Checkbox databinding default value null

Question

I am databinding a checkbox to a bindingsource, if i dont click the checkbox it will return a null value to my database.

This is the databinding code:

 checkGehuwd.DataBindings.Add("Checked", PersonenBindingSource, "gehuwd", true,
            DataSourceUpdateMode.OnPropertyChanged);

how do i return a default value of false?

Greetings Andy

Answer 1

You can use data-binding to CheckState property this way:

checkBox1.DataBindings.Add("CheckState", bs, "DataFieldName", true,
    DataSourceUpdateMode.OnPropertyChanged, CheckState.Indeterminate);

This way, when the value of filed in the data source is null, CheckState.Indeterminate will be shown in UI.

Note

• If you want the default value of column be 0 or unchecked, then set the DefaultValue of DataColumn to 0.

• If you want to let the user also set value of the field to null, it's enough to set ThreeState property of CheckBox to true.

Example

dt = new DataTable();
var c1 = dt.Columns.Add("C1", typeof(int));
c1.AllowDBNull = true;

//Uncomment the next statement if you want default value be 0 = unchecked
//c1.DefaultValue = 0;

//Uncomment the next statement if you want to allow the user to set value to null
//checkBox1.ThreeState = true;

var bs = new BindingSource();
bs.DataSource = dt;
checkBox1.DataBindings.Add("CheckState", bs, "C1", true,
    DataSourceUpdateMode.OnPropertyChanged, CheckState.Indeterminate);
this.bindingNavigator1.BindingSource = bs;