Set a default value to a "text/blob" field at creation?

Rails
1

Is it possible somehow to incorporate “this is a text” into a
“blob/text”-value in the database when the row is created?
It’s not possible to do with a default value hence it’s a
“blob/text”-value.

At the moment I create the row for a user with:

@presentation = current_user.presentation
@presentation = current_user.create_presentation unless @presentation

2

I tried to create this in my lib file string.rb to show something else
if the value was nil…(and required the ‘string.rb’ in my application
helper)

def or_empty(alternate)
(self.nil? or self == “”) ? alternate : self
end

but that didn’t work either.

3

Julian L. wrote:

You’d need to open the class up to do this.

class String
def or_empty(alternate = ‘default’)
self.blank? ? alternate : self
end

That would work.

Julian.

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OUT APRIL 6
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Nope, that doesn’t do it,

I still get an error
“The error occurred while evaluating nil.or_empty”

in this line of my show-view:
<%= h @presentation.pres.or_empty(“No presentation has been entered”)%>

because the there exists nothing in the pres-field. This is what I’m
trying to fix.

what do you mean with:

You’d need to open the class up to do this.

4

You’d need to open the class up to do this.

class String
def or_empty(alternate = ‘default’)
self.blank? ? alternate : self
end

That would work.

Julian.

Learn Ruby on Rails! CHECK OUT THE FREE VIDS (LIMITED TIME) VIDEO #3
OUT APRIL 6
http://sensei.zenunit.com/

5

Frederick C. wrote:

On 4 Apr 2008, at 10:08, Dag S. wrote:

because the there exists nothing in the pres-field. This is what I’m
trying to fix.

How about you do this in your model

def pres
value_in_database = self[:pres]
#do something with value_in_database
end

Fred

I’m not quite sure I completely understand… =/

6

On 4 Apr 2008, at 10:47, Dag S. wrote:

#do something with value_in_database
end

Fred

I’m not quite sure I completely understand… =/

Overwrite the accessor that rails provides, using self[:pres] to get
at the original value.

Fred

7

On 4 Apr 2008, at 10:08, Dag S. wrote:

because the there exists nothing in the pres-field. This is what I’m
trying to fix.

How about you do this in your model

def pres
value_in_database = self[:pres]
#do something with value_in_database
end

Fred

8

Frederick C. wrote:

On 4 Apr 2008, at 10:47, Dag S. wrote:

#do something with value_in_database
end

Fred

I’m not quite sure I completely understand… =/

Overwrite the accessor that rails provides, using self[:pres] to get
at the original value.

Fred

Alright, thanx a lot, solved the problem!