VBA Access - TextBox Value to String

Question

I'm trying to read the value of a text box to a string and check if it's empty:

Dim dataFileName as String

dataFileName = Text0.Value

If dataFileName = "" Then
End If

This crashes with "Invalid use of Null" when making the assignment. How can I do this?

What is "Text0" composed of? Can you show the code where it's obtained/created? — EngJon
– EngJon, Commented Jan 20, 2015 at 12:44

PaulFrancis · Accepted Answer · 2015-01-20 12:50:42Z

1

There are one or many ways to test this.

Here are two ways,

Dim dataFileName
dataFileName = Me.Text0

If IsNull(dataFileName) Then
'Or If Len(dataFileName & vbNullString) = 0 Then
    MsgBox "It is a Variant Type, but is Null"
Else
    MsgBox "It is a Variant Type, but is not Null"
End If

The other way is to declare it as String, but make sure you pass a String not Null

Dim dataFileName As String
dataFileName = Me.Text0 & vbNullString
'Or dataFileName = Nz(Me.Text0, vbNullString)

If Len(dataFileName) = 0 Then
    MsgBox "It is a String Type but is a NullString, but NOT NULL"
Else
    MsgBox "It is a String Type, it is not 'empty' persay."
End If

answered Jan 20, 2015 at 12:50

PaulFrancis

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1 Comment

PaulFrancis Over a year ago

& is the concatenation operator in VBA. So when you concatenate the Null with a NullString, the value is not Null anymore, but is converted to a String of ZERO length.

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