Multiple forms and datagridviews

bwood2020

Hello, I am having problems populating a second DataTable to use as a data source for a second datagridview on another form. The second DataTable is pulling data in from the main datagridview using a query but the second datagridview doesn't populate. Can someone point me in the right direction please? Here is the code I am running: Form1: string Query = ("SELECT DISTINCT product FROM [" + dataGridView1 + "]"); DataTable GetDocs = new DataTable(Query); DataRow NewLine; NewLine = GetDocs.NewRow(); GetDocs.Rows.Add(NewLine); private DataSet Sds; public DataSet GetDocs { get { return Sds; } set { Sds = value; } Form2: InitializeComponent(); GetForm1 = new Form1(); object GD = GetForm1.GetDocs; this.dataGridView1.RowHeadersVisible = false; this.dataGridView2.RowHeadersVisible = false; this.dataGridView3.RowHeadersVisible = false; this.dataGridView4.RowHeadersVisible = false; this.dataGridView1.DataSource = GD; Tahnk you, Brenton

Henry Minute

Did you paste in the code, or type it?

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucumber?" “I want to report a fraud. The government is lying to us all.”

bwood2020

Hi Henry, The code came from a couple of sites but I typed it in and modified to fit my needs.

Henry Minute

OK. I meant, did you paste it into this site, or type it. But ignore that for now. Without trying to follow what your code is trying to do, a couple of things spring out. You have two members with the same name, in the same scope.

DataTable GetDocs = new DataTable(Query);

and

public DataSet GetDocs

Now the compiler should have given you a warning at the very least, unless you have warnings turned off. Did you ignore the warnings? Because as things are the line from Form2 object GD = GetForm1.GetDocs; will return the second of these which doesn't seem to get initialised anywhere. Turn on warning level 4, if it's not already on. Recompile and sort out any warnings.

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucumber?" “I want to report a fraud. The government is lying to us all.”

bwood2020

Sorry, misunderstood you. Yes I did paste it into the message. I checked to see if warnings where turned off and it doesn't seem to be. I clicked on properties in the solution explorer tab and it looks to be ok. Is there another place I can do this? Otherwise, when I run the app it gives no signs of errors or warnings. I thought both the lines of code are needed. The first one is to declare a new DataTable. The second line is to pass the DataTable to the second form. Is this not correct? I did it this way because that is how you helped me with passing the delimiter to different forms in the last posting I have. Is there a difference when passing strings versus objects? Thank you, Brenton

Henry Minute

Lets try to sort this out one bit at a time. In Form1 you have:

private DataSet Sds;
public DataSet GetDocs
{
get
{
return Sds;
}
set
{
Sds = value;
}

Then in Form2 there is:

object GD = GetForm1.GetDocs;

Since the GetDocs property in the first block above is the only public GetDocs on Form1, it must be that one that GD points to. The getter for GetDocs returns Sds. Now I cannot see anywhere on either form where Sds gets assigned to. I could well be wrong, however because of the way you have named the various members, it is very very difficult to follow what is happening. It is recommended (in the Microsoft Style Guide for C#) that where there is a private field with a public accessor (your Sds and its property GetDocs, from the first code block above), the names should be the same but differentiated by case. So can I suggest that you rename those to match that style. First, just to make it easier to work through please use Sds as the name for now, you can change it to whatever you want later. 1. Hover the mouse pointer over the Sds in the line private DataSet Sds; 2. Right-click 3. From the context menu, hover on 'Refactor' and from the sub-menu select 'Rename' 4. A Dialog will pop up with Sds in a textbox, change that to sds (all lower case) and click OK. If all has gone well the code should look like this

private DataSet sds;
public DataSet GetDocs
{
get
{
return sds;
}
set
{
sds = value;
}

Repeat the above 4 steps for the GetDocs from the line public DataSet GetDocs and change it in the textbox to Sds and click OK. Again if all has gone well you should have

private DataSet sds;
public DataSet Sds
{
get
{
return sds;
}
set
{
sds = value;
}

With any luck at all the Refactoring will have taken care of Form2 as well, and the line object GD = GetForm1.GetDocs; on Form2 will have become object GD = GetForm1.Sds;. I am sorry if I have over simplified anything in this post, or explained something you already know how to do. I am not intending to be insulting, just trying to make sure we are on the same wavelength. :) Come back when you are there.

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucu

bwood2020

Hi Henry, I have made the recommended changes. Also, I don't think using DataSet for the GetDocs property was correct so I changed it to DataTable. Here is what I have: Form1

string Query = ("SELECT * FROM [" + dataGridView1 + "]");
DataTable Sds = new DataTable(Query);
DataRow myNewRow;
myNewRow = Sds.NewRow();
Sds.Rows.Add(myNewRow);

private DataTable sds;
public DataTable Sds
{
get
{
return sds;
}
set
{
sds = value;
}
}

Form2

GetForm1 = new Form1();
object GD = GetForm1.Sds;
this.dataGridView1.DataSource = GD;

modified on Monday, May 18, 2009 1:02 PM

Henry Minute · modified on Monday, May 18, 2009 1:02 PM

Hi, have a good weekend? The problem is, that there are still two members with the same name, which could get confusing. However if the compiler doesn't complain, why should I. :) The next problem to tackle is the line string Query = ("SELECT * FROM [" + dataGridView1 + "]"); I don't know if you know how to use breakpoints, the debugger and single stepping, but if you do you will be able to determine that it evaluates to

SELECT * FROM [System.Windows.Forms.DataGridView]

at runtime. Whereas I suspect that you want it to get the data from the table whose name is selected in dataGridView1. Is that correct?

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucumber?" “I want to report a fraud. The government is lying to us all.”

bwood2020

I had a very productive weekend cutting down dead trees in my backyard. Not something I like spending time on but at least it saves me a few bucks. How about you? I didn't use breakpoints to see if the query was working properly but I did throw in a MessageBox.Show(Query) to evaluate the string and it does say "SELECT * FROM [System.Windows.Forms.DataGridView] so I assumed it was correct. What I would like to do is run a query on the dgv in From 1 to populate the dgv on form 2. From there it would populate a new data table and would be used as the data source for the dgv on Form 2. Right now I have it selecting all just to get the dgv on Form 2 to populate. Later the query will include a Select Distinct. Do you think this is a good way to do this or is there a more efficient method to code this? Thank you, Brenton

Henry Minute

bwood2020 wrote:

Right now I have it selecting all just to get the dgv on Form 2 to populate. Later the query will include a Select Distinct. Do you think this is a good way to do this or is there a more efficient method to code this?

This is a valid approach as 'proof of concept', and for now I would leave it like that, then, as you say, refine it later. The problem with SELECT * FROM [System.Windows.Forms.DataGridView] is that System.Windows.Forms.DataGridView is not a table in a database and therefore there is nothing there to SELECT. However even if this worked, the data retrieved is not being assigned to private DataTable sds;, which is where Form2 is looking for its data. This problem can be solved with one simple change Your code

string Query = ("SELECT * FROM [" + dataGridView1 + "]");
DataTable Sds = new DataTable(Query);
DataRow myNewRow;
myNewRow = Sds.NewRow();
Sds.Rows.Add(myNewRow);

Changed code

string Query = ("SELECT * FROM [" + dataGridView1 + "]");
sds = new DataTable(Query); <============= Here is the change, get rid of 'DataTable Sds' and replace it with just 'sds'
DataRow myNewRow;
myNewRow = Sds.NewRow();
Sds.Rows.Add(myNewRow);

That way you would be assigning the results of the query to the field that Form2 is using. However, I do not believe that change will cause Form2s dataGridView1 to populate as there is no data being returned from your query. All that

sds = new DataTable(Query);

does is create a new DataTable with its Name set to "SELECT * FROM [System.Windows.Forms.DataGridView]". That DataTable with the very long name is not attached to anything, it is not part of your database, it is an orphan. Overall the problem is that Query is not being executed. So we need to get a correct string into Query and then get your query to execute and return a result. Can I suggest that you look at look at Executing a Query that returns Rows[^], scroll down till you get to the section Executing SQL Statements that Return Rows Using a Command Object, which is what I think will be the best way for you to do it. For now, where it shows 'SELECT * FROM customer' replace customer with the name of one of your tables (I beli

bwood2020

I am caught up on the connection string and query for this. I should have made this clear in the beginning so I don't waste your time. The data source/s for this application comes in a file (.xls, .txt, and .csv). There is no SQL Server connection to import data (All the data will be pushed to a staging environment once the data has gone through the app). What I would like to do is connect to the original dataTable that is the source for my dgv on Form 1 and use it as the source for the dgv on Form 2. Is the connection possible? If I connect to the file then the query will fail once I add Distinct because not all headers will be the same and could come in all different ways. I take care of this by allowing the user to select a new header. The addition of the dgv on Form 2 is kicked off once a button has been clicked and that is where all of this comes into play. I went to <a href="http://www.connectionstrings.com/"></a> and I could not find anything that connects to a DataTable. It might be because I'm not looking in the correct place or may be overlooking something. Also, I used product as an example and now I see I should not have done that because it does look like I'm trying to query a table in the database. I hope I have not confused you. If I have I apologize in advance. If you need more information about what I'm doing then let me know.

Henry Minute

OK. Theoretically you can access the the DataSource from dgv1 on Form1 simply by using dataGridView1.DataSource, in which case putting this into your original Query, instead of just dataGridView1, might just work. Suck it and see. If not, then if you could post the code that loads the data into dgv1 on Form1, so that I can advise you further. BTW If you are dealing with .csv and .txt files, you might find FileHelpers v2.0 - Delimited (CSV) or Fixed Data Import/Export Framework[^] from here on CP useful. It won't help with the .xls files though.

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucumber?" “I want to report a fraud. The government is lying to us all.”

bwood2020

Good afternoon Henry, I have tried to run the query using datagridview1.DataSource but doesn't seem to be working. Here is the code I run for csv files. Note that this doesn't show the entire method. In this method there are connections for the other file types. <pre> else if (comboBox1.Text == ".csv") { //Get file path from textbox String FilePath; FilePath = textBox1.Text; //Connect to csv file String comString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Path.GetDirectoryName(FilePath) + @";Extended Properties=""Text;HDR=YES;FMT=Delimited;IMEX=1\"""; String strSql = "SELECT * FROM [" + Path.GetFileName(FilePath) + "]"; OleDbConnection conCSV = new OleDbConnection(comString); conCSV.Open(); OleDbCommand dbCommand = new OleDbCommand(strSql, conCSV); OleDbDataAdapter dAdapter = new OleDbDataAdapter(dbCommand); DataTable dFill = new DataTable(); dAdapter.Fill(dFill); &nbs

Henry Minute

Thanks for posting some of your code. From a quick read through, it seems as if there is some redundant code in there. To help in your future development adventures please try this for me. Remove or comment out the following lines (commenting is probably better till you confirm it is OK):

//create new dataTable and add new top row for new headers
DataTable newDataTable = new DataTable();

                          foreach (DataColumn col in dFill.Columns)
                          {
                                try
                                {
                                      newDataTable.Columns.Add(new DataColumn(col.ColumnName));

                                }
                                catch (Exception)
                                {

                                }
                          }
                          foreach (DataRow row in dFill.Rows)
                          {
                                string\[\] rowarr = new string\[dFill.Columns.Count\];

                                for (int k = 0; k &lt; dFill.Columns.Count; k++)
                                {
                                      rowarr\[k\] = row\[k\].ToString();
                                }
                                newDataTable.Rows.Add(rowarr);

                          }


                          DataRow NewRow;
                          NewRow = newDataTable.NewRow();
                          newDataTable.Rows.InsertAt(NewRow, 0);

As I am not sure of the purpose of the last two three lines of code, you might need to keep them, just change newDataTable to dFill then change this row as indicated:

             // bindingSource1.DataSource = newDataTable;
             bindingSource1.DataSource = dFill;

This should give the same results as before. Have a look and let me know, since only you can tell if it is different. What I then need to know is what you need to happen when when the user double-clicks on dataGridView1 (you are still doing it that way aren't you? Tell me if that has changed.). For example, something like "dgv1 has columns for itemName, itemCost and discount (no need to list them all, just enough for me to get an idea what it's about). When dgv1 is double-clicked I want form2 to open and display information abou

bwood2020

You suggestion worked. All seems to be working the same after testing. Thank you for cleaning up the code. Once the data has been loaded into the dgv on Form 1, the user clicks on the dgv and changes the field headers. This helps standardize the file so the ETL package doesn't break. Once the new field headers have been selected, the user will then click a button. Form 2 is then activated and data has been loaded into different dgv's. dgv1 will be populated with Documentation Type data. Dgv2 will be populated with Purpose Type data and so on for dgv3, dgv4... So what it comes down to is that each dgv on Form 2 will be populated from a single field from the dgv source on Form 1. Each dgv on Form 2 will have three columns (the data from source, a drop down to standardize the data from source, and the count of each distinct value). Once the data has been standardized on Form 2 then the data in the dgv on Form 1 needs to be updated. I am open to any suggestions you may have if there is an easier way to do this. The requirements however still recommend I use a second form to provide translations of data.

Henry Minute

The second Form method seems to be as good as any other, from what you have told me. So on that basis. What happens when the user clicks the button, depends on whether there will only ever be one instance of Form2 where the data displayed will change depending on whatever, or whether there will be more than one instance, each one created specifically to display one set of data. If there will only be one Form2, in Form1 add

private Form2 docsForm = null;
private Form2 DocsForm
{
    get
    {
        if (this.docsForm == null)
        {
            this.docsForm = new Form2();
        }

        return docsForm;
    }
}

then whenever Form1 needs to refer to the Form2 instance just use DocsForm (the property name) NOT docsForm (the field name). This property uses what is known as 'Lazy Initialization', you can look it up later. It just means that the thing (Form2 in this case) only gets created when it needs to be. The rest of the time the existing instance is used. I have made it private deliberately. If there will be many instances of Form2 they will be created inside the click handler for the button, so the above will not be needed. The button click handler, just for illustration purposes I have called it btnShowDocs

	private void btnShowDocs\_Click(object sender, EventArgs e)
	{
                    // \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
                    // Only if there are to be many Form2s
                    // \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
		Form2 DocsForm = new Form2();
                    // \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
                   
                    DocsForm.DataKey = this.dataGridView1.CurrentRow.Cells\[0\].Value.ToString();
                    DocsForm.Show();  // or .ShowDialog(), depends on whether need access to Form1 again before Form2 closes 
	}

There has to be some piece of data in Form1.dgv1, that will enable Form2 to decide the correct data to show, purely for illustration I have said that that data is the value of the first column in the selected row of dgv1. But you will have to let me know what that piece of data is. It could be the value of a cell in dgv as above, or the whole row, each cell in the row determining the data for one of the dgvs of Form2. If the trigger data is not in dgv1, then what is it? Then for Form2, something like:

pu

bwood2020

Yes, there will only be one instance of Form 2. I have dragged and dropped a TabControl onto Form 2. Each tab contains a dgv which will be populated with a column from the dgv on Form 1. I have created a method in Form 1 that goes through each cell in row 1 and stores the new headers in an array. if it meets the criteria then it should load the Distinct values of that column into Form 2. Here is the code I have written but don't know if you can use it as it is. But maybe you can... <pre>public void button12_Click(object sender, EventArgs e) { //MappingsForm is the name of Form 2 MappingsForm.Show(); string[] HeaderArray = new string[dataGridView1.ColumnCount]; int n = dataGridView1.ColumnCount; int c = 0; for (c = 0; c < n; c++) { HeaderArray[c] = dataGridView1.Rows[0].Cells[c].Value.ToString(); if(HeaderArray[c] == "DocType") { &nbs

Henry Minute

I have modified my suggestions from the previous post in light of this information, using your member names where I noticed them and some of your code, although I have suggested moving it to MappingsForm rather than having it in Form1. The reason is that in OOP programming, as far as is possible, each object (and a Form is an object) should be responsible for handling its own data and controlling access to that data. For Form1:

        private MappingsForm mappingsForm = null;
        private MappingsForm MappingsForm
        {
            get
            {
                if (this.mappingsForm == null)
                {
                    this.mappingsForm = new MappingsForm();
                }

                return mappingsForm;
            }
        }

    private void btnShowDocs\_Click(object sender, EventArgs e)
    {
            MappingsForm.DataKey = this.dataGridView1.Rows\[0\];
            MappingsForm.Show();
    }

    private void Form1\_FormClosing(object sender, FormClosingEventArgs e)
    {
        if (this.mappingsForm != null)
	{
	    this.mappingsForm.Dispose();
	    this.mappingsForm = null;
	}
    }

For MappingsForm:

public partial class MappingsForm : Form
{
	private bool dataDisplayed = false;

	public MappingsForm()
	{
	    InitializeComponent();
	}

	private void MappingsForm\_Load(object sender, EventArgs e)
	{
                if (this.dataKey != null)
                { 
	        this.LoadData();
                }
	}

	private void LoadData()
	{
	    // this is part of your code, slightly modified
                for (int c = 0; c < this.dataKey.Columns.Count; c++)
                {
                    if(this.dataKey.Cells\[c\].Value.ToString() == "DocType")
                    {
                        //pass data to dgv1
                    }
                    else if (this.dataKey.Cells\[c\].Value.ToString() == "PurposeType") // else here to avoid unnecessary processing
                    {
                        //pass data to dgv2
                    }
                    else if (this.dataKey.Cells\[c\].Value.ToString() == "SomeOtherType") // else here to avoid unnecessary processing
                    {
                        // and so on 
                    }

                    // This could also be written like this, so either have t

bwood2020

Thanks Henry for the short run down of your concerns. I will look into this... I agree with you about renaming the controls as descriptive as possible. As soon as I get this last part I will go back through and rename them. I implemented the code you wrote and I get the error 'System.Windows.Forms.DataGridViewRow' does not contain a definition for 'Columns'. This occurs at 'this.dataKey.Columns.Count' in the for loop on Form 2. I have tried looking this up and I get similar hits but what I have tried doesn't work. Any ideas?

Henry Minute

Oops. :-O I'm having a root round. I'll get back to you.

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucumber?" “I want to report a fraud. The government is lying to us all.”