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ViewsHow can I replace null value with n/a in ruby on rails?
I am working on dynamic chart created through chartkick and chart.js in rails.
.
The data got null is not the problem. The problem is that I want to display null/empty to n/a.
My chart looks like:
To solve this, I first update the database through the code mention below:
Roster.where(caste_group: "").update_all(caste_group:"n/a")
But this is exactly not what I wanted. Everytime updating the database is not efficient. Then I used transform key helper. The code goes as
caste_group = Roster.group(:caste_group).count
@caste_group = caste_group.transform_keys{ |key| key==""?
"n/a":key }
Here Roster is the model which consist of following attribute caste_group as string and user select caste_group as dropdown.
Using this transform key helper I got the result which doesn't display null value. null/empty value isn't rename to n/a.
And my code in a view goes as
= line_chart @event_chart,discrete:true, legend: "bottom",curve: false,
colors: ["#67b55e","#d43766","#729be0"]
3 answers
Answer question0
I think you can do this at many levels, so depends on what you need. One way to solve this would be to set a default value in the database. So every time your model is saved with null it will actually be saved as "n\a".
You can run a migration like so:
change_column_default :rosters, :caste_group, "n\a"
But maybe you don't want to edit all the data in the DB. In that case, you can do it at the model or presenter level. I think the code you posted from the helper is all right. Are you not satisfied with it?
0
If your query can return null, and "", e.g
Roster.group(:caste_group).count
{
nil=>12,
''=>123,
'name_first'=>2
}
This can help
sql = <<-SQL
SELECT
CASE
WHEN caste_group IS NULL
THEN 'n/a'
WHEN caste_group=''
THEN 'n/a'
ELSE caste_group
END AS caste_group,
count(*)
FROM rosters
GROUP BY 1
SQL
result = ActiveRecord::Base.connection.execute(sql).to_a
This will compile NULL or '' to 'n/a'.
example result:
[
{"caste_group"=>"n/a", "count"=>"1"},
{"caste_group"=>"name_first", "count"=>"2"}
]
Next you can transform this in needed hash.
result.each_with_object({}) { |caste_group, res| res[caste_group['caste_group']] = caste_group['count'] }
e.g
{"n/a"=>"1", "name_first"=>"2"}
0
I thankfully solves this. The problem with mine is that I have already updated the database to "n/a". So, when I change the key through transform_keys I am facing the problem. After that I rename n/a to "N/A" and solves for me.
caste_group = Roster.group(:caste_group).count
@caste_group = caste_group.transform_keys{ |key| key==""? "N/A":key }
I am posting the answer because it might be helpful for others in future.