Question

我正在使用Embarcadero RAD Studio XE7，C ++ Builder和FastReport 5.我创建了一个非常简单的FastReport，它在表格中添加了一些值并打印出一个总数。我无法得到总和公式的语法正确，因此它不断抛出访问冲突错误。

要在RAD Studio XE7中重现此问题：

打开RAD Studio XE7并转到文件 - ＆gt;新 - ＆gt; VCL Forms Application - C ++ Builder
将名为ClientDataSet1的TClientDataSet组件拖到窗体上。将名为frxReport1的TfrxReport组件拖到窗体上。将名为frxDBDataset1的TfrxDBDataset拖到窗体上。
将名为Button1的TButton拖到窗体上，然后双击它以创建OnClick事件处理程序。

将以下行添加到Button1Click事件处理程序：

// Create a simple dataset.

ClientDataSet1->FieldDefs->Clear();
ClientDataSet1->FieldDefs->Add("ID", ftInteger, 0, false);
ClientDataSet1->FieldDefs->Add("Status", ftString, 10, false);
ClientDataSet1->FieldDefs->Add("Created", ftDate, 0, false);
ClientDataSet1->FieldDefs->Add("Volume", ftInteger, 0, false);

try
{
  ClientDataSet1->CreateDataSet();
}
catch(Exception& e)
{
  ShowMessage("ERROR: '" + e.Message + "'");
  return;
}

ClientDataSet1->Open();
for (int i = 0; i < 10; ++i)
{
  ClientDataSet1->Append();
  ClientDataSet1->FieldByName("ID")->AsInteger = i;
  ClientDataSet1->FieldByName("Status")->AsString = "Code" + String(i);
  ClientDataSet1->FieldByName("Created")->AsDateTime = Now();
  ClientDataSet1->FieldByName("Volume")->AsInteger = Random(1000);

  try
  {
    ClientDataSet1->Post();
  }
  catch(Exception& e)
  {
    ShowMessage("ERROR: '" + e.Message + "'");
    ClientDataSet1->Close();
    return;
  }
}

// Dataset created successfully, now create Fast Report that outputs that dataset

frxReport1->Clear();
frxDBDataset1->DataSet = (TDataSet*)ClientDataSet1;

frxReport1->DataSets->Add(frxDBDataset1);

TfrxDataPage* DataPage = new TfrxDataPage(frxReport1);
DataPage->CreateUniqueName();

TfrxReportPage* Page = new TfrxReportPage(frxReport1);
Page->CreateUniqueName();

// set sizes of fields, paper and orientation to defaults
Page->SetDefaults();
Page->Orientation = poPortrait;

TfrxReportTitle* HeaderBand = new TfrxReportTitle(Page);
HeaderBand->CreateUniqueName();
HeaderBand->Top = 0;
HeaderBand->Height = 20;

TfrxMemoView* Memo = new TfrxMemoView(HeaderBand);
Memo->CreateUniqueName();
Memo->Text = "Generic Report";
Memo->SetBounds(0, 0, 200, 20);

TfrxHeader* ColumnHeaderBand;
ColumnHeaderBand = new TfrxHeader(Page);
ColumnHeaderBand->CreateUniqueName();
ColumnHeaderBand->Top = HeaderBand->Top + HeaderBand->Height;
ColumnHeaderBand->Height = 20;

TfrxMasterData* DataBand = new TfrxMasterData(Page);
DataBand->Name = "DataBand";
DataBand->DataSet = frxDBDataset1;
DataBand->Top = ColumnHeaderBand->Top + ColumnHeaderBand->Height;
DataBand->Height = 20;

TfrxMemoView* mField;
for (int i = 0; i < DataBand->DataSet->FieldsCount(); ++i)
{
  const String fieldname = ClientDataSet1->Fields->Fields[i]->FieldName;

  mField = new TfrxMemoView(ColumnHeaderBand);
  mField->CreateUniqueName();
  mField->SetBounds(i * 100, 0, 100, 20);
  mField->Text = fieldname;
  mField->HAlign = haCenter;

  // Now do the actual data
  mField = new TfrxMemoView(DataBand);
  mField->CreateUniqueName();
  mField->DataSet = DataBand->DataSet;
  mField->DataField = fieldname;
  mField->SetBounds(i * 100, 0, 100, 20);
  mField->HAlign = haRight;
}

// Now do footer band. This will hold the total
TfrxBand* FooterBand = new TfrxFooter(Page);
FooterBand->CreateUniqueName();
FooterBand->Top = DataBand->Top + DataBand->Height;
FooterBand->Height = HeaderBand->Height;

TfrxMemoView* totals = new TfrxMemoView(FooterBand);
totals->Top = 0;
totals->Left = 0;
totals->Height = 20;
totals->Align = baWidth;

bool is_error = false;
try
{
  // ALL OF THESE LINES CAUSE THE ACCESS VIOLATION

  // Create a summation function that displays the volume total
  totals->Text = "Totals: [Sum(<ClientDataSet1.Volume>, MyDataBand, 1)]";
  //totals->Text = "Totals: [Sum(<ClientDataSet1.'volume'>,MyDataBand,1)]";
  //totals->Text = "Totals: [Sum(<ClientDataSet1.\"volume\">,MyDataBand,1)]";
  //totals->Text = "Totals: [Sum(<ClientDataSet1.""volume"">,MyDataBand,1)]";
  //totals->Text = "Totals: [Sum(<ClientDataSet1.''volume''>,MyDataBand,1)]";
  //totals->Text = "Totals: [Sum(<ClientDataSet1.\'volume\'>,MyDataBand,1)]";
}
catch(Exception& e)
{
  ShowMessage("ERROR: '" + e.Message + "'");
  is_error = true;
}

if (!is_error)
{
  frxReport1->ShowReport(true);
}

ClientDataSet1->Close();

ShowMessage("Program complete!");

编译并运行程序。 try块中的代码将引发访问冲突。为什么会这样？创建总和公式的正确语法是什么？

更新

我通过显式设置frxDBDataset1的名称来修改代码：

    frxReport1->Clear();
    frxDBDataset1->DataSet = (TDataSet*)ClientDataSet1;
    frxDBDataset1->Name = "frxDBDataset1"; // line added
    frxReport1->DataSets->Add(frxDBDataset1);

我还将公式行更改为以下内容：

    totals->Text = "Totals: [Sum(<frxDBDataset1.\"Volume\">, DataBand, 1)]";

但我仍然遇到访问冲突。

Answer 1

我能够毫无问题地运行以下链接示例，其中包括我们之前评论过的修改。

https://www.dropbox.com/s/6grmajvoy9ijxfh/SO_test1.7z?dl=0

Answer 2

转到项目 - ＆gt;选项 - ＆gt;包裹 - ＆gt;运行时包。将“与运行时包链接”设置为False。

此选项的默认值对于C ++ Builder为True，对于Delphi为False。这解释了为什么等效代码在Delphi中工作，但在C ++ Builder中不起作用。

FastReport（RAD Studio XE7 C ++ Builder） - 如何创建总和公式？

2 个答案: