通过多个动态控件运行查询 c# WinForms

Question

I have created a tool which loops around all listed databases and executes a SQL Query one at a time. I've dynamically created the same controls in a new tab when you click on the New Query button, to allow me to run different queries at the same time.

I have an execute button which will execute the selected script. My problem is that it means my query variable will change depending if I execute another Script.

This is how I find my controls

private void findControls()
{
    tp = metroTabControl1.SelectedTab;
    s = ((SplitContainer)tp.Controls["SplitContainer" + tp.Name.ToString()]);
    tc = ((MetroTabControl)s.Panel2.Controls["AllResults" + tp.Name.ToString()]);
    tpResults = ((TabPage)tc.TabPages["Results" + tp.Name.ToString()]);
    tpMessages = ((TabPage)tc.TabPages["Messages" + tp.Name.ToString()]);

    dgvResults = ((DataGridView)tpResults.Controls["dgv" + tp.Name.ToString()]);
    tbMessages = ((MetroTextBox)tpMessages.Controls["Messages" + tp.Name.ToString()]);
    labCount = ((MetroLabel)s.Panel2.Controls["Progress" + tp.Name.ToString()]);
    tbQuery = ((MetroTextBox)s.Panel1.Controls["SQLQueryText" + tp.Name.ToString()]);
}

On the Execution, I create the BackgroundWorker and I set the Query

BackgroundWorker bgwExec = new BackgroundWorker();
bgwExec.WorkerReportsProgress = true;
bgwExec.WorkerSupportsCancellation = true;

bgwExec.DoWork += BgwExec_DoWork;
bgwExec.ProgressChanged += BgwExec_ProgressChanged;
bgwExec.RunWorkerCompleted += BgwExec_RunWorkerCompleted;

findControls();
query = tbQuery.Text;

In the For loop, it'll run the query over all the databases, the issue though is that if I execute another query, then the BackgroundWorker will start running a different query.

for (int i = 0; i < dtDBList.Rows.Count; i++)
{
    if (bgwExec.CancellationPending == true)
    {
        e.Cancel = true;
        return;
    }
    try
    {
        string server = dtDBList.Rows[i]["server"].ToString();
        string database = dtDBList.Rows[i]["db"].ToString();
        dtResults = eq.SelectStatementResults(query, server, database, iuser, ipass, dtResults);
        ds.Tables.Add(dtResults);
        progress += 1;
        bgwExec.ReportProgress(progress);
        sb = eq.sb;

        log.Info("Executed Script on " + database);
        log.Info(query);
    }
    catch (Exception err)
    {
        log.Error("Failed to execute script " + err.Message);
        progress += 1;
        errorCount += 1;
        bgwExec.ReportProgress(progress);
    }
}

Do you know of any way I can get around this?

I've tried using a dictionary, but then I still don't know how I would pull the correct value from the dictionary...

Thanks in advance

Answer 1

You can use the dictionary in this way:

private readonly Dictionary<BackgroundWorker, string> _queries = new Dictionary<BackgroundWorker, string>();

When creating a new BW, add it with its query to the dictionary:

_queries.Add(bgwExec, tbQuery.Text);

On the BW events handlers, convert sender object to BackgroundWorker and use it to retrieve its query from the dictionary, something like this:

if (_queries.TryGetValue((BackgroundWorker)sender, out string query)) {
  // Do what you need with the query
}
else {
  // not in dictionary
}

Don't forget also to remove it from dictionary when not needed anymore so you don't leak it:

_queries.Remove(bgwExec);

A more robust way to do it would be creating a class that encapsulates both BW and query, being responsible for the executing logic, so you use a List of instances of that class instead of a dictionary.