使用 Delphi7 TClientDataSet：是否可以将其 XML 内容以缩进格式保存？

Question

I am using Delphi7 TClientDataSet to read and write XML files for some of my data.

However, when I want to browse this outside the program (double clicking the XML in Windows Explorer) I get the 'An invalid character was found in text content. Error processing resource' - even though the data reads and writes fine from within Delphi.

Is there a way to force TClientDataSet to write its contents in an indented way instead of in one line?

That way I could easily open it into a text editor and find what character will trigger the above error.

Anyway: I find it much clearer for an XML file to be written with CR/LF and indents anyway.

Answer 1

When you uses the TCustomClientDataSet.SaveToFile procedure, you can choose the output format, for default this value is set to dfBinary wich encode the data in a binary format.

 procedure TCustomClientDataSet.SaveToFile(const FileName: string = '';
  Format: TDataPacketFormat = dfBinary);

try changing the Format parameter to dfXML or dfXMLUTF8

ClientDataSet1.SaveToFile('file.xml',dfXML);

if you want format the XML output you can use the FormatXMLData function try this code

uses
 XMLDoc;

Procedure FormatXMLFile(XmlFile:string);
var
   oXml : TXMLDocument;
 begin
   oXml := TXMLDocument.Create(nil);
   try
     oXml.LoadFromFile(XmlFile);
     oXml.XML.Text:=xmlDoc.FormatXMLData(oXml.XML.Text);
     oXml.Active := true;
     oXml.SaveToFile(XmlFile);
   finally
     oXml := nil;
   end;
 end;

finally you code will look like this

 ClientDataSet1.SaveToFile('test.xml',dfXML);
 FormatXMLFile('test.xml');

Answer 2

It's because the proper encoding (like <?xml version="1.0" encoding="UTF-8"?> ) has not be specified in your output file, yet it contains some characters with an incompatible encoding.

As RRUZ mentioned , specifying explicitly the TDataPacketFormat as dfXMLUTF8 when writing the file will most certainly solve the 'Invalid Character' error, as it will write the encoding tag first:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <DATAPACKET Version="2.0">[...]
You can also add the encoding manually at the beginning of the file for already existing files.

As for the readable formatting, some readers can read the raw one-liner and do the formatting for you (browsers like FireFox or Internet Exporer, and XML editors like XMLNotePad )

Answer 3

I modified your code, because I had some problems with UTF-8:

Procedure FormatXMLFile(XmlFile:string);
var
   oXml : TXMLDocument;
   s : utf8String;
begin
   oXml := TXMLDocument.Create(nil);
   try
     oXml.LoadFromFile(XmlFile);
     s :=  oxml.XML.Text;
     s  := StringReplace(s, '><', '>' + #13#10 + '<' , [rfReplaceAll]);
     //oXml.XML.Text:=xmlDoc.FormatXMLData(oxml.XML.Text);
     oxml.XML.Text := s;
     oXml.Active := true;
     oXml.SaveToFile(XmlFile);
   finally
     oXml := nil;
   end;
end;

Answer 4

dfXMLUTF8 use it for UTF

ClientDataSet1.SaveToFile('test.xml',dfXMLUTF8)