将XML文件解析为clientdataset的访问冲突

Question

下面是将xml文件读入clientdataset的过程。我的代码在我不理解的“ d循环”的第二次迭代中导致访问冲突错误。daynode.childnodes导致消息：访问权限为000000000000时访问0000000000

在第一次迭代中，dayNode.childnodes是指向具有节点的列表（IXMLnodelist）的指针。在第二次迭代中，dayNode跳转到第二天标签。第二个文件中还包含一些子项，但是为什么这会导致错误？

更新：我添加了addTocds和encodeStrToTdate过程。 cd具有以下字段（“ Projectnr”：字符串，“ weeknr”：整数，“ jaar”：整数，“ ma” ...“ zo”：float）看来addTocds过程（定位）中出了点问题，因为如果我将“ ifloc..then”替换为“ if false then”，则每条记录都会添加到cds中。

<?xml version="1.0" standalone="yes"?>
<ROOT>
    <DAY>
        <DATE>12-10-2019</DATE>
        <STATUS > 1 </STATUS>
        <PROJECTS>
            <PROJECT  nr = "190000"> 5</PROJECT>
            <PROJECT  nr = "190001"> 3</PROJECT>
        </PROJECTS>
    </DAY>
    <DAY>
        <DATE>11-10-2019</DATE>
        <STATUS > 1 </STATUS>
        <PROJECTS>
            <PROJECT nr =  "190000"> 3.4 </PROJECT>
            <PROJECT nr = "190001"> 4   </PROJECT>
        </PROJECTS>
    </DAY>
    <DAY>
        <DATE>13-10-2019</DATE>
        <STATUS > 2 </STATUS>
        <PROJECTS>
            <PROJECT nr = "190000"> 6 </PROJECT>
            <PROJECT nr = "190001"> 7 </PROJECT>
        </PROJECTS>
    </DAY>              
</ROOT>

const
  daysOfWeek: array [ 1 .. 7 ] of string = ( 'ma', 'di', 'wo', 'do', 'vr', 'za', 'zo' );

procedure addTocds( cds: Tclientdataset; dag: integer; week: integer; jaar: integer; pn: string; uren: double );
// dag: day of the week
// week: week of the year
  try
     with cds do
     begin
      if not active then Open;
      first;
      if locate('PROJECTNR;WEEKNR;JAAR', varArrayOf( [pn, week, jaar] ), [loCaseInsensitive] ) then
      begin
           Edit;
           FieldByName( daysOfWeek[ dag ] ).asfloat := uren; //floattostr( uren );
           post;
      end
      else
      begin
          cds.first;
          append;
          FieldByName( daysOfWeek[ dag ] ).asfloat := uren; 
          fieldbyname('PROJECTNR').asstring := pn;
          FieldByName('WEEKNR').asinteger := week; 
          FieldByName('JAAR').asinteger := jaar; 
          Post;
       end;
     end;
    except
        on E:exception do
        begin
             outputdebugstring(Pchar(e.message));
        end;
    end;
  end;

// the strTodate routine result in 3-12-1899 in all cases so I made this (temporarily) function
function encodeStrToTdate(xmlstring: string ): TDate;
var
  position :integer;
  daystr, monthstr, yearstr: string;
begin
  position :=pos('-', xmlstring);
  daystr := copy(xmlstring, 1, position-1);
  delete(Xmlstring,1,position);
  position :=pos('-', xmlstring);
  monthstr := copy(xmlstring, 1, position-1);
  delete(Xmlstring,1,position);
  yearstr := xmlstring;
  result := encodedate(strtoint(yearstr), strtoint(monthstr), strtoint(daystr));
end;

 // lees XML en laadt de XML in een TXMLdocument en open het document
procedure TAVIVparseXML.parseXML( XMLdoc: TXMLdocument; cds: Tclientdataset );
  var // XMLdoc : TXMLdocument;
    statusnode, mainnode, dayNode, datenode, projectNode, projectsNode: IXMLnode;
    dayNodes: IXMLnodelist;
    uren: string;
    d,p : integer;
    datestr: string;
    pn: string;
    dateobj : Tdate;
  begin
    try
    mainnode := XMLdoc.DocumentElement; // ROOT
    dayNodes := mainnode.childnodes;
    for d := 0 to mainnode.ChildNodes.Count - 1 do // DAY
    begin
       dayNode := daynodes.nodes[d]; //mainnode.ChildNodes[de]; //.nodes[de];//.get(d); //[ d ]; // DAY
       if (daynode.NodeName = 'DAY') then
       begin
         dateNode := dayNode.childnodes.FindNode('DATE');
         projectsNode := dayNode.childnodes.findNode('PROJECTS');
         statusNode := dayNode.ChildNodes.FindNode('STATUS');
         if(((dateNode <> nil) and (projectsNode <> nil)) and ((statusNode <> nil))) then
         begin
           datestr := dateNode.text;
           dateobj := encodeStrToTDate(datestr);
           if projectsNode <> nil then
           begin
              for p := 0 to projectsNode.childnodes.Count - 1 do //PROJECTS-> PROJECT
              begin
                projectNode := projectsNode.childnodes.nodes[p]; //.get(p);
                pn := projectNode.attributes['nr'];
                uren := Trim(projectNode.text);
                addTocds( cds, dayOfTheweek(dateobj), weekoftheyear(dateobj), yearOf(dateobj), pn,strTofloat(uren));
              end;
           end;
         end;
       end;
    end;
    except// finally
       outputdebugstring(Pchar('error parseXML'));      // freeandnil(XMLdoc);
    end;
  end;
end.

Answer 1

我找到了解决方案，但还不知道为什么这是解决方案。因为我缺乏有关接口的知识。 xmldoc对象应为Ixmldocument类型，而不是TXMLdocument类型。更改之后，一切正常。