org.apache.empire.db.DBExpr Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
*
* http://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 org.apache.empire.db;
// java
import org.apache.empire.data.DataType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Collection;
import java.util.Date;
import java.util.Set;
/**
* This abstract class is the base class for all database expression classes (e.g. DBAliasExpr or DBCalsExpr)
*
*
*
*/
public abstract class DBExpr extends DBObject
{
private final static long serialVersionUID = 1L;
private static final Logger log = LoggerFactory.getLogger(DBExpr.class);
// SQL Context Flags
public static final long CTX_DEFAULT = 7; // Default: FullyQualified + Value
public static final long CTX_ALL = 15; // All Flags set (except exclusions)
public static final long CTX_NAME = 1; // Unqualified Name
public static final long CTX_FULLNAME = 2; // Fully Qualified Name
public static final long CTX_VALUE = 4; // Value Only
public static final long CTX_ALIAS = 8; // Rename expression
public static final long CTX_NOPARENTHESES = 16; // No Parentheses
/**
* Used to build the SQL command. SQL for this expression must be appended to StringBuilder.
*
* @param buf the string buffer used to build the sql command
* @param context context flag for this SQL-Command (see CTX_??? constants).
*/
public abstract void addSQL(StringBuilder buf, long context);
/**
* Internal function to obtain all DBColumnExpr-objects used by this expression.
*
* @param list list to which all used column expressions must be added
*/
public abstract void addReferencedColumns(Set list);
/**
* Returns the sql representation of a value.
*
* @param dataType the DataType
* @param value an DBExpr object, array or a basis data type(e.g. int, String)
* @param context the context of the DBColumnExpr object
* @param arraySep the separator value
* @return the new SQL-Command
*/
protected String getObjectValue(DataType dataType, Object value, long context, String arraySep)
{
// it's an Object
if (value instanceof DBExpr)
{ // it's an expression
StringBuilder buf = new StringBuilder();
((DBExpr) value).addSQL(buf, context);
return buf.toString();
}
else if (value instanceof Collection)
{
value = ((Collection)value).toArray();
}
// Check whether it is an array
if (value!=null && value.getClass().isArray())
{
StringBuilder buf = new StringBuilder();
// An Array of Objects
Object[] array = (Object[]) value;
for (int i = 0; i < array.length; i++)
{ // Array Separator
if (i > 0 && arraySep != null)
buf.append(arraySep);
// Append Value
buf.append(getObjectValue(dataType, array[i], context, arraySep));
}
return buf.toString();
}
else
{ // Scalar Value from DB
DBDatabaseDriver driver = getDatabase().getDriver();
if (driver==null)
{ // Convert to String
log.warn("No driver set for getting object value. Using default!");
return String.valueOf(value);
}
// Get Value Expression from Driver
return driver.getValueString(value, dataType);
}
}
/**
* Returns the java class type for a given dataType
* @param type the data type
* @return return the java class used for storing values of this dataType
*/
@SuppressWarnings("unchecked")
public static final Class getValueClass(DataType type)
{
switch(type)
{
case AUTOINC:
case INTEGER:
return Long.class;
case TEXT:
case CLOB:
return String.class;
case DATE:
case DATETIME:
return Date.class;
case CHAR:
return Character.class;
case FLOAT:
return Double.class;
case DECIMAL:
return java.math.BigDecimal.class;
case BOOL:
return Boolean.class;
case BLOB:
return byte[].class;
default:
return Object.class;
}
}
}