IliTableBuffer Class Reference

Table class. More...

#include <ilviews/dataccess/tblbuf.h>

Inheritance diagram for IliTableBuffer:

Public Member Functions
IliValue &	at (IlInt colno)
	Returns a value. More...
IliValue &	at (IliName colname)
	Returns a value. More...
const IliValue &	at (IlInt colno) const
	Returns a value. More...
const IliValue &	at (IliName colname) const
	Returns a value. More...
void	clear ()
	Sets all values in the table buffer to the 0 value. More...
IlInt	count () const
	Returns the number of values in the table buffer. More...
IliTable *	getTable () const
	Returns the table from which the table buffer has been obtained. More...
IlBoolean	isModified () const
	Returns IlTrue if a value in the table buffer has been modified. More...
IlBoolean	isNull () const
	Returns IlTrue if all the values in the table buffer are 0. More...
IliValue &	operator[] (IlInt colno)
	Returns a value. More...
const IliValue &	operator[] (IlInt colno) const
	Returns a value. More...
IliValue &	operator[] (IliName colname)
	Returns a value. More...
const IliValue &	operator[] (IliName colname) const
	Returns a value. More...
IlBoolean	rowToBuffer (IlInt rowno)
	Retrieves a row from the underlying table. More...
Public Member Functions inherited from IliRefCounted
IlInt	getRefCount () const
	Returns the reference count of the object. Initially, this property is set to 0. More...
void	lock () const
	Increments the reference count of the object.
void	unLock () const
	Decrements the reference count of the object. More...

Friends
class	IliTable

Additional Inherited Members
Protected Member Functions inherited from IliRefCounted
virtual	~IliRefCounted ()
	This is the virtual destructor of the IliRefCounted class. More...

Detailed Description

Table class.

Library: dataccess

The IliTableBuffer class works in conjunction with the IliTable class. It is required by the users of a table object, to inspect, alter, or insert new rows into the table. An IliTableBuffer object can be obtained using the IliTable::getBuffer() member function. It can then be used to retrieve rows from the table, to update, or insert new rows into the table. When it is no longer required, it should be returned to the table using the IliTable::releaseBuffer() member function.

See also

IliName, IliTable, IliValue.

Accessors

Accessors provide a scriptable and uniform way to inspect and modify an object by using its base class methods IlvValueInterface::queryValue(), IlvValueInterface::queryValues(), IlvValueInterface::changeValue(), IlvValueInterface::changeValues(). This class defines the following accessors:

Data accessors

Name	Type	Equivalent methods
table	Object	getTable()
columnsCount	Int	getTable()->getColumnsCount()

Method accessors

Name	Return type	Equivalent methods
getValue(String colName)	Object	new IliTableBufferValueItf(this, getTable()->getColumnIndex(colName))
getValueAt(Int col)	Object	new IliTableBufferValueItf(this, col)
rowToBuffer(Int row)	Void	rowToBuffer(row)
clear()	Void	clear()
modifyAll()	Void	modifyAll()
isModified()	Boolean	isModified()
isNull()	Boolean	isNull()

You first obtain a table buffer by calling the table's getBuffer() method. Then the table buffer contains value objects, one for each column of the table to which the table buffer belongs. (See IliTableBufferValue class for more information.)

var buffer = table.getBuffer();

These value objects are properties of the table buffer so that they can be accessed using the dot notation.

var valueObjectID =  buffer.ID;
var valueObjectNAME =  buffer.NAME;

Each of these value objects holds:

• a value
• a "modified" state

When you assign explicitly a value, the value object becomes "modified". Conversely, when you call either the clear() or rowToBuffer() methods, all value objects in the table buffer become "not modified".

var rowno = 2;
buffer.rowToBuffer(rowno);
writeln(valueObjectNAME.isModified()); // prints "false"
valueObjectNAME.value = "Jones";
writeln(valueObjectNAME.isModified()); // prints "true"

Once you have set up the values in the table buffer according to your needs, you can call one of the IliTable methods that take a table buffer as a parameter (such as insertRow(), appendRow() or updateRow()).

These methods will consider only the values that are marked as modified. All other values will be considered as unspecified. This feature is important when you work with SQL databases. You do not want the IliTable.updateRow() method to send back to the database server all values in the row. Only the values that must be modified are sent to the database server.

So, the following code updates only column NAME and leaves column ID unchanged:

table.updateRow(rowno, buffer);

Note that a table buffer obtained from one table can be used with any other table if both tables have the same number of columns and corresponding columns have the same data types in both tables. This lets you easily copy rows from one table to another. (See the description of the modifyAll() method for an example.)

Member Function Documentation

at() [1/4]

IliValue& IliTableBuffer::at

(

IlInt

colno

)

Returns a value.

Parameters

colno

The column position.

Returns

A reference to the value positioned at colno.

at() [2/4]

IliValue& IliTableBuffer::at

(

IliName

colname

)

Returns a value.

Parameters

colname

The column name.

Returns

A reference to the value that corresponds to the column named colname.

at() [3/4]

const IliValue& IliTableBuffer::at

(

IlInt

colno

)

const

Returns a value.

Parameters

colno

The column position.

Returns

A constant reference to the value positioned at colno.

at() [4/4]

const IliValue& IliTableBuffer::at

(

IliName

colname

)

const

Returns a value.

Parameters

colname

The column name.

Returns

A constant reference to the value that corresponds to the column named colname.

clear()

void IliTableBuffer::clear

(

)

Sets all values in the table buffer to the 0 value.

In addition, the modified property of the table buffer is cleared.

count()

IlInt IliTableBuffer::count

(

)

const

Returns the number of values in the table buffer.

Each of these values corresponds to a column in the underlying table.

Returns

The count.

getTable()

IliTable* IliTableBuffer::getTable

(

)

const

Returns the table from which the table buffer has been obtained.

Returns

The table.

isModified()

IlBoolean IliTableBuffer::isModified

(

)

const

Returns IlTrue if a value in the table buffer has been modified.

Returns

IlTrue if a value in the table buffer has been modified since the last time either of the clear() or rowToBuffer() member functions was called.

isNull()

IlBoolean IliTableBuffer::isNull

(

)

const

Returns IlTrue if all the values in the table buffer are 0.

Returns

IlTrue if all the values in the table buffer are 0.

operator[]() [1/4]

IliValue& IliTableBuffer::operator[]

(

IlInt

colno

)

Returns a value.

Parameters

colno

The column position.

Returns

A reference to the value positioned at colno.

operator[]() [2/4]

const IliValue& IliTableBuffer::operator[]

(

IlInt

colno

)

const

Returns a value.

Parameters

colno

The column position.

Returns

A constant reference to the value positioned at colno.

operator[]() [3/4]

IliValue& IliTableBuffer::operator[]

(

IliName

colname

)

Returns a value.

Parameters

colname

The column name.

Returns

A reference to the value corresponding to the column named colname.

operator[]() [4/4]

const IliValue& IliTableBuffer::operator[]

(

IliName

colname

)

const

Returns a value.

Parameters

colname

The column name.

Returns

A constant reference to the value corresponding to the column named colname.

rowToBuffer()

IlBoolean IliTableBuffer::rowToBuffer

(

IlInt

rowno

)

Retrieves a row from the underlying table.

After this member function has been called, each value in the table buffer is the same as its corresponding value in the designated row. In addition, the modified property of the table buffer is cleared.

Parameters

rowno

The row position.

Returns

IlTrue if successful.