How to check value null in ruby on rails 3?

Question

I have create new array jobs and j.id is start from 423 and loop creates array index from 0 to total job ids with null value from 0 to 422 id. So my question is how to set condition to check the null value of j.name?

@jobs = []
demo.demojobs.each do | j |
    if j.name != null #condition 
        @jobs[j.id] = j.name
    end
end

I am working on rails version 3.2.11

Output:

pipe
0: null
1: null
.
.
.
.
423:    "jobname"
424:    "jobname"
425:    "jobname"
426:    "jobname"
427:    "jobname"

Can you please format your array as 423 "jobname" is weird array it can be ['423 jobname', 424 jobname] — Tanay Sharma
– Tanay Sharma, Commented Jan 23, 2019 at 13:01
If your output array is like ['423 jobname', '424 jobname'] check my updated answer hope it helps — Tanay Sharma
– Tanay Sharma, Commented Jan 23, 2019 at 13:06
What is the actual input here? Is this data that you are fetching from a database query? — max
– max, Commented Jan 23, 2019 at 15:32

mrzasa · Accepted Answer · 2019-01-23 12:11:21Z

2

nil value is interpreted as false in conditions, so you can write:

@jobs = []
demo.demojobs.each do | j |
    if j.name 
        @jobs[j.id] = j.name
    end
end

or in a more concise manner:

@jobs = []
demo.demojobs.each do | j |         
  @jobs[j.id] = j.name if j.name
end

You can also use #nil? method if you want to check explicitly:

@jobs = []
demo.demojobs.each do | j |
    if !j.nil? 
        @jobs[j.id] = j.name
    end
end

There is a nice blogpost explaining various options: https://blog.arkency.com/2017/07/nil-empty-blank-ruby-rails-difference/

edited Jan 23, 2019 at 12:11

answered Jan 23, 2019 at 12:09

mrzasa

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4 Comments

Varinder Sohal Over a year ago

I have try all conditions but still same issue array start from 0 index.

mrzasa Over a year ago

I'm not sure if I understand that problem with 0 index, could you tell more about it?

Varinder Sohal Over a year ago

I have j.id which is start from 423 so i want array create from 423 index not from 0 index.

Tanay Sharma Over a year ago

What is your output now with answers you have tried ?

mrzasa · Accepted Answer · 2019-01-23 12:10:37Z

1

it's nil in Ruby, not null You can check if an object is nil by calling present? or blank?.

j.name.present?

this will return false if the name is an empty string or nil .

or you can use

j.name.blank?

edited Jan 23, 2019 at 12:10

mrzasa

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answered Jan 23, 2019 at 12:07

Umar Khan

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Comments

Tanay Sharma · Accepted Answer · 2019-01-23 13:20:51Z

1

how to set condition to check the null value of j.name?

There are many ways to check for null/nil or an empty string in ruby

present? This will return true or false
```
j.name.present?
```
blank? This is opposite of present?
```
j.name.blank?
```
j.name == nil
empty? can be used on strings, arrays and hashes.

Edit:

@jobs = {}
#in your loop
@jobs[j.id] = j.name if j.name #you can use any condition here to check nil

edited Jan 23, 2019 at 13:20

answered Jan 23, 2019 at 12:11

Tanay Sharma

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2 Comments

Varinder Sohal Over a year ago

423, 424 are index of array not a value with jobname i need output like 423: jobname.

Tanay Sharma Over a year ago

array index can not be start from 423 if you want like this you can use hash instead of array @jobs = {423: 'jobname', 424: 'jobname'} like this

mrzasa · Accepted Answer · 2019-01-23 12:10:04Z

0

You can use present? or blank? in condition. Your code should be

if j.name.present? #condition 
   @jobs[j.id] = j.name
end

edited Jan 23, 2019 at 12:10

mrzasa

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answered Jan 23, 2019 at 12:05

Milind Patel

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