removed the concat-operator "||" and replaced with "concat()" (#1489)

* removed the concat-operator "||" and replaced with "concat()"

* using || in postgres

* FIX: Assert-statement

src/main/java/io/ebean/config/dbplatform/DatabasePlatform.java

@@ -64,8 +64,6 @@ public class DatabasePlatform {
    */
   protected String closeQuote = "\"";
 
-  protected String concatOperator = "||";
-
   /**
    * When set to true all db column names and table names use quoted identifiers.
    */
@@ -455,13 +453,6 @@ public class DatabasePlatform {
     return openQuote;
   }
 
-  /**
-   * Return the DB concat operator.
-   */
-  public String getConcatOperator() {
-    return concatOperator;
-  }
-
   /**
    * Return the JDBC type used to store booleans.
    */

src/main/java/io/ebeaninternal/server/expression/InPairsExpression.java

@@ -92,14 +92,12 @@ class InPairsExpression extends AbstractExpression {
       return;
     }
 
-    String concat = request.getDbPlatformHandler().getConcatOperator();
 
-    String concatFormula = "(" + property0 + concat + "'" + separator + "'" + concat + property1;
-    if (suffix != null && !suffix.isEmpty()) {
-      concatFormula += concat + "'" + suffix + "'";
-    }
-    concatFormula += ")";
-    request.append(concatFormula);
+    StringBuilder sb = new StringBuilder();
+
+    request.getDbPlatformHandler().concat(property0, separator, property1, suffix);
+
+    request.append(request.getDbPlatformHandler().concat(property0, separator, property1, suffix));
     request.appendInExpression(not, concatBindValues);
   }
 

src/main/java/io/ebeaninternal/server/expression/platform/BaseDbExpression.java

@@ -8,17 +8,6 @@ import io.ebeaninternal.server.expression.BitwiseOp;
  */
 abstract class BaseDbExpression implements DbExpressionHandler {
 
-  private final String concatOperator;
-
-  BaseDbExpression(String concatOperator) {
-    this.concatOperator = concatOperator;
-  }
-
-  @Override
-  public String getConcatOperator() {
-    return concatOperator;
-  }
-
   @Override
   public void bitwise(SpiExpressionRequest request, String propName, BitwiseOp operator, long flags, String compare, long match) {
 
@@ -57,4 +46,15 @@ abstract class BaseDbExpression implements DbExpressionHandler {
     }
   }
 
+  @Override
+  public String concat(String property0, String separator, String property1, String suffix) {
+    StringBuilder sb = new StringBuilder();
+    sb.append("CONCAT(").append(property0).append(",'").append(separator).append("',").append(property1);
+
+    if (suffix != null && !suffix.isEmpty()) {
+      sb.append(",'").append(suffix).append('\'');
+    }
+    sb.append(')');
+    return sb.toString();
+  }
 }

src/main/java/io/ebeaninternal/server/expression/platform/BasicDbExpression.java

@@ -8,10 +8,6 @@ import io.ebeaninternal.server.expression.Op;
  */
 public class BasicDbExpression extends BaseDbExpression {
 
-  BasicDbExpression(String concatOperator) {
-    super(concatOperator);
-  }
-
   @Override
   public void json(SpiExpressionRequest request, String propName, String path, Op operator, Object value) {
     throw new RuntimeException("JSON expressions only supported on Postgres and Oracle");

src/main/java/io/ebeaninternal/server/expression/platform/DbExpressionHandler.java

@@ -9,11 +9,6 @@ import io.ebeaninternal.server.expression.Op;
  */
 public interface DbExpressionHandler {
 
-  /**
-   * Return the DB concat operator (Usually SQL standard "||").
-   */
-  String getConcatOperator();
-
   /**
    * Write the db platform specific json expression.
    */
@@ -33,4 +28,9 @@ public interface DbExpressionHandler {
    * Add the bitwise expression.
    */
   void bitwise(SpiExpressionRequest request, String propName, BitwiseOp operator, long flags, String compare, long match);
+
+  /**
+   * Performs a "CONCAT" operation for that platform.
+   */
+  String concat(String property0, String separator, String property1, String suffix);
 }

src/main/java/io/ebeaninternal/server/expression/platform/DbExpressionHandlerFactory.java

@@ -12,20 +12,21 @@ public class DbExpressionHandlerFactory {
   public static DbExpressionHandler from(DatabasePlatform databasePlatform) {
 
     Platform platform = databasePlatform.getPlatform();
-    String concatOperator = databasePlatform.getConcatOperator();
     switch (platform) {
       case H2:
-        return new H2DbExpression(concatOperator);
+        return new H2DbExpression();
       case POSTGRES:
-        return new PostgresDbExpression(concatOperator);
+        return new PostgresDbExpression();
       case MYSQL:
-        return new MySqlDbExpression(concatOperator);
+        return new MySqlDbExpression();
       case ORACLE:
-        return new OracleDbExpression(concatOperator);
+        return new OracleDbExpression();
+      case SQLSERVER16:
+      case SQLSERVER17:
       case SQLSERVER:
-        return new SqlServerDbExpression(concatOperator);
+        return new SqlServerDbExpression();
       default:
-        return new BasicDbExpression(concatOperator);
+        return new BasicDbExpression();
     }
   }
 }

src/main/java/io/ebeaninternal/server/expression/platform/H2DbExpression.java

@@ -8,10 +8,6 @@ import io.ebeaninternal.server.expression.BitwiseOp;
  */
 class H2DbExpression extends BasicDbExpression {
 
-  H2DbExpression(String concatOperator) {
-    super(concatOperator);
-  }
-
   @Override
   public void bitwise(SpiExpressionRequest request, String propName, BitwiseOp operator, long flags, String compare, long match) {
 

src/main/java/io/ebeaninternal/server/expression/platform/MySqlDbExpression.java

@@ -5,8 +5,4 @@ package io.ebeaninternal.server.expression.platform;
  */
 class MySqlDbExpression extends BasicDbExpression {
 
-  MySqlDbExpression(String concatOperator) {
-    super(concatOperator);
-  }
-
 }

src/main/java/io/ebeaninternal/server/expression/platform/OracleDbExpression.java

@@ -9,10 +9,6 @@ import io.ebeaninternal.server.expression.Op;
  */
 public class OracleDbExpression extends BaseDbExpression {
 
-  OracleDbExpression(String concatOperator) {
-    super(concatOperator);
-  }
-
   @Override
   public void json(SpiExpressionRequest request, String propName, String path, Op operator, Object value) {
 

src/main/java/io/ebeaninternal/server/expression/platform/PostgresDbExpression.java

@@ -8,10 +8,6 @@ import io.ebeaninternal.server.expression.Op;
  */
 public class PostgresDbExpression extends BaseDbExpression {
 
-  PostgresDbExpression(String concatOperator) {
-    super(concatOperator);
-  }
-
   @Override
   public void json(SpiExpressionRequest request, String propName, String path, Op operator, Object value) {
 
@@ -65,4 +61,16 @@ public class PostgresDbExpression extends BaseDbExpression {
       request.append(" <> 0");
     }
   }
+
+  @Override
+  public String concat(String property0, String separator, String property1, String suffix) {
+    StringBuilder sb = new StringBuilder();
+    sb.append("(").append(property0).append("||'").append(separator).append("'||").append(property1);
+
+    if (suffix != null && !suffix.isEmpty()) {
+      sb.append("||'").append(suffix).append('\'');
+    }
+    sb.append(')');
+    return sb.toString();
+  }
 }

src/main/java/io/ebeaninternal/server/expression/platform/SqlServerDbExpression.java

@@ -8,10 +8,6 @@ import io.ebeaninternal.server.expression.Op;
  */
 public class SqlServerDbExpression extends BaseDbExpression {
 
-  SqlServerDbExpression(String concatOperator) {
-    super(concatOperator);
-  }
-
   @Override
   public void json(final SpiExpressionRequest request, final String propName,
                    final String path, final Op operator, final Object value) {