C# - How to pass null value if the Byte Array is not provided?

Question

I am trying to pass null value to image database field if the ImageByteArray is not provided to Parameters.Add as shown here

cmd.Parameters.Add(new SqlParameter("@Img", SqlDbType.Image)).Value =
    DBNull.Value ? null : ImageByteArray;

but I am getting error that says

Cannot implicitly convert type 'System.DBNull' to 'bool'

first is that correct way to do it >

if yes the how to pass null value if the ImageByteArray is not provided ?

i do not know if am right what i want to do is passing null to the parameter if the Byte Array is not provided so I avoid the Procedure or function expects parameter '@img', which was not supplied.

You aren't passing the value. You are trying to treat it as a boolean. You typed someCondition ? value1 : value2. — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Sep 28, 2018 at 13:25
You're passing DBNull.Value to the ternary operator. That only accepts a boolean and DBNull.Value cannot be implicitly converted to a boolean. — Matt Hogan-Jones
– Matt Hogan-Jones, Commented Sep 28, 2018 at 13:25
You probably wanted to write ImageByteArray ?? DBNull.Value instead? — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Sep 28, 2018 at 13:26
i do not know if am right what i want to do is passing null to the parameter if the Byte Array is not provided so I avoid the Procedure or function expects parameter '@img', which was not supplied. — sam
– sam, Commented Sep 28, 2018 at 13:35
How is ImageByteArray declared? How is it passed in? If it's a byte[] can it really be null? Or just zero length? — Matt Hogan-Jones
– Matt Hogan-Jones, Commented Sep 28, 2018 at 13:43

Serdar · Accepted Answer · 2018-09-28 14:45:08Z

2

DBNull.Value ? null : ImageByteArray;

This part is wrong. Because ternary operator needs to be a boolean result to compare. Try the following one;

(object)ImageByteArray ?? DBNull.Value;

If ImageByteArray is null it will assign DBNull.Value to your sql parameter.

edited Sep 28, 2018 at 14:45

answered Sep 28, 2018 at 13:30

Serdar

8076 silver badges12 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

sam Over a year ago

thanks but I got error cannot be applied to operands of type 'byte[]' and 'System.DBNull' and when I removed one ? sing i got missing :

absoluteAquarian Over a year ago

IIRC for this to work, ImageByteArray has to be nullable, i.e. byte?[]

Serdar Over a year ago

@sam can you share your full code? because byte[] is a nullable type and it shouldn't be cause any error. Maybe you might missing something?

Serdar Over a year ago

@sam can you just put (object) before ImageByteArray for now? I will dig in and will reply with a more proper reply

Serdar Over a year ago

@sam it's cmd.Parameters.Add(new SqlParameter("@Img", SqlDbType.Image)).Value = (object)ImageByteArray ?? DBNull.Value right ?

|

Olivier Belanger · Accepted Answer · 2018-09-28 16:01:33Z

2

Here's what I'm using:

command.Parameters.Add("@Img", SqlDbType.VarBinary, ImageByteArray == null ? -1 : 
ImageByteArray.Length).Value = ImageByteArray ?? (object)DBNull.Value;

Basically, when you send your byte array to your database, you need to specify if it is empty or not. Sending -1 for the length means the received array will be empty.

answered Sep 28, 2018 at 16:01

Olivier Belanger

2001 silver badge8 bronze badges

1 Comment

sam Over a year ago

Thanks for sharing your experience

Collectives™ on Stack Overflow

C# - How to pass null value if the Byte Array is not provided?

2 Answers 2

7 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

7 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related