check for empty? in the view

rubyonrails-talk
#1

I nned to get an associsted name from one table dependent on the related
id value in another table when rendering the view but cant figure out
the syntax to handle pontential empty values:-

i.e. docv.policy_id OR docv.standard_id will exist and therefore link
back to the policies OR the standards table respectively but ONLY ONE
will exist.

Therefore I need to check the existance of each field before attempting
to get the PolicyName OR StandrdsName from the related table otherwise
the empty item gives me a '.nil value' error.

<% @docversions.each do |docv| %>
<tr>
<td><% docv.modifier %></td>
<td><%= docv.comment %></td>
<td><%= docv.policy.PolicyName if docv.policy_id %></td>
<td><%= docv.standard.StandardsName if docv.standard_id %></td>

Can someone advise the syntax to use in the view to achieve this. I have
also tried ....."if !docv.standard_id.empty?".

Thanks

#2

<% @docversions.each do |docv| %>
<tr>
<td><% docv.modifier %></td>
<td><%= docv.comment %></td>
<td><%= docv.policy.PolicyName if docv.policy_id %></td>
<td><%= docv.standard.StandardsName if docv.standard_id %></td>

Can someone advise the syntax to use in the view to achieve this. I have
also tried ....."if !docv.standard_id.empty?".

don't think you need anything more than if docv.policy

Fred

#3

Frederick Cheung wrote:

don't think you need anything more than if docv.policy

Fred

Thanks Fred but I still get an error:-

I gave a vey simple example and it may be fairer to give a slightly
different example that I am working on where the potential nil value is
the default selected value of a drop-down list:-

<tr>
<td><select name="risk[LastReviewed(1i)]">
<option value="<%= @risks.LastReviewed.year if @risks.LastReviewed.year
%>" selected="selected"><%= @risks.LastReviewed.year %></option>
<option value="2008">2008</option>
.......etc

and the error I get is:-

You have a nil object when you didn't expect it!
The error occured while evaluating nil.year

#4

Frederick Cheung wrote:

don’t think you need anything more than if docv.policy

Fred

Thanks Fred but I still get an error:-

I gave a vey simple example and it may be fairer to give a slightly

different example that I am working on where the potential nil value is

the default selected value of a drop-down list:-

@risks.LastReviewed.year %> 2008

…etc

and the error I get is:-

You have a nil object when you didn’t expect it!

The error occured while evaluating nil.year

–

That’s because @risks.LastReviewed is the one that is nil
use

#5

mahmoud said wrote:

Thanks Fred but I still get an error:-
.......etc

and the error I get is:-

You have a nil object when you didn't expect it!
The error occured while evaluating nil.year
--

That's because @risks.LastReviewed is the one that is nil
use
<option value="<%= @risks.LastReviewed.year if @risks.LastReviewed%>"
selected="selected">

--
Mahmoud Said
Software Developer
blog.modsaid.com
www.eSpace.com.eg
+20-16-1223857

Mahmoud,

Still not quite seeing why @risks.LastReviewed can be checked for
existance but @risks.LastReviewed.year cant be. I would have thought an
element of the date would be able to be checked in the same way as the
whole date.

Anyhow...you help was great and has allowed me to sort the problem so
thanks very much indeed.

Just for anyone else....I also needed to put the existance check in the
displayed element of the drop-down selection thus:-

<option value="<%= @risks.LastReviewed.year if @risks.LastReviewed%>"
selected="selected"><%= @risks.LastReviewed.year if
@risks.LastReviewed%></option>

Martyn

#6

mahmoud said wrote:

Thanks Fred but I still get an error:-

…etc

and the error I get is:-

You have a nil object when you didn’t expect it!

The error occured while evaluating nil.year

–

That’s because @risks.LastReviewed is the one that is nil

use

<option value="<%= @risks.LastReviewed.year if @risks.LastReviewed%>"

selected=“selected”>

–
Mahmoud Said

Software Developer

blog.modsaid.com

www.eSpace.com.eg

+20-16-1223857

Mahmoud,

Still not quite seeing why @risks.LastReviewed can be checked for

existance but @risks.LastReviewed.year cant be. I would have thought an

element of the date would be able to be checked in the same way as the

whole date.

In @risks.LastReviewed.year you are calling the year method of the @risks.LastReviewed object which, I assume, is of class Time . if that object is nil then it is no longer a Time object… it is a nil object of type NilClass … and you can only call NilClass methods for it.