Develop Reference

c# adding row that already belongs to a datatable

I have a datatable DTgraph, that datatable has a column named Campaign. that column could have one of three unique values, which are IVR, City, City2`. So the rows are like this:
I have a datatable has data like this format
........ IVR........
.........IVR........
**.........IVR........**
.........City1......
.........City1......
**.........City1......**
.........City2......
.........City2......
**.........City2......**
I want to take the last row of each unique value for that column, In other words, I want to take the rows that are bold. I did almost everything like this:
var cRows = new Dictionary<string, DataRow>(StringComparer.InvariantCultureIgnoreCase);
foreach (DataRow oRow in DTgraph.Rows)
{
var sKey = oRow["Campaign"].ToString();
if (!cRows.ContainsKey(sKey))
{
cRows.Add(sKey, oRow);
}
else
{
cRows[sKey] = oRow;
}
}
var oNewTable = DTgraph.Clone();
foreach (var oRow in cRows.Values)
{
oNewTable.Rows.Add(oRow);
}
As you see, I put the data in dictionary and transferred the dictionary to a datatable at the end.
My problem is that on this line:
cRows.Add(sKey, oRow);
I get an error:
The row is already belongs to another datatable
Note: I need to solve that exception, I don't need a new way of doing my goal
Note: I was wrong, the exception is on this line
oNewTable.Rows.Add(oRow);

To be honest I don't 100% understand your question, however to fix the exception:
The row is already belongs to another datatable.
Change:
oNewTable.Rows.Add(oRow);
To:
oNewTable.ImportRow(oRow);
Alternatively create a new row and clone the ItemArray.
foreach (var oRow in cRows.Values)
{
var newRow = oNewTable.NewRow();
newRow.ItemArray = oRow.ItemArray.Clone() as object[];
oNewTable.Rows.Add(newRow);
}

Use NewRow() function of the new table and then use oRow.ItemArray property to get values from the source row and copy them the newly created row's ItemArray. An example would be:
Array.Copy(oRow.ItemArray, oNewTable.NewRow().ItemArray, oRow.ItemArray.Length)
However, remember that this would not preserve original values and current state from the source row (which I don't think you're using here anyway). If those things matter, go for ImportRow() solution which preserves source row's state when copying.

Adding List<string> to DataTable

I created a class library and I am trying to add data from a List<string[]> to a DataGridView.
The string is in the format as follows:
"Test, 1^Glucose^10/24/2013 10:00;Test, 2^BUN^10/25/2013 11:00;Test, 3^BUN^10/25/2013 11:00"
I am passing the string from another program. I then an making it into a list and then trying to add it to the DataTable but no such luck. I created the datagridview with four columns.
Selected - Checkbox
Patient Name - String
Order Name - String
Order Date - String
Reason - Combo Box
I am getting an error:
the list is greater than the number of columns.
Note: I can make the string anyway I want before passing to this program so if I need to do something with the string before passing it to the program, please let me know. Is there an easier way?
I just want the data to display and I will work on the rest of it.
Any help would be appreciated.
This is my code:
public partial class RenewOrders : Form
{
public static string strMLMPatientData = string.Empty;
public RenewOrders(string all_patient_data)
{
InitializeComponent();
strMLMPatientData = "Test, 1^Glucose^10/24/2013 10:00;Test, 2^BUN^10/25/2013 11:00;Test, 3^BUN^10/25/2013 11:00"
}
private void RenewOrders_Load(object sender, EventArgs e)
{
this.ConvertStringToList(strMLMPatientData);
}
private void ConvertStringToList(string strMLMPatientData)
{
var patient_list = strMLMPatientData.Split(';').Select(x => x.Split('^')).ToList();
DataTable dtTable = ConvertListToDataTable(patient_list);
dataGridView1.DataSource = dtTable;
}
// Convert to DataTable.
static DataTable ConvertListToDataTable(List<string[]> patient_list)
{
// New table.
DataTable dtTable = new DataTable();
dtTable.Columns.Add("Name", typeof(string));
dtTable.Columns.Add("Order Name", typeof(string));
dtTable.Columns.Add("Order Date/Time", typeof(string));
foreach (var row in patient_list)
{
table.Rows.Add(row);
}
return dtTable;
}
}

First you need to spit the string appropriately to get a list of string arrays. Something like this:
var patient_list = new List<string[]>(strMLMPatientData.Split(';').Select(x => x.Split(',')));
or even better:
var patient_list = strMLMPatientData.Split(';').Select(x => x.Split(',')).ToList();
You need Linq for that, but you get the idea.
Then you need to add columns to your data table. You cant add rows to it when there are no columns..
Try something like this in your function
//add columns appropriately
DataTable table = new DataTable();
table.Columns.Add("Name", typeof(string));
table.Columns.Add("Order", typeof(string));
table.Columns.Add("Date", typeof(string));
foreach (var row in patient_list)
table.Rows.Add(row);
return table;
See an example here. As it stands, your comma separated input string doesnt seem to match your data table column structure. You need to work it out. But I hope you got the idea which way to go.

sorting and updating datatable not producing expected results

EDIT: Solved this myself - obviously won't work as sorting the dataTable doesn't sort the underlying data - created a dataView from the table, works fine.
I have a datatable which I am sorting and then iterating through to remove duplicate values in one column, however the output is not as expected.
Datatable structure:
infoRow["Title"]
infoRow["QuickLink"]
infoRow["Description"]
infoRow["Date"]
infoRow["MonthName"]
I'm sorting like this, which works fine, and produces a table ordered in ascending month order:
dataTable = dataTable.DefaultView.ToTable(true);
dataTable.DefaultView.Sort = "Date asc";
After the sort, I'm using the code below to compare each row to the previous, and if the MonthName value is the same, replaced it with an empty string:
string prevMonthName = "";
foreach (DataRow row in dtEvents.Rows)
{
string strMonthName = row["MonthName"].ToString();
if (strMonthName == prevMonthName)
{
row["MonthName"] = "";
row.AcceptChanges();
}
prevMonthName = strMonthName;
}
So, the problem I'm having is that even when I run the MonthName loop after the sort, it appears to be running against the unsorted data. It's like DefaultView.Sort only affects the rendered output without physically reordering the table, hence the second part of the code doesn't produce the result I need. Should I maybe be using DataView or am I just way off track...

I was actually having a similar, but slightly different problem and your question gave me an idea. As it turns out, your code was incredibly close to what you (and I) need. All you need to do is flip those two lines of sorting code like so:
dataTable.DefaultView.Sort = "Date ASC";
dataTable = dataTable.DefaultView.ToTable(true);
Now, the first line of code sorts the DefaultView. This would be enough for your DataGridView or ComboBox or whatever you're using for display, because they make use of the DefaultView. However, the DataTable, itself, remains unsorted. Therefore, the second line sets the DataTable to look exactly like the sorted DefaultView.
I just noticed your edit at the top which says you've solved it. That 'solution' seems to be more of a workaround. Seeing as how you had the right code but in the wrong order, I figured you would be interested in this answer.

Assuming that dtEvents is referencing the same object as datatable, you could try this:
string prevMonthName = "";
foreach (DataRowView row in dtEvents.DefaultView)
{
string strMonthName = row["MonthName"].ToString();
if (strMonthName == prevMonthName)
{
row["MonthName"] = "";
row.AcceptChanges();
}
prevMonthName = strMonthName;
}

Just for fun I figured out how to do this using Linq to SQL (assuming I had a sql table with your above schema). Since I spent the time figuring it out, I thought I might as well share it.
// Order the table and add an index column
var ordered = MonthTests.OrderBy(mt => mt.Date)
.AsEnumerable()
.Select((mt, index) => new
{
OrderId = index,
Record = mt
});
// Select out what we want
var query = from item in ordered
let prev = ordered.FirstOrDefault (q => q.OrderId == (item.OrderId-1))
select new
{
Title = item.Record.Title,
QuickLink = item.Record.QuickLink,
Date = item.Record.Date,
MonthName = (prev != null && prev.Record.MonthName == item.Record.MonthName) ? "" : item.Record.MonthName
};
Have fun.

how to get rows created with DataTable.NewRow() in C# / ADO.NET 2.0?

Now I use Select and use a criteria which select only new rows. But is there any kind of GetInsertedRows-method. If I remember correctly there is status for each row so naturally one can loop through them all but that's not elegant.
-Cheers -Matti

I like TypeT's answer but it may help to know that you always bind through a DataView to a DataTable and you can set it to filter on the rows state:
myDataSet.myTable.DefaultView.RowStateFilter = DataViewRowState.Added;
You can also create an additional DataView to look at the new or deleted rows, and then those Views won't byte each other:
var addedView = new DataView(myDataSet.myTable);
addedView.RowStateFilter = DataViewRowState.Added;

I came across this issue myself a while ago, however there's no nice way of pulling out the added rows. I've just trawled my repositories for you and found the DataTable implementation I used to use:
public class AdvancedDataTable : DataTable
{
public IEnumerable<DataRow> InsertedRowList
{
get
{
foreach (DataRow row in this.Rows)
{
if (row.RowState == System.Data.DataRowState.Added)
{
yield return row;
}
}
}
}
}
It's still doing an iteration, but it's nicely wrapped as an IEnumerable and you won't have to write the code more than once.

DataTable.DefaultView.Sort Doesn't Sort

I am confused on DataTable.DefaultView.Sort. Here is the segment of the code I want to use it in.
actionLogDT.DefaultView.Sort = "StartDate";
foreach (CustomerService.ActionLogStartEndRow logRow in actionLogDT)
{
// code here
}
The samples I have seen don't use the foreach loop and thus is confusing me on how to process this. It isn't sorting as I thought it should be.
I see that .DefaultView returns a view, and .Table gives a compile error.

actionLogDT.DefaultView.Sort = "StartDate";
actionLogDT = actionLogDT.DefaultView.ToTable();

Sorting the view won't change the sort order of the data in the table, just the order in the view. It should work if you do your foreach on the view instead, casting the row from the DataRowView back to your strongly typed row.
foreach (DataRowView logRowView in actionLogDT.DefaultView)
{
CustomerService.ActionLogStartEndRow logRow = logRowView.Row as CustomerService.ActionLogStartEndRow;
// code here
}

I had to take a slightly different approach. This post was the closest I could find to get my code to work. Here is the working result:
actionLogDT.DefaultView.Sort = "StartDate";
DataView dv = actionLogDT.DefaultView;
foreach (DataRowView logRow in dv) { . . . }
From there I just have to cast the value back into it's proper type.
(string)logRow["Status"].ToString()

foreach (var logRow in actionLogDT.DefaultView.ToDataTable()) { ... }

Additionally, Since it seemed like you wanted to loop through records, you can just loop through the dataRowView objects in the DefaultView.
foreach (DataRowView drv in table.DefaultView)
{
string strValue = drv["ColumnName"].ToString();
// its also worth mentioning that a DataRowView has a Row
strValue = drv.Row["ColumnName"].ToString();
}

Please try this:
actionLogDT.DefaultView.Sort = "["+actionLogDT.Columns[0].ColumnName+"] asc";

Just curious: Why are you using the DataRowView?
i.e.
foreach (DataRow row in actionLogDT.Rows)
{
Console.WriteLine(row["Status"]);
}

If you need a datatable back then you can do something like:
var dv = actionLogDT.DefaultView;
dv.Sort = "StartDate";
actionLogDT = dv.ToTable();

In VB.NET, the code below was the best way for me to invoke the solution. Just copy your origtable to a DataView, and then the dataview can be sorted with a simple .sort command, and then set a new table equal to the sorted view (of your original table). Use the sorted table dt for your processing thereafter.
Dim View1 As DataView = New DataView(origtable)
View1.Sort = "LastName"
Dim dt As DataTable = View1.ToTable