[#180] Add a JsonCodec

src/main/java/io/r2dbc/h2/codecs/DefaultCodecs.java

@@ -124,6 +124,7 @@ static List<Codec<?>> createCodecs(Client client, ClassLoader classLoader, Codec
                 new DoubleCodec(),
                 new FloatCodec(),
                 new IntegerCodec(),
+                new JsonCodec(),
                 new LocalDateCodec(),
                 new LocalDateTimeCodec(client),
                 new LocalTimeCodec(),

src/main/java/io/r2dbc/h2/codecs/JsonCodec.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.r2dbc.h2.codecs;
+
+import io.r2dbc.h2.util.Assert;
+import org.h2.value.Value;
+import org.h2.value.ValueJson;
+
+final class JsonCodec extends AbstractCodec<String> {
+
+    JsonCodec() {
+        super(String.class);
+    }
+
+    @Override
+    boolean doCanDecode(int dataType) {
+        return Value.JSON == dataType;
+    }
+
+    @Override
+    String doDecode(Value value, Class<? extends String> type) {
+        return value.getString();
+    }
+
+    @Override
+    Value doEncode(String value) {
+        return ValueJson.fromJson(Assert.requireNonNull(value, "value must not be null"));
+    }
+}

src/test/java/io/r2dbc/h2/codecs/DefaultCodecsTest.java

@@ -80,6 +80,7 @@ void createCodecsWithNonOptionalCodecsAndNoDuplicates() throws Exception {
             DoubleCodec.class,
             FloatCodec.class,
             IntegerCodec.class,
+            JsonCodec.class,
             LocalDateCodec.class,
             LocalDateTimeCodec.class,
             LocalTimeCodec.class,
@@ -116,6 +117,7 @@ void createCodecsWithOptionalCodecsAndNoDuplicates() throws Exception {
             FloatCodec.class,
             GeometryCodec.class,
             IntegerCodec.class,
+            JsonCodec.class,
             LocalDateCodec.class,
             LocalDateTimeCodec.class,
             LocalTimeCodec.class,

src/test/java/io/r2dbc/h2/codecs/JsonCodecTest.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.r2dbc.h2.codecs;
+
+import org.h2.value.Value;
+import org.h2.value.ValueInt;
+import org.h2.value.ValueJson;
+import org.h2.value.ValueNull;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+final class JsonCodecTest {
+
+    @Test
+    void decode() {
+        assertThat(new JsonCodec().decode(ValueJson.fromJson("{}"), String.class))
+            .isEqualTo("{}");
+    }
+
+    @Test
+    void doCanDecode() {
+        JsonCodec codec = new JsonCodec();
+
+        assertThat(codec.doCanDecode(Value.JSON)).isTrue();
+        assertThat(codec.doCanDecode(Value.DOUBLE)).isFalse();
+    }
+
+    @Test
+    void doEncode() {
+        assertThat(new JsonCodec().doEncode("{}"))
+            .isEqualTo(ValueJson.fromJson("{}"));
+    }
+
+    @Test
+    void doEncodeNoValue() {
+        assertThatIllegalArgumentException().isThrownBy(() -> new JsonCodec().doEncode(null))
+            .withMessage("value must not be null");
+    }
+
+    @Test
+    void encodeNull() {
+        assertThat(new JsonCodec().encodeNull())
+            .isEqualTo(ValueNull.INSTANCE);
+    }
+}