Replacing a DateTime.MinValue in a DataGridView

Question

I am working on a name record application and the information is stored in a SQLite database. All columns in the database are TEXT types, except for the date of birth column, which is a DATETIME. The original Access database that I transferred to the SQLite database allowed nulls for the date of birth, so when I copied it over, I set all nulls to DateTime.MinValue.

In my application, the date of birth column is formatted like so:

DataGridViewTextBoxColumn dateOfBirth = new DataGridViewTextBoxColumn();
        dateOfBirth.HeaderText = "DOB";
        dateOfBirth.DataPropertyName = "DateOfBirth";
        dateOfBirth.Width = 75;
        dateOfBirth.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter;
        dateOfBirth.DefaultCellStyle.Format = "MM/dd/yyyy";

My problem is that rows where there is not a date of birth, the database has DateTime.MinValue, which displays in my DataGridView as 01/01/0001.

I am looking for a way to replace the 01/01/0001 with an empty string ("") in my DataGridView.

private void resultsGrid_DateFormatting(object sender, System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
    {
        if(resultsGrid.Columns[e.ColumnIndex].Name.Equals("DateOfBirth"))
        {
            if ((DateTime)(resultsGrid.CurrentRow.Cells["DateOfBirth"].Value) == DateTime.MinValue)
            {
                 // Set cell value to ""
            }
        }
    }

Anyone have an idea how I can replace a DateTime.MinValue in my DataGridView with an empty string? Thanks!

Edit: Casting the cell value with DateTime allows the if statement I have to work, but I am still not able to figure out the coding to replace the MinValues with a blank string.

Solution 1

You just need to cast it to DateTime

if ((DateTime)(resultsGrid.CurrentRow.Cells["DateOfBirth"].Value) == DateTime.MinValue)
            {
                 // Set cell value to ""
            }

Solution 2

I discovered why the DateTime.MinValue was displaying!

This line in the cell formatting section caused the MinValue of "01/01/0001" to display:

dateOfBirth.DefaultCellStyle.Format = "MM/dd/yyyy";

Without this line, the Date of Birth field in my datagridview is left blank.

Barbaros Alp is still correct about what I was trying to do at the time. Thanks everyone!

Solution 3

Use nullabe DateTime format instead of DateTime ("DateTime?") - don't use string.

example:

public DateTime? mydate;

and then:

DGview.Rows.Add(mydate.HasValue ? mydate : null);

Solution 4

While it may be quite straightforward to achieve the transformation you need (see the excellent answers preceding mine), I feel that you should ideally replace all the DateTime.MinValue values in this particular column in the database with NULL. This would correctly represent the actual lack of data in this position. At present your database contains incorrect data and you are trying to post-process the data for display.

Consequently, you would be able to handle the display of data in your GridView using the EmptyDataText or NullDisplayText properties to provide appropriate rendering.

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Comments

[Jared Harley]

I'm brand new to working with SQLite, so I could be wrong, but I thought that a DateTime couldn't be null. If it can, that would be the optimal solution, because you're right - I've actually put incorrect data into my database.

[Jared Harley]

I added your change to my code above, and it does allow my if statement to work, but I still can't figure the code to actually change the cell contents.

[Barbaros Alp]

In the if statement where you put // Set cell value to ""; i guess you need to write this code resultsGrid.CurrentRow.Cells["DateOfBirth"].Value = "" It should do it

[Barbaros Alp]

resultsGrid.CurrentRow.Cells["DateOfBirth"].Value = ""

[Cerebrus]

Unfortunately, I haven't worked with SQLite, and know even less than you might. However, I think it's worth investigating. Take a look at the documentation. Their site tells me that in SQLite 2, everything was typeless. For SQLite3 - sqlite.org/datatype3.html