels, subtypes, jsonAdapters, - defaultValue, - defaultValueSet + fallbackJsonAdapter ).nullSafe(); } @@ -208,8 +246,7 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto final List labels; final List subtypes; final List> jsonAdapters; - @Nullable final Object defaultValue; - final boolean defaultValueSet; + @Nullable final JsonAdapter fallbackJsonAdapter; /** Single-element options containing the label's key only. */ final JsonReader.Options labelKeyOptions; @@ -220,14 +257,12 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto List labels, List subtypes, List> jsonAdapters, - @Nullable Object defaultValue, - boolean defaultValueSet) { + @Nullable JsonAdapter fallbackJsonAdapter) { this.labelKey = labelKey; this.labels = labels; this.subtypes = subtypes; this.jsonAdapters = jsonAdapters; - this.defaultValue = defaultValue; - this.defaultValueSet = defaultValueSet; + this.fallbackJsonAdapter = fallbackJsonAdapter; this.labelKeyOptions = JsonReader.Options.of(labelKey); this.labelOptions = JsonReader.Options.of(labels.toArray(new String[0])); @@ -243,10 +278,10 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto peeked.close(); } if (labelIndex == -1) { - reader.skipValue(); - return defaultValue; + return this.fallbackJsonAdapter.fromJson(reader); + } else { + return jsonAdapters.get(labelIndex).fromJson(reader); } - return jsonAdapters.get(labelIndex).fromJson(reader); } private int labelIndex(JsonReader reader) throws IOException { @@ -259,7 +294,7 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto } int labelIndex = reader.selectString(labelOptions); - if (labelIndex == -1 && !defaultValueSet) { + if (labelIndex == -1 && this.fallbackJsonAdapter == null) { throw new JsonDataException("Expected one of " + labels + " for key '" @@ -277,18 +312,27 @@ public final class PolymorphicJsonAdapterFactory implements JsonAdapter.Facto @Override public void toJson(JsonWriter writer, Object value) throws IOException { Class type = value.getClass(); int labelIndex = subtypes.indexOf(type); + final JsonAdapter adapter; if (labelIndex == -1) { - throw new IllegalArgumentException("Expected one of " - + subtypes - + " but found " - + value - + ", a " - + value.getClass() - + ". Register this subtype."); + if (fallbackJsonAdapter == null || fallbackJsonAdapter instanceof DefaultJsonAdapter) { + throw new IllegalArgumentException("Expected one of " + + subtypes + + " but found " + + value + + ", a " + + value.getClass() + + ". Register this subtype."); + } else { + adapter = fallbackJsonAdapter; + } + } else { + adapter = jsonAdapters.get(labelIndex); } - JsonAdapter adapter = jsonAdapters.get(labelIndex); + writer.beginObject(); - writer.name(labelKey).value(labels.get(labelIndex)); + if (adapter != fallbackJsonAdapter) { + writer.name(labelKey).value(labels.get(labelIndex)); + } int flattenToken = writer.beginFlatten(); adapter.toJson(writer, value); writer.endFlatten(flattenToken); diff --git a/adapters/src/test/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactoryTest.java b/adapters/src/test/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactoryTest.java index ffc479e..dd01ef1 100644 --- a/adapters/src/test/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactoryTest.java +++ b/adapters/src/test/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactoryTest.java @@ -18,6 +18,7 @@ package com.squareup.moshi.adapters; import com.squareup.moshi.JsonAdapter; import com.squareup.moshi.JsonDataException; import com.squareup.moshi.JsonReader; +import com.squareup.moshi.JsonWriter; import com.squareup.moshi.Moshi; import java.io.IOException; import java.util.Collections; @@ -25,6 +26,8 @@ import java.util.Map; import okio.Buffer; import org.junit.Test; +import javax.annotation.Nullable; + import static org.assertj.core.api.Assertions.assertThat; import static org.junit.Assert.fail; @@ -105,6 +108,35 @@ public final class PolymorphicJsonAdapterFactoryTest { assertThat(message).isNull(); } + @Test public void specifiedFallbackJsonAdapter() throws IOException { + Moshi moshi = new Moshi.Builder() + .add(PolymorphicJsonAdapterFactory.of(Message.class, "type") + .withSubtype(Success.class, "success") + .withSubtype(Error.class, "error") + .withFallbackJsonAdapter(new JsonAdapter() { + @Override + public Object fromJson(JsonReader reader) throws IOException { + reader.skipValue(); + return new EmptyMessage(); + } + + @Override + public void toJson(JsonWriter writer, @Nullable Object value) { + throw new RuntimeException("Not implemented as not needed for the test"); + } + }) + ) + .build(); + JsonAdapter adapter = moshi.adapter(Message.class); + + JsonReader reader = + JsonReader.of(new Buffer().writeUtf8("{\"type\":\"data\",\"value\":\"Okay!\"}")); + + Message message = adapter.fromJson(reader); + assertThat(message).isInstanceOf(EmptyMessage.class); + assertThat(reader.peek()).isEqualTo(JsonReader.Token.END_DOCUMENT); + } + @Test public void unregisteredSubtype() { Moshi moshi = new Moshi.Builder() .add(PolymorphicJsonAdapterFactory.of(Message.class, "type") @@ -125,6 +157,52 @@ public final class PolymorphicJsonAdapterFactoryTest { } } + @Test public void unregisteredSubtypeWithDefaultValue() { + Error fallbackError = new Error(Collections.emptyMap()); + Moshi moshi = new Moshi.Builder() + .add(PolymorphicJsonAdapterFactory.of(Message.class, "type") + .withSubtype(Success.class, "success") + .withSubtype(Error.class, "error") + .withDefaultValue(fallbackError)) + .build(); + JsonAdapter adapter = moshi.adapter(Message.class); + + try { + adapter.toJson(new EmptyMessage()); + } catch (IllegalArgumentException expected) { + assertThat(expected).hasMessage("Expected one of [class" + + " com.squareup.moshi.adapters.PolymorphicJsonAdapterFactoryTest$Success, class" + + " com.squareup.moshi.adapters.PolymorphicJsonAdapterFactoryTest$Error] but found" + + " EmptyMessage, a class" + + " com.squareup.moshi.adapters.PolymorphicJsonAdapterFactoryTest$EmptyMessage. Register" + + " this subtype."); + } + } + + @Test public void unregisteredSubtypeWithFallbackJsonAdapter() { + Moshi moshi = new Moshi.Builder() + .add(PolymorphicJsonAdapterFactory.of(Message.class, "type") + .withSubtype(Success.class, "success") + .withSubtype(Error.class, "error") + .withFallbackJsonAdapter(new JsonAdapter() { + @Nullable + @Override + public Object fromJson(JsonReader reader) { + throw new RuntimeException("Not implemented as not needed for the test"); + } + + @Override + public void toJson(JsonWriter writer, @Nullable Object value) throws IOException { + writer.name("type").value("injected by fallbackJsonAdapter"); + } + })) + .build(); + JsonAdapter adapter = moshi.adapter(Message.class); + + String json = adapter.toJson(new EmptyMessage()); + assertThat(json).isEqualTo("{\"type\":\"injected by fallbackJsonAdapter\"}"); + } + @Test public void nonStringLabelValue() throws IOException { Moshi moshi = new Moshi.Builder() .add(PolymorphicJsonAdapterFactory.of(Message.class, "type")