DataImageUrlField in DetailsView

[GaryDean]

(This issue has already been posted by one of our developers (Tina) but I am
reposting
it because it's urgent and I have the MSDN subscription so we are guessing I
may
be more likely to get a response)

I can't get an image to show in a DetailsView. I am trying both an
ImageField and a template field with an image in it with databindings to the
datasource. I know the datasource works because the image shows in the
test. All I get is the RED X.

I have google searched this problem and I have seen it reported several
times but never answered. Is this a bug? Is there a workaround?


here is my DetailsView definition......................
<aspetailsView ID="dvDetails" runat="server" Height="50px"
Width="708px" AutoGenerateRows="False" DataSourceID="dsDetails">
<Fields>
<asp:CheckBoxField DataField="active"
HeaderText="active" SortExpression="active" />
<asp:BoundField DataField="numresumesposted"
HeaderText="numresumesposted" SortExpression="numresumesposted" />
<asp:BoundField DataField="address1"
HeaderText="address1" SortExpression="address1" />
<asp:BoundField DataField="hoursavailable"
HeaderText="hoursavailable" SortExpression="hoursavailable" />
<asp:BoundField DataField="maxhoursperweek"
HeaderText="maxhoursperweek" SortExpression="maxhoursperweek" />
<asp:BoundField DataField="resumetitle"
HeaderText="resumetitle" SortExpression="resumetitle" />
<asp:BoundField DataField="resumefilestring"
HeaderText="resumefilestring" SortExpression="resumefilestring" />
<asp:ImageField AccessibleHeaderText="Photo"
DataImageUrlField="photo">
</asp:ImageField>
<asp:TemplateField>
<ItemTemplate>
<asp:Image ID="Image1" runat="server"
Height="166px" ImageUrl='<%# Eval("photo") %>'
Width="175px" />
</ItemTemplate>
</asp:TemplateField>
</Fields>
</aspetailsView>

thanks,
Gary

 

[Jesse Houwing]

Hello GaryDean,

(This issue has already been posted by one of our developers (Tina)
but I am
reposting
it because it's urgent and I have the MSDN subscription so we are
guessing I
may
be more likely to get a response)
I can't get an image to show in a DetailsView. I am trying both an
ImageField and a template field with an image in it with databindings
to the datasource. I know the datasource works because the image
shows in the test. All I get is the RED X.

I have google searched this problem and I have seen it reported
several times but never answered. Is this a bug? Is there a
workaround?

here is my DetailsView definition......................
<aspetailsView ID="dvDetails" runat="server"
Height="50px"
Width="708px" AutoGenerateRows="False" DataSourceID="dsDetails">
<Fields>
<asp:CheckBoxField DataField="active"
HeaderText="active" SortExpression="active" />
<asp:BoundField DataField="numresumesposted"
HeaderText="numresumesposted" SortExpression="numresumesposted" />
<asp:BoundField DataField="address1"
HeaderText="address1" SortExpression="address1" />
<asp:BoundField DataField="hoursavailable"
HeaderText="hoursavailable" SortExpression="hoursavailable" />
<asp:BoundField DataField="maxhoursperweek"
HeaderText="maxhoursperweek" SortExpression="maxhoursperweek" />
<asp:BoundField DataField="resumetitle"
HeaderText="resumetitle" SortExpression="resumetitle" />
<asp:BoundField DataField="resumefilestring"
HeaderText="resumefilestring" SortExpression="resumefilestring" />
<asp:ImageField AccessibleHeaderText="Photo"
DataImageUrlField="photo">
</asp:ImageField>
<asp:TemplateField>
<ItemTemplate>
<asp:Image ID="Image1" runat="server"
Height="166px" ImageUrl='<%# Eval("photo") %>'
Width="175px" />
</ItemTemplate>
</asp:TemplateField>
</Fields>
</aspetailsView>
thanks,
Gary

If the field photo contains the binary data to make up that image, you won't
get it to work this way. Just think about it. Have you ever seen an HTML
page where the binary contents of the image are embedded into the page itself?
It's always a URL to the actual image.

So you will have to write a page (or better yet an httphandler) to stream
the binary contents from the database. And in the grid you need to supply
the image url with the url to that page/handler.

There are a number or websites that explain this in detail.

http://www.codeproject.com/aspnet/ImageBinaryStream.asp
http://www.primaryobjects.com/CMS/Article59.aspx
http://www.codeguru.com/columns/vb/article.php/c14061/

Jesse
PS: My answering this question has nothign to do with the fact that you might
have a MSDN subscription. The poeple answerign questions cannot see that
in any way. Everybody is equal (just the MVP's a little more equal than the
rest )

 

[GaryDean]

Jesse,
Thanks for the answer. I have done images this way before but the docs say
it can be done the way we were trying - thought there might be some
automatically generated streaming in the control somehow.

BTW, along with an MSDN subscription comes a "gaurantee" of a response
within either 24 or 48 hours in these newsgroups from a Microsoft support
person. I have used this for years. Look at responses to my postings and
you will see that along with community answers, I get microsoft responses to
all of my postings

 

[Jesse Houwing]

Hello GaryDean,

Jesse,
Thanks for the answer. I have done images this way before but the
docs say
it can be done the way we were trying - thought there might be some
automatically generated streaming in the control somehow.

Can you copy paste that section from the docs? I've never before seen anything
that allowed tyou to put in a bunch of data in an URL property and have it
automagically streamed as a seperate http request. I think you might have
misinterpreted it.

BTW, along with an MSDN subscription comes a "gaurantee" of a response
within either 24 or 48 hours in these newsgroups from a Microsoft
support person. I have used this for years. Look at responses to my
postings and you will see that along with community answers, I get
microsoft responses to all of my postings

There's a lot of non microsoft people here as well. But yes you are right.

Jesse

 

[GaryDean]

Jesse,
Another thought....
If what you say is true then what is the purpose of the DataImageUrlField in
the fields editor of the DetailsView? It simply points to the image
column - not a web page that streams.

 

[Jesse Houwing]

Hello GaryDean,

Jesse,
Another thought....
If what you say is true then what is the purpose of the
DataImageUrlField in
the fields editor of the DetailsView? It simply points to the image
column - not a web page that streams.

See the docs here:
http://msdn2.microsoft.com/en-us/library/system.web.ui.webcontrols.imagefield.dataimageurlfield.aspx

it is used to set up a format to use when binding to the datasource. So if
your datasource contaisn only the name of the image, or your download url
needs the name of the image as a parameter you can use this property in combination
with the dataimageurlformatstring field.

<asp:imagefield dataimageurlfield="LastName"
dataimageurlformatstring="~\Images\{0}.jpg"
alternatetext="Employee Photo"
nulldisplaytext="No image on file."
headertext="Photo"
readonly="true"/>

So it will pick the contents of the LastName column and merge that into the
dataimageurlformatstring.

The example on the page would pick all the lastnames drom the bindingsource
to build the url.

So it doesn't allow you to stream the data directly from the dataset. it
just makes it easier to setup the url to stream the actual data from. You
still need a page to fetch the data from the database or an image on disk
somewhere.

 

[Steven Cheng[MSFT]]

Thanks for Jesse's inputs,

Hi Gary,

As for the DataImageUrlField, as Jesse has said, it simply display the
value from databound field onto html page, and the value it expected is a
simple string path. e.g. "/images/logo.jpg"

And web page databinding is different from winform databinding which can
not directly bind and display binary stream data(such as image) and display
them inside a web page. If the data of your image field is of binary
stream, you may need to use another spearate httphandler to expose them and
refer the httphandler based url in your DetailsView's image column.

If the data in your image datafield does be of string path value, I think
there might exists some problem with the resolution of the image path at
either server-side or client-side. A common way to troubleshoot is as
below:

** view the page's client-side html source in brower to see whether the
output path is the expected correct path

** print out the path value which is bound in DetailsView to see whether it
is the correct one.

Anyway, if there is anything else particular in your scenario or if you
have any more specific question on this, please feel free to post here.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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