scone.netobjects
Class DBTableAdapter

java.lang.Object
  scone.netobjects.DBTableAdapter

public class DBTableAdapter
extends java.lang.Object

stores the database meta information about a TableRecord.
i.e. it knows how to map a TableRecord obect to and from a database. Database fields are seperated into three cases:

• The generated key (autoincrement)
• The composed key (may consist of more than one field)
• The normal fields

DBTableAdapter knows the name, type and default value of each field.

Author:

Harald Weinreich, Volkert Buchmann

Field Summary

protected int	autoincrementLine
static int	BLOB Column type in database is Blob: quote values
protected java.sql.Connection	con
static java.lang.String	COPYRIGHT
protected static java.lang.String	dbURI
protected static java.lang.String	driverName
static int	FIELD Ordinary field
protected int	fieldCount Number of fields per record
protected java.lang.String[]	fieldDefaults Array with default values of fields
protected java.lang.String[]	fieldNames Array of field names
protected int[]	fieldTypes Array of field types: STRING, NUMBER, BLOB
static int	GENERATED Generated Key: AUTO_INCREMENT
protected int	generatedKey The generated key, used if database is not available (con==null || useDB==false)
static int	KEY Key value field: Use to select record in database for update operation
protected int	keyNumber
protected int[]	keyTypes
static int	NUMBER Column type in database is Numerical: do not quote values
protected static java.lang.String	password
protected static boolean	requireDb
static int	STRING Column type in database is String: quote values
protected java.lang.String	tableName The name of the database table
protected static boolean	useDb
protected static java.lang.String	userName

Constructor Summary

DBTableAdapter(java.lang.String tableName)
creates a new DBTableAdapter object

Method Summary

void	addField(java.lang.String fieldName, int fieldType, java.lang.String fieldDefault, int keyType) adds a field to the table definition.
void	createInDB(TableRecord set) Creates a record in the database and fills it with key values If a generated key exists, it reads the value from the database.
void	dbCheck(TableRecord set) tries to read from the database an fills the TableRecord if a set exists.
void	dbCreate(TableRecord set) creates a new Set in the database
protected static void	dbError() this method should be called when an SQLException has been caught.
void	dbInit(TableRecord set) tries to find an equivalent set in the database or creates one if it does not exist.
protected static void	dontUseDb() this method should be called when an SQLException has been caught.
static java.lang.String	escape(java.lang.String s) Calls escape(StringBuffer s)
static java.lang.String	escape(java.lang.StringBuffer s) Escape is used to escape characters, that cause problems with mySQL or mm.mysql The following strings are converted: null (0) -> \0 Backspace (8) -> \b New line (10) -> \n CR (13) -> \r Double qoutes " (34) -> \" Single quote ' (39) -> \' Percent % (92) -> \% Underscore _ (95) -> \_ Math brackets { } (123, 124) -> \( \) Pipe | (124) -> \|
protected boolean	fill(TableRecord set, java.sql.ResultSet results) tries to read from the ResultSet into the TableRecord.
static java.sql.Connection	getConnection() returns a new Connection to the database
java.lang.String	getTableName() Returns the name of this table
boolean	getValuesFromDb(TableRecord set) tries to load the values corresponding to the TableRecord from the database.
java.lang.String	getWhereClause(TableRecord set) generates a where clause to find the specified TableRecord in the database.
static void	init() initializes the DB class by parsing scone/config/db.ini
void	init(TableRecord set) initializes a TableRecord object.
protected FieldValueHashTable	initFields(TableRecord set) creates a new FieldValueHashTable with the names and defaults of the fields
static java.sql.ResultSet	queryDb(java.sql.Connection con, java.lang.String tableName, java.lang.String sqlClause) tries to load the values corresponding to the TableRecord from the database.
static int	rowCountDb(java.sql.Connection con, java.lang.String tableName, java.lang.String sqlClause) Tries to get the number of rows in the database to a given query.
static java.lang.String	safeString(java.lang.String unsafe) Ensures that a String is not null
static java.lang.String	unEscape(java.lang.String s)
static java.lang.String	unEscape(java.lang.StringBuffer s) unEscape Strings read from DB to original values
void	updateDB(TableRecord set) writes the values from the TableRecord into the database
static boolean	useDb() returns true, if the database is used, and false if local memory is used instead

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

COPYRIGHT

public static final java.lang.String COPYRIGHT

See Also:

Constant Field Values

STRING

public static final int STRING

Column type in database is String: quote values

See Also:

Constant Field Values

NUMBER

public static final int NUMBER

Column type in database is Numerical: do not quote values

See Also:

Constant Field Values

BLOB

public static final int BLOB

Column type in database is Blob: quote values

See Also:

Constant Field Values

GENERATED

public static final int GENERATED

Generated Key: AUTO_INCREMENT

See Also:

Constant Field Values

KEY

public static final int KEY

Key value field: Use to select record in database for update operation

See Also:

Constant Field Values

FIELD

public static final int FIELD

Ordinary field

See Also:

Constant Field Values

fieldNames

protected java.lang.String[] fieldNames

Array of field names

fieldTypes

protected int[] fieldTypes

Array of field types: STRING, NUMBER, BLOB

fieldDefaults

protected java.lang.String[] fieldDefaults

Array with default values of fields

fieldCount

protected int fieldCount

Number of fields per record

keyTypes

protected int[] keyTypes

keyNumber

protected int keyNumber

autoincrementLine

protected int autoincrementLine

tableName

protected java.lang.String tableName

The name of the database table

con

protected java.sql.Connection con

generatedKey

protected int generatedKey

The generated key, used if database is not available (con==null || useDB==false)

driverName

protected static java.lang.String driverName

dbURI

protected static java.lang.String dbURI

userName

protected static java.lang.String userName

password

protected static java.lang.String password

useDb

protected static boolean useDb

requireDb

protected static boolean requireDb

Constructor Detail

DBTableAdapter

public DBTableAdapter(java.lang.String tableName)

creates a new DBTableAdapter object

Parameters:

tableName - the name of the table

Method Detail

getTableName

public java.lang.String getTableName()

Returns the name of this table

Returns:

table name in Scone database.

addField

public void addField(java.lang.String fieldName,
                     int fieldType,
                     java.lang.String fieldDefault,
                     int keyType)

adds a field to the table definition. This is called by scone.netobjects.Schema

Parameters:

fieldName - the name of the field

fieldType - the type of the field. Legal values are: String, Number

fieldDefault - the default value in String format

keyType - whether the field is part of a key.

initFields

protected FieldValueHashTable initFields(TableRecord set)

creates a new FieldValueHashTable with the names and defaults of the fields

Parameters:

set - the TableRecord

Returns:

the FieldValueHashTable object

init

public void init(TableRecord set)

initializes a TableRecord object.
the fieldValues are created and set to the defaults

Parameters:

set - the TableRecord object

dbInit

public void dbInit(TableRecord set)

tries to find an equivalent set in the database or creates one if it does not exist.
This method will only work correctly if the value of the autoincrement key
or the composed key in the TableRecord object have been set!

Parameters:

set - the TableRecord object

dbCheck

public void dbCheck(TableRecord set)

tries to read from the database an fills the TableRecord if a set exists. Otherwise it sets TableRecord.hasRecordInDB to false.

Parameters:

set - the TableRecord

dbCreate

public void dbCreate(TableRecord set)

creates a new Set in the database

Parameters:

set - the TableRecord

updateDB

public void updateDB(TableRecord set)

writes the values from the TableRecord into the database

Parameters:

set - the TableRecord

getValuesFromDb

public boolean getValuesFromDb(TableRecord set)

tries to load the values corresponding to the TableRecord from the database.

Parameters:

set - the TableRecord

Returns:

true if the method was successfull, false otherwise

queryDb

public static java.sql.ResultSet queryDb(java.sql.Connection con,
                                         java.lang.String tableName,
                                         java.lang.String sqlClause)

tries to load the values corresponding to the TableRecord from the database.

Parameters:

con - A connection to the DB

tableName - The name of the table in the scone database

sqlClause - A where or order by clause for the querey.

Returns:

A Resultset with the found objects

rowCountDb

public static int rowCountDb(java.sql.Connection con,
                             java.lang.String tableName,
                             java.lang.String sqlClause)

Tries to get the number of rows in the database to a given query.

Parameters:

con - A connection to the DB

tableName - The name of the table in the scone database

sqlClause - A where or order by clause for the querey.

Returns:

An integer with the number of found objects. Returns -1 for error.

fill

protected boolean fill(TableRecord set,
                       java.sql.ResultSet results)

tries to read from the ResultSet into the TableRecord.

Parameters:

set - the TableRecord

results - the ResultSet

Returns:

false, if the ResultSet conatined no data, true otherwise

createInDB

public void createInDB(TableRecord set)

Creates a record in the database and fills it with key values If a generated key exists, it reads the value from the database.

Parameters:

set - the TableRecord

getWhereClause

public java.lang.String getWhereClause(TableRecord set)

generates a where clause to find the specified TableRecord in the database.
Will return the autoincrement key, if a value is given, or the composed key otherwise.

Parameters:

set - the TableRecord

Returns:

the where clause corresponding to the TableRecord object

safeString

public static java.lang.String safeString(java.lang.String unsafe)

Ensures that a String is not null

Parameters:

unsafe - the String

Returns:

the same String or an empty String if the argument was null>

escape

public static java.lang.String escape(java.lang.String s)

Calls escape(StringBuffer s)

escape

public static java.lang.String escape(java.lang.StringBuffer s)

Escape is used to escape characters, that cause problems with mySQL or mm.mysql

The following strings are converted:

• null (0) -> \0
• Backspace (8) -> \b
• New line (10) -> \n
• CR (13) -> \r
• Double qoutes " (34) -> \"
• Single quote ' (39) -> \'
• Percent % (92) -> \%
• Underscore _ (95) -> \_
• Math brackets { } (123, 124) -> \( \)
• Pipe | (124) -> \|

unEscape

public static java.lang.String unEscape(java.lang.String s)

unEscape

public static java.lang.String unEscape(java.lang.StringBuffer s)

unEscape Strings read from DB to original values

init

public static void init()

initializes the DB class by parsing scone/config/db.ini

getConnection

public static java.sql.Connection getConnection()

returns a new Connection to the database

dontUseDb

protected static void dontUseDb()

this method should be called when an SQLException has been caught. It disables database access and notifies the user.

dbError

protected static void dbError()

this method should be called when an SQLException has been caught. It disables database access and notifies the user.

useDb

public static boolean useDb()

returns true, if the database is used, and false if local memory is used instead

Returns:

whether the databse is used