How to pass combobox1 items from form1 to combobox2 in form2

Question

1.00/5 (1 vote)

See more:

I have two combobox (combobox1 in form 1 and combobox2 in form2). I need to import an excel file and the combobox1 gets the sheets name. Then in the form2 (I don't want to import the same file another time) i have combobox2 that have also the same sheets name from the combobox1.

I tried this but i got the error of NULLFUNCTION Expression(Additional Information: The object reference is not set to an instance of an object).

What I have tried:

using (OpenFileDialog openFileDialog = new OpenFileDialog() { Filter = "Excel 97-2003 Workbook|*.xls|Excel Workbook|*.xlsx |fichiers Textes (*.txt)|*.txt|fichiers CSV (*.csv)|*.csv|tous les fichiers (*.*)|*.*" })
            {
                if (openFileDialog.ShowDialog() == DialogResult.OK)
                {
                    TextBox_Emplacement.Text = openFileDialog.FileName;
                    using (var stream = File.Open(openFileDialog.FileName, FileMode.Open, FileAccess.Read))
                    {
                        using (IExcelDataReader reader = ExcelReaderFactory.CreateReader(stream))
                        {
                            DataSet result = reader.AsDataSet(new ExcelDataSetConfiguration()
                            {
                                ConfigureDataTable = (_) => new ExcelDataTableConfiguration() { UseHeaderRow = true }
                            });
                            dataTableCollection = result.Tables; 
                            dataTableCollection1 = result.Tables;
                            sheet.Items.Clear();
                            //cp.radDropDownList1.Items.Clear();
                            foreach (DataTable table in dataTableCollection)
                                sheet.Items.Add(table.TableName);//add sheet to combobox

                           Form_Copie cp1 = (Form_Copie)Application.OpenForms["Form_Copie"];
                           foreach (DataTable table in dataTableCollection)
                              cp1.radDropDownList1.Items.Add(table.TableName);//add sheet to combobox

Posted 12-Jan-21 22:55pm

houssem eddine ayari

Updated 13-Jan-21 10:17am

Add a Solution

Comments

Richard Deeming 13-Jan-21 5:08am

REPOST
This is the same question you posted yesterday:
How to save imported excel path in background to avoid importing multiple times with C#[^]

If you want to update your question, click the green "Improve question" link and edit your question. Do not post the update as a new question.

2 solutions

Solution 1

Exactly how depends on the "relationship" between the two forms.
Have a look at these, one of them will fit your circumstances.
The form that creates an instance of another:

C#

MyForm mf = new MyForm();
mf.Show();

Is the "parent", the other form is the "child".
(This doesn't imply any formal MDI relationship)

Transferring information between two forms, Part 1: Parent to Child[^]
Transferring information between two forms, Part 2: Child to Parent[^]
Transferring information between two forms, Part 3: Child to Child[^]

Posted 12-Jan-21 22:59pm

OriginalGriff

Comments

houssem eddine ayari 13-Jan-21 5:29am

@OriginalGriff there is no relationship between my two forms

OriginalGriff 13-Jan-21 5:38am

If they are both in the same app, there is a relationship between them!
Either one creates an instance of the other, or they are both created by a third form, or forms.
If they are in different applications, then that a whole new ball game - and a complicated one!

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Member 15045156 · Accepted Answer · 2021-01-13T10:17:00

C#

<pre>using (OpenFileDialog openFileDialog = new OpenFileDialog() { Filter = "Excel 97-2003 Workbook|*.xls|Excel Workbook|*.xlsx |fichiers Textes (*.txt)|*.txt|fichiers CSV (*.csv)|*.csv|tous les fichiers (*.*)|*.*" })
            {
                if (openFileDialog.ShowDialog() == DialogResult.OK)
                {
                    TextBox_Emplacement.Text = openFileDialog.FileName;
                    using (var stream = File.Open(openFileDialog.FileName, FileMode.Open, FileAccess.Read))
                    {
                        using (IExcelDataReader reader = ExcelReaderFactory.CreateReader(stream))
                        {
                            DataSet result = reader.AsDataSet(new ExcelDataSetConfiguration()
                            {
                                ConfigureDataTable = (_) => new ExcelDataTableConfiguration() { UseHeaderRow = true }
                            });
                            dataTableCollection = result.Tables; 
                            dataTableCollection1 = result.Tables;
                            sheet.Items.Clear();
                            //cp.radDropDownList1.Items.Clear();
                            foreach (DataTable table in dataTableCollection)
                                sheet.Items.Add(table.TableName);//add sheet to combobox

                           Form_Copie cp1 = (Form_Copie)Application.OpenForms["Form_Copie"];
                           foreach (DataTable table in dataTableCollection)
                              cp1.radDropDownList1.Items.Add(table.TableName);//add sheet to combobox