C# – File does not exist verify if file name exist SaveFileDialog

csavefiledialog

I want to save a file using the SaveFileDialog control. Why does the file need to already exist in order to save it?

This is the code I am using:

string month = dateTimePicker1.Value.Month.ToString();
string year = dateTimePicker1.Value.Year.ToString();
SaveFileDialog saveFileDialog1 = new SaveFileDialog();
saveFileDialog1.InitialDirectory = @"C:\";
saveFileDialog1.Title = "Save Sql Files";
saveFileDialog1.FileName = "MysqlBackup-"+month+"-"+year+".sql";
saveFileDialog1.CheckFileExists = true;
saveFileDialog1.DefaultExt = "Sql";
saveFileDialog1.Filter = "Sql files (*.Sql)|*.Sql";
saveFileDialog1.FilterIndex = 2;
saveFileDialog1.RestoreDirectory = true;
if (saveFileDialog1.ShowDialog() == DialogResult.OK)
    {
    // Here is the error. After typing in the filename, when I click OK it gives me an error stating that the file does not exist.
    }

Best Answer

This line requires that the file exists in the selected folder

saveFileDialog1.CheckFileExists = true;

set it to false and you could exit with OK if the file doesn't exist

CheckFileExists on MSDN

Gets or sets a value indicating whether the dialog box displays a warning if the user specifies a file name that does not exist.

Related Solutions

C# – The name ‘ConfigurationManager’ does not exist in the current context

It's not only necessary to use the namespace System.Configuration. You have also to add the reference to the assembly System.Configuration.dll , by

Right-click on the References / Dependencies
Choose Add Reference
Find and add System.Configuration.

This will work for sure. Also for the NameValueCollection you have to write:

using System.Collections.Specialized;

C# – Implementing INotifyPropertyChanged – does a better way exist

Without using something like postsharp, the minimal version I use uses something like:

public class Data : INotifyPropertyChanged
{
    // boiler-plate
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
    protected bool SetField<T>(ref T field, T value, string propertyName)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }

    // props
    private string name;
    public string Name
    {
        get { return name; }
        set { SetField(ref name, value, "Name"); }
    }
}

Each property is then just something like:

private string name;
public string Name
{
    get { return name; }
    set { SetField(ref name, value, "Name"); }
}

which isn't huge; it can also be used as a base-class if you want. The bool return from SetField tells you if it was a no-op, in case you want to apply other logic.

or even easier with C# 5:

protected bool SetField<T>(ref T field, T value,
    [CallerMemberName] string propertyName = null)
{...}

which can be called like this:

set { SetField(ref name, value); }

with which the compiler will add the "Name" automatically.

C# 6.0 makes the implementation easier:

protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

...and now with C#7:

protected void OnPropertyChanged(string propertyName)
   => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

protected bool SetField<T>(ref T field, T value,[CallerMemberName] string propertyName =  null)
{
    if (EqualityComparer<T>.Default.Equals(field, value)) return false;
    field = value;
    OnPropertyChanged(propertyName);
    return true;
}

private string name;
public string Name
{
    get => name;
    set => SetField(ref name, value);
}

And, with C# 8 and Nullable reference types, it would look like this:

public event PropertyChangedEventHandler? PropertyChanged;

protected void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

protected bool SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = "")
{
    if (EqualityComparer<T>.Default.Equals(field, value)) return false;
    field = value;
    OnPropertyChanged(propertyName);
    return true;
}

private string name;
public string Name
{
    get => name;
    set => SetField(ref name, value);
}

Best Answer

Related Solutions

C# – The name ‘ConfigurationManager’ does not exist in the current context

C# – Implementing INotifyPropertyChanged – does a better way exist

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