SilverStripe 3.1 GridField file link is re-written with HTML Entities - hyperlink

Question

I'm very new to Silverstripe (3.1). I am using it to collect applications from users. Each user uploads a file which later in the CMS somebody can download.
There is a has_one relationship for the file called 'Document.'
I want to link to that file inside a GridField. So after some searching I did the solution below - easy, and it works except for one problem.
The link does appear inside the correct column in the GridField but it has been converted through something like HTMLSpecialChars() and I can see all the HTML. For the life me I cannot figure how to stop it.
I would like to know where this conversion is taking place?
and how can I circumvent it?
$submissionGrid = new GridField('submissions', 'Submissions', $submission, $config );
$submissionGrid->addDataFields(array(
"Document" => function($row) {
$link = 'Download Document';
return $link;
},
));

Answer 1

You are pretty close.
Instead of addDataFields(), have you tried setFieldFormatting on the configuration of your gridfield?
$submissionGrid = new GridField('submissions', 'Submissions', $submission, $config );
$config = $submissionGrid->getConfig();
$config->getComponentByType('GridFieldDataColumns')->setFieldFormatting(array(
"Document" => function($value, $item) {
$link = 'Download Document';
return $link;
},
));
Depending on the fields available on the Submission Dataobject, if "Document" is something you are adding as a custom column to your gridfield, you will need to add it as well using setDisplayFields(). In this case, add this as well
$config->getComponentByType('GridFieldDataColumns')->setDisplayFields(array(
"Document" => "Link to document"
));

Answer 2

What actually worked:
I gave the right answer to jfbarrois for pointing me straight but thought I should post up the code that actually worked because it took me a while to find this answer.
It does have the inestimable advantage that it does actually work and a link is placed in a custom-formatted column in the GridField.
$config = GridFieldConfig_Base::create();
$config->getComponentByType('GridFieldDataColumns')->setDisplayFields($displayFields);
// Adding the custom named 'Download' column to the previously defined $displayFields
$config->getComponentByType('GridFieldDataColumns')->setDisplayFields(
array_merge($displayFields, array(
"Download" => "Link to document"
)
));
// Set the field formatting on the custom column inserting the real data from the 'Document' File Object
$config->getComponentByType('GridFieldDataColumns')->setFieldFormatting(array(
"Download" => function($value, $item) {
$link = 'Download Document';
return $link;
},
));
// Create the GridField
$submissionGrid = new GridField('submissions', 'Submissions', $submission, $config );