org.apache.empire.db.DBQuery 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;
import java.sql.Connection;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.empire.commons.ObjectUtils;
import org.apache.empire.commons.Options;
import org.apache.empire.data.DataType;
import org.apache.empire.db.DBCmdParam;
import org.apache.empire.db.exceptions.InvalidKeyException;
import org.apache.empire.db.exceptions.NoPrimaryKeyException;
import org.apache.empire.db.exceptions.QueryNoResultException;
import org.apache.empire.db.exceptions.RecordNotFoundException;
import org.apache.empire.db.exceptions.RecordUpdateFailedException;
import org.apache.empire.db.exceptions.RecordUpdateInvalidException;
import org.apache.empire.db.expr.compare.DBCompareColExpr;
import org.apache.empire.db.expr.compare.DBCompareExpr;
import org.apache.empire.db.expr.join.DBJoinExpr;
import org.apache.empire.exceptions.InvalidArgumentException;
import org.apache.empire.exceptions.ItemNotFoundException;
import org.apache.empire.exceptions.NotImplementedException;
import org.apache.empire.exceptions.NotSupportedException;
import org.w3c.dom.Element;
/**
* This class can be used to wrap a query from a DBCommand and use it like a DBRowSet.
* You may use this class for two purposes:
*
* - In oder to define subqueries simply define a command object with the subquery and wrap it inside a DBQuery.
* Then in a second command object you can reference this Query to join with your other tables and views.
* In order to join other columns with your query use findQueryColumn(DBColumnExpr expr) to get the
* query column object for a given column expression in the original select clause.
* - With a key supplied you can have an updateable query that will update several records at once.
*
*
*/
public class DBQuery extends DBRowSet
{
private final static long serialVersionUID = 1L;
public static class DBQueryColumn extends DBColumn
{
private final static long serialVersionUID = 1L;
protected DBColumnExpr expr;
/**
* Constructs a DBQueryColumn object set the specified parameters to this object.
*
* @param query the DBQuery object
* @param expr the concrete DBColumnExpr object
*/
public DBQueryColumn(DBQuery query, DBColumnExpr expr)
{ // call base
super(query, expr.getName());
// set Expression
this.expr = expr;
}
@Override
public DataType getDataType()
{
return expr.getDataType();
}
@Override
public double getSize()
{
DBColumn column = expr.getUpdateColumn();
if (column==null)
return 0.0;
return column.getSize();
}
@Override
public boolean isReadOnly()
{
DBColumn column = expr.getUpdateColumn();
if (column==null)
return true;
return column.isReadOnly();
}
@Override
public boolean isAutoGenerated()
{
DBColumn column = expr.getUpdateColumn();
if (column==null)
return false;
return column.isAutoGenerated();
}
@Override
public boolean isRequired()
{
DBColumn column = expr.getUpdateColumn();
if (column==null)
return false;
return column.isRequired();
}
@Override
public Object validate(Object value)
{
DBColumn column = expr.getUpdateColumn();
if (column==null)
return value;
return column.validate(value);
}
@Override
public Object getAttribute(String name)
{
if (attributes != null && attributes.contains(name))
return attributes.get(name);
// Otherwise ask expression
DBColumn column = expr.getUpdateColumn();
if (column==null)
return null;
return column.getAttribute(name);
}
@Override
public Options getOptions()
{
if (options != null)
return options;
// Otherwise ask expression
DBColumn column = expr.getUpdateColumn();
if (column==null)
return null;
return column.getOptions();
}
@Override
public Element addXml(Element parent, long flags)
{
return expr.addXml(parent, flags);
}
}
private static AtomicInteger queryCount = new AtomicInteger(0);
protected DBCommandExpr cmdExpr;
protected DBColumn[] keyColumns = null;
protected DBQueryColumn[] queryColumns = null;
protected String alias;
/**
* Constructor initializes the query object.
* Saves the columns and the primary keys of this query.
*
* @param cmd the SQL-Command
* @param keyColumns an array of the primary key columns
*/
public DBQuery(DBCommandExpr cmd, DBColumn[] keyColumns)
{ // Set the column expressions
super(cmd.getDatabase());
this.cmdExpr = cmd;
// Set Query Columns
DBColumnExpr[] exprList = cmd.getSelectExprList();
queryColumns = new DBQueryColumn[exprList.length];
for (int i = 0; i < exprList.length; i++)
{ // Init Columns
columns.add(exprList[i].getUpdateColumn());
queryColumns[i] = new DBQueryColumn(this, exprList[i]);
}
// Set the key Column
this.keyColumns = keyColumns;
// set alias
this.alias = "q" + String.valueOf(queryCount.incrementAndGet());
}
/**
* Constructs a new DBQuery object initialize the query object.
* Save the columns and the primary key of this query.
*
* @param cmd the SQL-Command
* @param keyColumn the primary key column
*/
public DBQuery(DBCommandExpr cmd, DBColumn keyColumn)
{ // Set the column expressions
this(cmd, new DBColumn[] { keyColumn });
}
/**
* Creaes a DBQuery object from a given command object.
*
* @param cmd the command object representing an SQL-Command.
*/
public DBQuery(DBCommandExpr cmd)
{ // Set the column expressions
this(cmd, (DBColumn[]) null);
}
/**
* returns the command from the underlying command expression or throws an exception
* @return the command used for this query
*/
private DBCommand getCommandFromExpression()
{
if (cmdExpr instanceof DBCommand)
return ((DBCommand)cmdExpr);
// not supported
throw new NotSupportedException(this, "getCommand");
}
/**
* returns the underlying command expression
* @return the command used for this query
*/
public DBCommandExpr getCommandExpr()
{
return cmdExpr;
}
/**
* not applicable - returns null
*/
@Override
public String getName()
{
return null;
}
/**
* not applicable - returns null
*/
@Override
public String getAlias()
{
return alias;
}
/**
* Returns whether or not the table supports record updates.
* @return true if the table allows record updates
*/
@Override
public boolean isUpdateable()
{
return (getKeyColumns()!=null);
}
/**
* Gets all columns of this rowset (e.g. for cmd.select()).
*
* @return all columns of this rowset
*/
public DBQueryColumn[] getQueryColumns()
{
return queryColumns;
}
/**
* This function searchs for equal columns given by the
* specified DBColumnExpr object.
*
* @param expr the DBColumnExpr object
* @return the located column (only DBViewColumn onjects)
*/
public DBQueryColumn findQueryColumn(DBColumnExpr expr)
{
for (int i = 0; i < queryColumns.length; i++)
{
if (queryColumns[i].expr.equals(expr))
return queryColumns[i];
}
// not found
return null;
}
/**
* return query key columns
*/
@Override
public DBColumn[] getKeyColumns()
{
return keyColumns;
}
/**
* Returns a array of primary key columns by a specified DBRecord object.
*
* @param record the DBRecord object, contains all fields and the field properties
* @return a array of primary key columns
*/
@Override
public Object[] getRecordKey(DBRecord record)
{
if (record == null || record.getRowSet() != this)
throw new InvalidArgumentException("record", record);
// get Key
return (Object[]) record.getRowSetData();
}
/**
* Adds the select SQL Command of this object to the specified StringBuilder object.
*
* @param buf the SQL-Command
* @param context the current SQL-Command context
*/
@Override
public void addSQL(StringBuilder buf, long context)
{
buf.append("(");
buf.append(cmdExpr.getSelect());
buf.append(")");
// Add Alias
if ((context & CTX_ALIAS) != 0 && alias != null)
{ // append alias
buf.append(" ");
buf.append(alias);
}
}
/**
* Initialize specified DBRecord object with primary key
* columns (the Object[] keyValues).
*
* @param rec the Record object
* @param keyValues an array of the primary key columns
*/
@Override
public void initRecord(DBRecord rec, Object[] keyValues, boolean insert)
{
// Prepare
prepareInitRecord(rec, keyValues, insert);
// Initialize all Fields
Object[] fields = rec.getFields();
for (int i = 0; i < fields.length; i++)
fields[i] = ObjectUtils.NO_VALUE;
// Set primary key values
if (keyValues != null)
{ // search for primary key fields
DBColumn[] keyColumns = getKeyColumns();
for (int i = 0; i < keyColumns.length; i++)
if (columns.contains(keyColumns[i]))
fields[columns.indexOf(keyColumns[i])] = keyValues[i];
}
// Init
completeInitRecord(rec);
}
/**
* Returns an error, because it is not possible to add a record to a query.
*
* @param rec the DBRecord object, contains all fields and the field properties
* @param conn a valid database connection
* @return a not implemented error
*/
@Override
public void createRecord(DBRecord rec, Connection conn)
{
throw new NotImplementedException(this, "createRecord");
}
/**
* Creates a select SQL-Command of the query call the InitRecord method to execute the SQL-Command.
*
* @param rec the DBRecord object, contains all fields and the field properties
* @param key an array of the primary key columns
* @param conn a valid connection to the database.
*/
@Override
public void readRecord(DBRecord rec, Object[] key, Connection conn)
{
if (conn == null || rec == null)
throw new InvalidArgumentException("conn|rec", null);
DBColumn[] keyColumns = getKeyColumns();
if (key == null || keyColumns.length != key.length)
throw new InvalidKeyException(this, key);
// Select
DBCommand cmd = getCommandFromExpression();
for (int i = 0; i < keyColumns.length; i++)
{ // Set key column constraint
Object value = key[i];
if (db.isPreparedStatementsEnabled())
value = cmd.addParam(keyColumns[i], value);
cmd.where(keyColumns[i].is(value));
}
// Read Record
try {
// Read Record
readRecord(rec, cmd, conn);
// Set RowSetData
rec.updateComplete(key.clone());
} catch (QueryNoResultException e) {
// Record not found
throw new RecordNotFoundException(this, key);
}
}
/**
* Updates a query record by creating individual update commands for each table.
*
* @param rec the DBRecord object. contains all fields and the field properties
* @param conn a valid connection to the database.
*/
@Override
public void updateRecord(DBRecord rec, Connection conn)
{
// check updateable
if (isUpdateable()==false)
throw new NotSupportedException(this, "updateRecord");
// check params
if (rec == null)
throw new InvalidArgumentException("record", null);
if (conn == null)
throw new InvalidArgumentException("conn", null);
// Has record been modified?
if (rec.isModified() == false)
return; // Nothing to update
// Must have key Columns
DBColumn[] keyColumns = getKeyColumns();
if (keyColumns==null)
throw new NoPrimaryKeyException(this);
// Get the fields and the flags
Object[] fields = rec.getFields();
// Get all Update Commands
Map updCmds = new HashMap(3);
for (int i = 0; i < columns.size(); i++)
{ // get the table
DBColumn col = columns.get(i);
if (col == null)
continue;
DBRowSet table = col.getRowSet();
DBCommand updCmd = updCmds.get(table);
if (updCmd == null)
{ // Add a new Command
updCmd = db.createCommand();
updCmds.put(table, updCmd);
}
/*
* if (updateTimestampColumns.contains( col ) ) { // Check the update timestamp cmd.set( col.to( DBDatabase.SYSDATE ) ); }
*/
// Set the field Value
boolean modified = rec.wasModified(i);
if (modified == true)
{ // Update a field
if (col.isReadOnly() && log.isDebugEnabled())
log.debug("updateRecord: Read-only column '" + col.getName() + " has been modified!");
// Check the value
col.validate(fields[i]);
// Set
updCmd.set(col.to(fields[i]));
}
}
// the commands
DBCommand cmd = getCommandFromExpression();
Object[] keys = (Object[]) rec.getRowSetData();
DBRowSet table= null;
DBCommand upd = null;
for(Entry entry:updCmds.entrySet())
{
int i = 0;
// Iterate through options
table = entry.getKey();
upd = entry.getValue();
// Is there something to update
if (upd.set == null)
continue; // nothing to do for this table!
// Evaluate Joins
for (i = 0; cmd.joins != null && i < cmd.joins.size(); i++)
{
DBJoinExpr join = cmd.joins.get(i);
DBColumn left = join.getLeft() .getUpdateColumn();
DBColumn right = join.getRight().getUpdateColumn();
if (left.getRowSet()==table && table.isKeyColumn(left))
if (!addJoinRestriction(upd, left, right, keyColumns, rec))
throw new ItemNotFoundException(left.getFullName());
if (right.getRowSet()==table && table.isKeyColumn(right))
if (!addJoinRestriction(upd, right, left, keyColumns, rec))
throw new ItemNotFoundException(right.getFullName());
}
// Evaluate Existing restrictions
for (i = 0; cmd.where != null && i < cmd.where.size(); i++)
{
DBCompareExpr cmp = cmd.where.get(i);
if (cmp instanceof DBCompareColExpr)
{ // Check whether constraint belongs to update table
DBCompareColExpr cmpExpr = (DBCompareColExpr) cmp;
DBColumn col = cmpExpr.getColumnExpr().getUpdateColumn();
if (col!=null && col.getRowSet() == table)
{ // add the constraint
if (cmpExpr.getValue() instanceof DBCmdParam)
{ // Create a new command param
DBColumnExpr colExpr = cmpExpr.getColumnExpr();
DBCmdParam param =(DBCmdParam)cmpExpr.getValue();
DBCmdParam value = upd.addParam(colExpr, param.getValue());
cmp = new DBCompareColExpr(colExpr, cmpExpr.getCmpop(), value);
}
upd.where(cmp);
}
}
else
{ // other constraints are not supported
throw new NotSupportedException(this, "updateRecord with "+cmp.getClass().getName());
}
}
// Add Restrictions
for (i = 0; i < keyColumns.length; i++)
{
if (keyColumns[i].getRowSet() == table)
{ // Set key column constraint
Object value = keys[i];
if (db.isPreparedStatementsEnabled())
value = upd.addParam(keyColumns[i], value);
upd.where(keyColumns[i].is(value));
}
}
// Set Update Timestamp
int timestampIndex = -1;
Object timestampValue = null;
if (table.getTimestampColumn() != null)
{
DBColumn tsColumn = table.getTimestampColumn();
timestampIndex = this.getColumnIndex(tsColumn);
if (timestampIndex>=0)
{ // The timestamp is availabe in the record
timestampValue = db.getUpdateTimestamp(conn);
Object lastTS = fields[timestampIndex];
if (ObjectUtils.isEmpty(lastTS)==false)
{ // set timestamp constraint
if (db.isPreparedStatementsEnabled())
lastTS = upd.addParam(tsColumn, lastTS);
upd.where(tsColumn.is(lastTS));
}
// Set new Timestamp
upd.set(tsColumn.to(timestampValue));
}
else
{ // Timestamp columns has not been provided with the record
upd.set(tsColumn.to(DBDatabase.SYSDATE));
}
}
// Execute SQL
int affected = db.executeSQL(upd.getUpdate(), upd.getParamValues(), conn);
if (affected <= 0)
{ // Error
if (affected == 0)
{ // Record not found
throw new RecordUpdateFailedException(this, keys);
}
// Rollback
db.rollback(conn);
return;
}
else if (affected > 1)
{ // More than one record
throw new RecordUpdateInvalidException(this, keys);
}
else
{ // success
log.info("Record for table '" + table.getName() + " sucessfully updated!");
}
// Correct Timestamp
if (timestampIndex >= 0)
{ // Set the correct Timestamp
fields[timestampIndex] = timestampValue;
}
}
// success
rec.updateComplete(keys);
}
/**
* Adds join restrictions to the supplied command object.
*/
protected boolean addJoinRestriction(DBCommand upd, DBColumn updCol, DBColumn keyCol, DBColumn[] keyColumns, DBRecord rec)
{ // Find key for foreign field
Object rowsetData = rec.getRowSetData();
for (int i = 0; i < keyColumns.length; i++)
if (keyColumns[i]==keyCol && rowsetData!=null)
{ // Set Field from Key
upd.where(updCol.is(((Object[]) rowsetData)[i]));
return true;
}
// Not found, what about the record
int index = this.getColumnIndex(updCol);
if (index<0)
index = this.getColumnIndex(keyCol);
if (index>=0)
{ // Field Found
if (rec.wasModified(index))
return false; // Ooops, Key field has changed
// Set Constraint
upd.where(updCol.is(rec.getValue(index)));
return true;
}
return false;
}
/**
* Deletes a record identified by its primary key from the database.
*
* @param keys array of primary key values
* @param conn a valid database connection
* @return true if the record has been successfully deleted or false otherwise
*/
@Override
public void deleteRecord(Object[] keys, Connection conn)
{
throw new NotImplementedException(this, "deleteRecord()");
}
}