JSON simple implementation for MSSQL (#1057)

- Use JSON_VALUE
  - Use NVARCHAR type

Signed-off-by: Thibault Meyer <meyer.thibault@gmail.com>

src/main/java/io/ebean/config/dbplatform/sqlserver/SqlServerPlatform.java

@@ -2,11 +2,7 @@ package io.ebean.config.dbplatform.sqlserver;
 
 import io.ebean.PersistBatch;
 import io.ebean.Platform;
-import io.ebean.config.dbplatform.DatabasePlatform;
-import io.ebean.config.dbplatform.DbPlatformType;
-import io.ebean.config.dbplatform.DbType;
-import io.ebean.config.dbplatform.IdType;
-import io.ebean.config.dbplatform.SqlErrorCodes;
+import io.ebean.config.dbplatform.*;
 import io.ebean.dbmigration.ddlgeneration.platform.SqlServerDdl;
 
 import java.sql.Types;
@@ -35,13 +31,13 @@ public class SqlServerPlatform extends DatabasePlatform {
     this.exceptionTranslator =
       new SqlErrorCodes()
         .addAcquireLock("1222")
-        .addDuplicateKey("2601","2627")
-        .addDataIntegrity("544","8114","8115")
+        .addDuplicateKey("2601", "2627")
+        .addDataIntegrity("544", "8114", "8115")
         .build();
 
     this.openQuote = "[";
     this.closeQuote = "]";
-    this.specialLikeCharacters =  new char[] { '%', '_', '[' };
+    this.specialLikeCharacters = new char[]{'%', '_', '['};
     this.likeClause = "like ? COLLATE Latin1_General_BIN";
 
     booleanDbType = Types.INTEGER;
@@ -63,11 +59,13 @@ public class SqlServerPlatform extends DatabasePlatform {
     dbTypeMap.put(DbType.TIME, new DbPlatformType("time"));
     dbTypeMap.put(DbType.TIMESTAMP, new DbPlatformType("datetime2"));
 
+    dbTypeMap.put(DbType.JSON, new DbPlatformType("nvarchar(max)"));
+    dbTypeMap.put(DbType.JSONB, new DbPlatformType("nvarchar(max)"));
+
   }
 
   @Override
   protected void escapeLikeCharacter(char ch, StringBuilder sb) {
     sb.append('[').append(ch).append(']');
   }
-
 }

src/main/java/io/ebeaninternal/server/core/InternalConfiguration.java

@@ -248,19 +248,20 @@ public class InternalConfiguration {
    * Return the JSON expression handler for the given database platform.
    */
   private DbExpressionHandler getDbExpressionHandler(DatabasePlatform databasePlatform) {
-
-    Platform platform = databasePlatform.getPlatform();
-    if (platform == Platform.POSTGRES) {
-      return new PostgresJsonExpression();
+    final Platform platform = databasePlatform.getPlatform();
+    switch (platform) {
+      case POSTGRES:
+        return new PostgresJsonExpression();
+      case ORACLE:
+        return new OracleDbExpression();
+      case SQLSERVER:
+        return new SqlServerJsonExpression();
+      default:
+        return new NotSupportedDbExpression();
     }
-    if (platform == Platform.ORACLE) {
-      return new OracleDbExpression();
-    }
-    return new NotSupportedDbExpression();
   }
 
   public JsonContext createJsonContext(SpiEbeanServer server) {
-
     return new DJsonContext(server, jsonFactory, typeManager);
   }
 

src/main/java/io/ebeaninternal/server/core/SqlServerJsonExpression.java

@@ -0,0 +1,28 @@
+package io.ebeaninternal.server.core;
+
+import io.ebeaninternal.api.SpiExpressionRequest;
+import io.ebeaninternal.server.expression.Op;
+
+/**
+ * Microsoft SQL Server JSON. ARRAY expressions not supported.
+ */
+public class SqlServerJsonExpression implements DbExpressionHandler {
+
+  @Override
+  public void json(final SpiExpressionRequest request, final String propName,
+                   final String path, final Op operator, final Object value) {
+    request.append("json_value(").append(propName).append(", '$.").append(path).append("')");
+    request.append(operator.bind());
+  }
+
+  @Override
+  public void arrayContains(final SpiExpressionRequest request, final String propName,
+                            final boolean contains, final Object... values) {
+    throw new RuntimeException("ARRAY expressions not supported on Microsoft SQL Server");
+  }
+
+  @Override
+  public void arrayIsEmpty(final SpiExpressionRequest request, final String propName, final boolean empty) {
+    throw new RuntimeException("ARRAY expressions not supported on Microsoft SQL Server");
+  }
+}