Microsoft Reporting: Setting subreport parameters

问题:

How can I set a parameter of a sub-report? I have successfully hooked myself up to the SubreportProcessing event, I can find the correct sub-report through e.ReportPath, and I can add datasources through e.DataSources.Add. But I find no way of adding report parameters??

I have found people suggesting to add them to the master report, but I don't really want to do that, since the master report shouldn't have to be connected to the sub-report at all, other than that it is wrapping the sub-report.

I am using one report as a master template, printing name of the report, page numbers etc. And the subreport is going to be the report itself. And if I could only find a way to set those report parameters of the sub-report I would be good to go...

Clarification: Creating/Defining the parameters is not the problem. The problem is to set their values. I thought the natural thing to do was to do it in the SubreportProcessing event. And the SubreportProcessingEventArgs do in fact have a Parameters property. But it is read only! So how do you use that? How can I set their value?

回答1:

It does work but it sure is persnickety.

First thing I recommend is to develop your reports as .rdl. Much easier to test the reports this way. You can also get the subreport parameters set up and tested as rdl, making sure each parameter of the subreport is also defined as a parameter of the parent report. Once you get the reports - including the subreports - working that way you can rename the .rdl to rdlc and add the rdlc files to your ReportViewer Project. No further changes required. Use the names of the rdl datasources as the data source names in your code to provide data to the report in the SubreportProcessing event handler.

You don't assign values to the passed parameter. The subreport will use them as is. (Sounds like the step you are missing is adding the parameters to the parent report as well as the the subreport as mentioned above.) You can evaluate the parameters and use them as query parameters to get the datasource you will add. You have to think about the datasource like its on an undiscovered dimension for a subreport. You will have to poke around while debugging in the event handler to see what I mean. Some of the values in your application will be readily available, others that you use easily elsewhere will throw object not found exceptions. For example I create a dataset in a instance of a class created on my applications main form. I use the data set throughout my application. In the SubreportProcessing event handler I cannot use the common dataset, so I must create a new instance of the table I need for the report and populate it. In the main report I would be able to access the common dataset. There are other limitations like this. Just have to wade your way through.

Here is the SubreportProcessing event handler from a working VB.NET ReportViewer application. Shows a few different ways to get the datasource for a subreport. subreport1 builds a one row datatable from application business objects, subreport2 provides data the report requires without a parameter, subreport3 is lie subreport2 but evaluates one of the parameters passed to the subreport for use in date value required by the query that creates the ReportDataSource.

    Public Sub SubreportProcessingEventHandler(ByVal sender As Object, _
                                               ByVal e As SubreportProcessingEventArgs)
    Select Case e.ReportPath
        Case "subreport1"
            Dim tbl As DataTable = New DataTable("TableName")
            Dim Status As DataColumn = New DataColumn
            Status.DataType = System.Type.GetType("System.String")
            Status.ColumnName = "Status"
            tbl.Columns.Add(Status)
            Dim Account As DataColumn = New DataColumn
            Account.DataType = System.Type.GetType("System.String")
            Account.ColumnName = "Account"
            tbl.Columns.Add(Account)
            Dim rw As DataRow = tbl.NewRow()
            rw("Status") = core.GetStatus
            rw("Account") = core.Account
            tbl.Rows.Add(rw)
            e.DataSources.Add(New ReportDataSource("ReportDatasourceName", tbl))
        Case "subreport2"
            core.DAL.cnStr = My.Settings.cnStr
            core.DAL.LoadSchedule()
            e.DataSources.Add(New ReportDataSource("ScheduledTasks", _
                                                   My.Forms.Mother.DAL.dsSQLCfg.tSchedule))
        Case "subreport3"
            core.DAL.cnStr = My.Settings.cnStr
            Dim dt As DataTable = core.DAL.GetNodesForDateRange(DateAdd("d", _
                                                                          -1 * CInt(e.Parameters("NumberOfDays").Values(0)), _
                                                                          Today), _
                                                                  Now)
            e.DataSources.Add(New ReportDataSource("Summary", dt))
    End Select
End Sub

回答2:

Recently I had the same problem and with all the search I didn't find anything helpful but finally I came to a solution for this.

I created a class having all the parameteres in the subreport as it's properties(we can call it a DTO)

public class MyDto
{
    public string EmployeeFirstName{get; set;}
    public string EmployeeLastName{get; set;}
    // and so on
}

Then used a list of this type as another datasource in the main report and then in 'Subreport properties' added a parameter for each parameter in the actual subreport and chose the corresponding fields from the datasource as their values.

then when loading the report convert the input(list of Employees) to a list of MyDto and set it as the reports's datasource :

private void LoadReport(List<Employee> employees)
{
    reportviewerMain.ProcessingMode = ProcessingMode.Local;
    reportviewerMain.LocalReport.ReportPath = Application.StartupPath + "\\Reports\\PayChecksReport.rdlc";

    List<MyDto> employeesDataSource = employees.ConvertAll<MyDto>(emp => new MyDto { EmployeeFirstName = emp.FirstName, EmployeeLastName = emp.LastName}).ToList();
    reportviewerMain.LocalReport.DataSources.Add(new ReportDataSource("EmployeesDataSet", employeesDataSource));

    Organization myOrganization = new OranizationFacade().GetOrganizationInfo();
    reportviewerMain.LocalReport.SetParameters(new ReportParameter("OrganizationName", myOrganization.Name));

    this.reportviewerMain.RefreshReport();
}

And...

It did the trick for me :) I hope it helps somebody.

回答3:

I had a similar problem in that I needed to pass a Properties.Settings.... value to prepend to the path in the database. To do this I had to set a property in the main report and use that property to set the second property in the subreport. Setting the main property then in turn sets the subreport property. YOU CAN set the main property in code as follows:

Suppose you have a ReportViewer name rv, then we would code:

var rp = new ReportParameter("MainReportParamName", Properties.Settings....);
rv.LocalReport.SetParameters(new ReportParameters[] { rp });

回答4:

I know this is an old question which has been marked as answered, but since I was just searching for this today and I saw that it had been commented on within the last few months I thought I'd throw a follow up answer in.

In order to render the subreport in the context of each record on the main report, you need to declare a SubreportProcessingEventHandler and then inside that handler load the DataSet for each instance of the subreport as it occurs. SubreportProcessingEventArgs has a parameters collection which is passed from the parent report when the event fires.

So if you have configured the subreport parameters on the main report with like named parameters bound to fields on the main report, the values are accessible as the subreport is rendered.

Here is a very good write up that explains far more clearly.

回答5:

You could add them via the xml definition. I use xml to create an entire report based on selected sub-reports and other options. I can paste some code in here come Monday if you would like to look at this as a possible solution.

Edit: You can set values on the sub-report in the XML before you deploy the report. This is not very flexible and I am making the assumption that if you want to prompt for these values, you will most likely need them on the parent report.

If you want to see what the XML looks like, add a sub-report, enter values for it in the sub-report properties > parameters, then do a view code.

<Subreport Name="subreport1">
    <Parameters>
      <Parameter Name="StartDate">
        <Value>=Parameters!StartDate.Value</Value>
      </Parameter>
      <Parameter Name="EndDate">
        <Value>1/1/2009</Value>
      </Parameter>

Instead of using the =Parameters!StartDate.Value I'm guessing you would want to put an actual value like on the EndDate.

回答6:

After looking and looking, I have come to the conclusion that setting the parameters of a sub-report, in code, is not possible. Unless you do something fancy like start editing the xml of the report definition before you load it or something like that.

(But if someone else should know that I am wrong, please do answer, cause I am still very curious to know!)

回答7:

Svish - I'm not sure which side of the plumbing you're having trouble with.

To add parameters to the parent report open it then right click on the subreport and select Properties > Parameters.

You can then define parameter names and assign them a value, e.g.

Parameter Name | Parameter Value
---------------+---------------------
MyParameter    | =Fields!Params.Value

So on this side of the plumbing the parameters get their value from the parent report data source.

To add parameters to a subreport open the subreport and from the toolbar select Report > Report Parameters

Here you define a parameter to receive the parameter from the parent report, e.g.

Name      | myParameter
----------+---------------------
Data Type | String

For what it sounds like you want to do can't you do away with a subreport and just have the one report anyway? The information you're trying to wrap around the report sounds ideal for just including in the headers and footers of the report.