DataView RowFilter doesn't filter the Rows on DataGridView

问题

I have this function button_Search1_Click to search for comments that match keywords, then display these flagged comments in dataGridView_flaggedComments.

Next, if there's any changes on the comboBox_stockIndex, I want the filter to take place i.e. filter the flagged comments in dataGridView_flaggedComments with the Tickers_Ticker_ID of 1. But when I do that, all the comments (regardless flagged or not) belong to Tickers_Ticker_ID of 1 display on my dataGridView_flaggedComments. It should have only display the flagged comments for Tickers_Ticker_ID of 1, not all the comments.

I think there's something wrong with the DataSource but I couldn't figure it out. Any help would be very very much appreciated! Thank you!

(If I did miss any similar questions, kindly point it out. Thank you very much!)

private void button_Search1_Click(object sender, EventArgs e)
{
    commentCount = 0;
    richTextBox_flaggedComments.Clear();
    dataGridView_flaggedComments.Refresh();
    DataTable flaggedcomments = new DataTable("flaggedcomments");
    using (MySqlConnection sqlConn = new MySqlConnection(strProvider))
    {
        using (MySqlDataAdapter da = new MySqlDataAdapter(
        "SELECT Comment_ID, Comments_Date, Author, Title, Comments_Comment, " + 
              " Tickers_Ticker_ID FROM comments ORDER BY Comments_Date ASC", sqlConn))
        {
            da.Fill(flaggedcomments);
        }
    }
    StringBuilder sb = new StringBuilder();
    string[] words = File.ReadAllLines(sourceDirTemp + 
                          comboBox_crimeKeywords.SelectedItem.ToString() + ".txt");
    var query = flaggedcomments.AsEnumerable().Where(r =>
        words.Any(wordOrPhrase => Regex.IsMatch(r.Field<string>("Comments_Comment"),
              @"\b" + Regex.Escape(wordOrPhrase) + @"\b",  RegexOptions.IgnoreCase)));

    dataGridView_flaggedComments.DataSource = query.AsDataView();
}


private void comboBox_stockIndex_SelectedIndexChanged(object sender, EventArgs e)
{
    DataView dv = dataGridView_flaggedComments.DataSource as DataView;
    if (dv == null)
        throw new Exception("Bad Data Source type");
    else
    {
        dv.RowFilter = string.Format("Tickers_Ticker_ID = '1'");
        dataGridView_flaggedComments.DataSource = dv;
    }
}

回答1:

A DataView as such does not hold any data.

When you set the filter you are effectively replacing the orginal filter in your LinqDataView, that is the Where clause, by the new filter, that is by the RowFilter.

You need to concatenate them to create a double condition.

Since your Where clause uses a complex RegEx I think the easiest way will be to re-use it, appending it with the new, simple 'Tickers_Ticker_ID = ' + id condition.

If you don't want to reapply the original filter you may want to store the filtered rows in a temporary Table. Here I have a DataSet DS and first clone the structure of the 1st Table, name the new Table and add it to the DataSet. When appropriate I copy the filtered rows over from the query:

Set up the Temp Table, where you set up you other DB stuff:

DataSet DS;                             // if you don't already have one..
                                        // put it at class level!

DS = new DataSet();                     // ..create it
DataTable DT = DS.Tables[0].Clone();    // the temp table has the sdame structure
DT.TableName = "temp";                  // is called by a name
DS.Tables.Add(DT);                      // and (optionally) added to the DataSet.

When you do the search you load the data into the temp table:

DS.Tables["temp"].Rows.Clear();
query.CopyToDataTable( DS.Tables["temp"], LoadOption.OverwriteChanges);
DGV.DataSource = DS.Tables["temp"]; 

Now you can use it in the combo_filter_SelectedIndexChanged event:

 string id = ddl_filter.Text;
 if (id == "") DGV.DataSource = DS.Tables["temp"];
 else
 {
    DataView dv = new DataView(DS.Tables["temp"])
    dv.RowFilter = string.Format("id = " + id) ;
    DGV.DataSource = dv;
 }

回答2:

Your filtering wrong... try this instead...

  dv.RowFilter = "Tickers_Ticker_ID = 1";

来源：https://stackoverflow.com/questions/26706066/dataview-rowfilter-doesnt-filter-the-rows-on-datagridview