add support for enum data type in MySQL (#620)

Signed-off-by: Billy Yuan <billy112487983@gmail.com>

Author: BillyYccc

vertx-mysql-client/src/main/asciidoc/index.adoc

@@ -347,6 +347,24 @@ The {@link io.vertx.sqlclient.data.Numeric} Java type is used to represent the M
 {@link examples.MySQLClientExamples#numericExample(io.vertx.sqlclient.Row)}
 ----
 
+=== Handling ENUM
+
+MySQL supports ENUM data type and the client retrieves these types as String data type.
+
+You can encode Java enums as String like this:
+
+[source,$lang]
+----
+{@link examples.MySQLClientExamples#enumeratedType01Example}
+----
+
+You can retrieve the ENUM column as Java enums like this:
+
+[source,$lang]
+----
+{@link examples.MySQLClientExamples#enumeratedType02Example}
+----
+
 === Handling GEOMETRY
 
 MYSQL `GEOMETRY` data type is also supported, Here are some examples showing that you can handle the geometry data in Well-Known Text (WKT) format or Well-Known Binary (WKB) format, the data are decoded as MySQL TEXT OR BLOB data type. There are many great third-party libraries for handling data in this format.

vertx-mysql-client/src/main/java/examples/MySQLClientExamples.java

@@ -311,6 +311,32 @@ public void numericExample(Row row) {
     }
   }
 
+  enum Color {
+    red
+  }
+
+  public void enumeratedType01Example(SqlClient client) {
+    client
+      .preparedQuery("INSERT INTO colors VALUES (?)")
+      .execute(Tuple.of(Color.red),  res -> {
+        // ...
+      });
+  }
+
+  public void enumeratedType02Example(SqlClient client) {
+    client
+      .preparedQuery("SELECT color FROM colors")
+      .execute()
+      .onComplete(res -> {
+      if (res.succeeded()) {
+        RowSet<Row> rows = res.result();
+        for (Row row : rows) {
+          System.out.println(row.get(Color.class, "color"));
+        }
+      }
+    });
+  }
+
   public void geometryExample01(SqlClient client) {
     client
       .query("SELECT ST_AsText(g) FROM geom;")

vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/MySQLRowImpl.java

@@ -88,6 +88,8 @@ public <T> T get(Class<T> type, int position) {
       return type.cast(getMultiPolygon(position));
     } else if (type == GeometryCollection.class) {
       return type.cast(getGeometryCollection(position));
+    } else if (type.isEnum()) {
+      return type.cast(getEnum(type, position));
     } else {
       throw new UnsupportedOperationException("Unsupported type " + type.getName());
     }
@@ -326,6 +328,22 @@ public LocalTime getLocalTime(int pos) {
     }
   }
 
+  private Object getEnum(Class enumType, int position) {
+    Object val = getValue(position);
+    if (val instanceof String) {
+      return Enum.valueOf(enumType, (String) val);
+    } else if (val instanceof Number) {
+      int ordinal = ((Number) val).intValue();
+      if (ordinal >= 0) {
+        Object[] constants = enumType.getEnumConstants();
+        if (ordinal < constants.length) {
+          return constants[ordinal];
+        }
+      }
+    }
+    return null;
+  }
+
   private <T> String buildIllegalAccessMessage(Object value, String columnName, Class<T> clazz) {
     return String.format("Can not retrieve row value[%s] as class[%s], columnName=[%s]", value.toString(), clazz.getName(), columnName);
   }

vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/datatype/DataTypeCodec.java

@@ -183,6 +183,8 @@ public static void encodeBinary(DataType dataType, Object value, Charset charset
         } else if (value == Tuple.JSON_NULL) {
           // we have to make JSON literal null send as a STRING data type
           BufferUtils.writeLengthEncodedString(buffer, "null", charset);
+        } else if (value instanceof Enum) {
+          binaryEncodeText(((Enum<?>)value).name(), buffer, charset);
         } else {
           binaryEncodeText(String.valueOf(value), buffer, charset);
         }

vertx-mysql-client/src/test/java/io/vertx/mysqlclient/data/StringDataTypeTest.java

@@ -21,6 +21,10 @@
 
 @RunWith(VertxUnitRunner.class)
 public class StringDataTypeTest extends MySQLDataTypeTestBase {
+  private enum Size {
+    x_small, small, medium, large, x_large;
+  }
+
   @Test
   public void testBinaryDecodeAll(TestContext ctx) {
     MySQLConnection.connect(vertx, options, ctx.asyncAssertSuccess(conn -> {
@@ -212,20 +216,44 @@ public void testBinaryDecodeLongText(TestContext ctx) {
   }
 
   @Test
-  public void testBinaryEncodeEnum(TestContext ctx) {
+  public void testBinaryEncodeEnumWithString(TestContext ctx) {
     testBinaryEncodeGeneric(ctx, "test_enum", "medium");
   }
 
   @Test
-  public void testTextDecodeEnum(TestContext ctx) {
+  public void testTextDecodeEnumToString(TestContext ctx) {
     testTextDecodeGenericWithTable(ctx, "test_enum", "small");
   }
 
   @Test
-  public void testBinaryDecodeEnum(TestContext ctx) {
+  public void testBinaryDecodeEnumToString(TestContext ctx) {
     testBinaryDecodeGenericWithTable(ctx, "test_enum", "small");
   }
 
+  @Test
+  public void testBinaryEncodeEnumWithJavaEnum(TestContext ctx) {
+    testBinaryEncodeGeneric(ctx, "test_enum", Size.medium, ((row, colName) -> {
+      ctx.assertEquals(Size.medium, row.get(Size.class, colName));
+      ctx.assertEquals(Size.medium, row.get(Size.class, 0));
+    }));
+  }
+
+  @Test
+  public void testTextDecodeEnumToJavaEnum(TestContext ctx) {
+    testTextDecodeGenericWithTable(ctx, "test_enum", ((row, colName) -> {
+      ctx.assertEquals(Size.small, row.get(Size.class, colName));
+      ctx.assertEquals(Size.small, row.get(Size.class, 0));
+    }));
+  }
+
+  @Test
+  public void testBinaryDecodeEnumToJavaEnum(TestContext ctx) {
+    testBinaryDecodeGenericWithTable(ctx, "test_enum", ((row, colName) -> {
+      ctx.assertEquals(Size.small, row.get(Size.class, colName));
+      ctx.assertEquals(Size.small, row.get(Size.class, 0));
+    }));
+  }
+
   @Test
   public void testBinaryEncodeSet(TestContext ctx) {
     testBinaryEncodeGeneric(ctx, "test_set", "a,b,c");