uk.co.weft.dbutil
Class ClobColumnDescriptor

java.lang.Object
  uk.co.weft.dbutil.ColumnDescriptor
      uk.co.weft.dbutil.ClobColumnDescriptor

public class ClobColumnDescriptor

extends ColumnDescriptor

CLOBs are large chunks of text which may be stored in or returned by a database. The contents of a CLOB may be too large to handle comfortably in core and consequently it may be handy to store them out to the filesystem; however that will vary from application to application. If a value passed into a ClobColumnDescriptor is a file, the descriptor will ever after store values it gets back from the database in files; otherwise it won't. Warning: there's clearly more thinking to be done here. There may need to be a limit size above which we stop handling these things in core. In any case we have to handle it in core as we're composing the SQL string to send to the database, so it's pretty academic...

Field Summary

static int

MAXSTRINGSIZE the largest string I will return -- bigger than this and I will create a file.

Constructor Summary

ClobColumnDescriptor(java.lang.String n)

Method Summary

protected java.lang.String	format(Context c) what we're going to store in CLOBs is essentially files; and we don't want to store the name of the file, we want to store the content.
protected java.lang.Object	interpret(Context context, java.sql.ResultSet results) Read the result from the database either into a String in the context or into a file in the file system depending on the value of useFile.

Methods inherited from class uk.co.weft.dbutil.ColumnDescriptor

createColumnDescriptor, formatForInsert, formatForMatch, formatForMatch, formatForSelect, formatForUpdate, genKey, quoteValue

Methods inherited from class java.lang.Object

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

Field Detail

MAXSTRINGSIZE

public static int MAXSTRINGSIZE

the largest string I will return -- bigger than this and I will create a file.

Constructor Detail

ClobColumnDescriptor

public ClobColumnDescriptor(java.lang.String n)

Parameters:

n - the name of this coumn

Method Detail

format

protected java.lang.String format(Context c)
                           throws DataFormatException

what we're going to store in CLOBs is essentially files; and we don't want to store the name of the file, we want to store the content. Of course, the value of the name in the context may be neither a File object nor the String name of a file, in which case it's the data. Fun disambiguating that...

Overrides:

format in class ColumnDescriptor

Parameters:

c - a context in which a value for my name may be found.

Throws:

DataFormatException

interpret

protected java.lang.Object interpret(Context context,
                                     java.sql.ResultSet results)
                              throws DataFormatException

Read the result from the database either into a String in the context or into a file in the file system depending on the value of useFile. TODO: need to find a way of recycling these files, otherwise the file system will silt up.

Overrides:

interpret in class ColumnDescriptor

Parameters:

context - the service context

results - the results to interpret

Returns:

a file object which is a handle on a file containing the data from the field, or else a String.

Throws:

DataFormatException