org.apache.empire.db.expr.column.DBValueExpr Maven / Gradle / Ivy
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* 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.expr.column;
import java.util.Set;
import org.apache.empire.commons.ObjectUtils;
import org.apache.empire.commons.StringUtils;
// Java
import org.apache.empire.data.DataType;
import org.apache.empire.db.DBColumn;
import org.apache.empire.db.DBColumnExpr;
import org.apache.empire.db.DBDatabase;
import org.apache.empire.db.DBRowSet;
import org.apache.empire.db.DBSQLBuilder;
import org.apache.empire.xml.XMLUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Element;
/**
* This class is used for declaring constant values in SQL.
*
* There is no need to explicitly create instances of this class.
* Instead use {@link DBDatabase#getValueExpr(String)} or one of it's overloads
*
*
*/
public class DBValueExpr extends DBColumnExpr
{
// *Deprecated* private static final long serialVersionUID = 1L;
private static final Logger log = LoggerFactory.getLogger(DBValueExpr.class);
public final DBDatabase db;
public final DataType type;
protected Object value;
private String name;
/**
* Constructs a new DBValueExpr object.
*
* @param db the database
* @param value the value for this constant
* @param type the data type for this constant
*/
public DBValueExpr(DBDatabase db, Object value, DataType type)
{
this.db = db;
this.type = type;
this.value = value;
}
/**
* return the value associated with this value expression
* @return the current value
*/
public Object getValue()
{
return value;
}
/**
* set the value associated with this value expression
* @param value the value to set
*/
public void setValue(Object value)
{
this.value = value;
this.name = null;
}
/**
* Returns the current DBDatabase object.
*
* @return the current DBDatabase object
*/
@SuppressWarnings("unchecked")
@Override
public final DBDatabase getDatabase()
{
return db;
}
/**
* Returns the data type of the DBColumnExpr object.
*
* @return the data type
*/
@Override
public DataType getDataType()
{
return type;
}
/**
* Returns the EnumType if the value is an Enum
*/
@Override
public Class> getEnumType()
{
if (value!=null && value.getClass().isEnum())
{ @SuppressWarnings("unchecked")
Class> enumType = (Class>)value.getClass();
return enumType;
}
return null;
}
/**
* Returns the column name.
*
* @return the column name
*/
@Override
public String getName()
{
if (name==null)
{ // generate name
String str = String.valueOf(value);
int i = 0;
int l = Math.min(str.length(), 20);
for (boolean valid = true; i='0' && c<='9') || (c>='A' && c<='Z') || (c>='a' && c<='z'));
if (!valid)
break;
}
str = str.substring((str.charAt(0)=='-' ? 1 : 0), i);
if (StringUtils.isNotEmpty(str))
{ // generate from value string
char c = str.charAt(0);
if (c>='0' && c<='9')
str = "N"+str;
name = "VAL_"+str.replace(' ','_').toUpperCase();
}
else
{ // default
name = "VALUE";
}
}
return name;
}
/** this helper function calls the DBColumnExpr.addXML(Element, long) method */
@Override
public Element addXml(Element parent, long flags)
{
// Add a column expression for this function
Element elem = XMLUtil.addElement(parent, "column");
String name = getName();
if (name!=null)
elem.setAttribute("name", getName());
// Add Other Attributes
if (attributes!=null)
attributes.addXml(elem, flags);
// add All Options
if (options!=null)
options.addXml(elem, this.type);
// Done
elem.setAttribute("function", "value");
return elem;
}
/**
* Returns null.
* @return null
*/
@Override
public DBRowSet getRowSet()
{
return null;
}
/**
* Returns null.
* @return null
*/
@Override
public DBColumn getUpdateColumn()
{
return null;
}
/**
* Always returns false since value expressions cannot be an aggregate.
*
* @return false
*/
@Override
public boolean isAggregate()
{
return false;
}
/**
* Returns true if other is equal to this expression
*/
@Override
public boolean equals(Object other)
{
if (other==this)
return true;
// Check Type
if (other instanceof DBValueExpr)
{ // Compare
Object otherValue = ((DBValueExpr)other).value;
// Values must match
return ObjectUtils.compareEqual(value, otherValue);
}
return false;
}
/**
* Creates the SQL-Command.
*
* @param sql the SQL-Command
* @param context the current SQL-Command context
*/
@Override
public void addSQL(DBSQLBuilder sql, long context)
{
if ((context & CTX_VALUE)!=0)
sql.appendValue(getDataType(), value);
else
log.warn("Cannot add SQL for DBValueExpr using context {}", context);
}
/**
* @see org.apache.empire.db.DBExpr#addReferencedColumns(Set)
*/
@Override
public void addReferencedColumns(Set list)
{
// nothing to do!
return;
}
}