A Generic SaveAsXML

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A Generic SaveAs(XML)
Paul Donohue
May 8th 2002 Hotel Senator Zürich
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SaveAs(XML)
The Desired Output

• lt?xml version'1.0'?gt
• lttable_namegt
• lttable_name_rowgt
• ltcol_namegtDisplay Valuelt/column_namegt
• ltcol_name code'Data' gtDisplaylt/col_namegt
• lt/table_name_rowgt
• lt/table_namegt

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SaveAs(XML)
Design Guidelines

• The function must be generic
• The function must cater for large datasets
• The function must handle special markup codes
• The function must cater for edit styles

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SaveAs(XML)
Function Overview

• Add the XML declaration
• Add the root element
• Loop through each row in the datawindow
• Loop through each column in the row
• Get the column data
• Format the data
• Add the data as an element
• Save the data to a text file

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SaveAs(XML)
The XML Declaration

• The first line of any XML file
• This is hard coded
• The XML is being built up as a string

ls_add_to_xml_doc "lt?xml version'1.0'?gt"
ls_xml_doc ls_add_to_xml_doc
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SaveAs(XML)
The Root Element

• The root element is the dw update table
• For a read-only dw the word datawindow is used

ls_describe "DataWindow.Table.UpdateTable" ls_dw
_table_name adw_save_me.Describe(ls_describe) IF
ls_dw_table_name "?" THEN ls_dw_table_name
"Datawindow" END IF
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SaveAs(XML)
The Loops

• There are 2 loops
• One for the rows and one for the columns

ll_max_rows adw_save_me.RowCount() ll_max_cols
Long(dw.Object.DataWindow.Column.Count)
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SaveAs(XML)
Get The Column Details

• Find the columns name, data type edit style

dw.Describe("" String(col_idx)
".Name") dw.Describe("" String(col_idx)
".ColType") dw.Describe("" String(col_idx)
".Edit.Style")
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SaveAs(XML)
Get The Data

• Truncate the first 5 characters of the data type
• Call the appropriate GetItem function

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SaveAs(XML)
Format The Data

• For dddw, ddlb radio buttons use the display
  value
• For edit masks apply the mask

ls_describe Evaluate('LookUpDisplay("
ls_col_name ")', " String(ll_row)
")" ls_display_value dw.Describe(ls_describe) l
s_describe ls_col_name ".EditMask.Mask" ls_edi
t_mask adw_save_me.Describe(ls_describe)
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SaveAs(XML)
Adding An Element

• Column data is added as an element
• dddw, ddlb radio buttons also have an attribute
• Any markup codes are replaced

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SaveAs(XML)
Saving The XML File

• FileWrite can write only 32766 bytes at a time
• Use a loop to write chunks of data

chunk 32765 start 1 stop chunk DO WHILE
FileWrite(file, Mid(xml, start, stop)) gt 0
start chunk stop chunk LOOP
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SaveAs(XML)
Other Information

• Concatenating strings is slow
• BLOBs will improve performance
• ERROR End element was missing the character 'gt
  ' Caused by FileWrite truncating data
• ERROR Invalid at the top level of the document
  Caused by writing a BLOB to the file

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Demonstration
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PowerBuilder 9
XML Support in PB9

• XML Services
• PBDOM DOM in PowerScript
• SaveAs(XML)
• ImportFile(XML!)

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Questions

• If you have any questions about this presentation
  or you would like a copy of the PowerBuilder
  objects please email me or visit my web site.
• Email info_at_pauldonohue.com
• Web www.pauldonohue.com