Storing an image in a dataset

[EMW]

Hi,

Is it possible to store an image in a dataset?

I've tried this:
Dim col As new DataColumn()
Dim cols As DataColumnCollection
Dim tp As Type
dsFoto.Tables.Clear()
dsFoto.Tables.Add("pmFoto")
cols = dsFoto.Tables("pmFoto").Columns
col = cols.Add("sitenum")
col.Unique = False
col = cols.Add("thumb", System.Type.GetType("system.Byte"))
col.Unique = False
col = cols.Add("Foto", System.Type.GetType("System.byte"))
col.Unique = False

but I get a NULLEXCEPTION error message.

what do I need to do?

rg,
Eric

 

[Cor]

Hi Eric,

I use another method, but I saw yesterday this in another newsgroup.

http://support.microsoft.com/default.aspx?scid=kb;EN-US;308042

This should be easier than the method I was used to, does this not work,
give a sign again, than I paste her the method with the memorystream in,
that works definitly.

If you do not have the thumb than you have to make that, that sample have I
also.

Cor

 

[EMW]

Thanks, but with this you already have a database filled with pictures and
the dataset table is based on that.

I start with nothing, so I have to make the dataset table.
That is were the problem starts.
How do I let the dataset know that the first column is a string, the second
will get a thumbnal (but that is just an image) and the third is the image
itself.

I think the second and third column needs to be set on Byte but how?

rg,
Eric

 

[Cor]

Hi Eric,

I asume this is the one you are looking for

col = cols.Add("thumb", System.Type.GetType("System.Byte[]"))

Cor

 

[Cor]

I forgot to tell this is case sensitive.

 

[EMW]

Yep, that was it. I didn't look at the uppercase letters and didn't know
about those brackets.
Thanks!


rg,
Eric

 

[Jay B. Harlow [MVP - Outlook]]

Eric,
Read the article from Cor again.

Item #6 shows you how to put (replace actually) the image into the database.

Item #7 shows you how to get the image from the database.


As to for the original question:

Your "type" is wrong.

col = cols.Add("thumb", System.Type.GetType("system.Byte"))

You are creating a column that holds a single byte, you need to create a
column that holds an array of bytes, try:

col = cols.Add("thumb", System.Type.GetType("System.Byte[]"))
col = cols.Add("Foto", System.Type.GetType("System.Byte[]"))

Alternatively I normally use:
col = cols.Add("thumb", GetType(System.Byte()))
col = cols.Add("Foto", GetType(System.Byte()))

As GetType(System.Byte()) does compile time checking while,
System.Type.GetType("System.Byte[]") does runtime checking (if you have an
error in the string itself, such as "Sys.Byt[]", you find out at runtime not
compile time).

Hope this helps
Jay

 

[EMW]

Thanks.

I got it working!

rg,
Eric

Eric,
Read the article from Cor again.

Item #6 shows you how to put (replace actually) the image into the database.

Item #7 shows you how to get the image from the database.


As to for the original question:

Your "type" is wrong.

col = cols.Add("thumb", System.Type.GetType("system.Byte"))

You are creating a column that holds a single byte, you need to create a
column that holds an array of bytes, try:

col = cols.Add("thumb", System.Type.GetType("System.Byte[]"))
col = cols.Add("Foto", System.Type.GetType("System.Byte[]"))

Alternatively I normally use:
col = cols.Add("thumb", GetType(System.Byte()))
col = cols.Add("Foto", GetType(System.Byte()))

As GetType(System.Byte()) does compile time checking while,
System.Type.GetType("System.Byte[]") does runtime checking (if you have an
error in the string itself, such as "Sys.Byt[]", you find out at runtime not
compile time).

Hope this helps
Jay

Thanks, but with this you already have a database filled with pictures and
the dataset table is based on that.

I start with nothing, so I have to make the dataset table.
That is were the problem starts.
How do I let the dataset know that the first column is a string, the second
will get a thumbnal (but that is just an image) and the third is the image
itself.

I think the second and third column needs to be set on Byte but how?

rg,
Eric



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