How to iterate if object can be string or array

Question

I have an object in a rails model that can either be a string or an array. In my view I have the following:

<% current_user.transaction[:account_name].each do |name| %>

If the object account_name is a string, then it throws an error.

I want to run something like this:

<% current_user.transaction[:account_name].each, if sting? each_line do |name| %>

using each_line if the object is a string, but using each if it is an array. I am not sure if this is the best solution. Any ways to make this work regardless of whether the object is an array or string?

"I have an object [...] that can either be a string or an array" – that is the problem you should fix. — Stefan
– Stefan, Commented Jun 3, 2016 at 6:22

Santhosh · Accepted Answer · 2016-06-03 06:27:18Z

6

You can use the splat operator. eg:

str = "hello"
arr = ["hi"]

[*str]
# => ["hello"] 
[*arr]
# => ["hi"]

So your code becomes

[*current_user.transaction[:account_name]].each do |name|

answered Jun 3, 2016 at 6:27

Santhosh

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2 Comments

songyy Over a year ago

Cool I didn't know this syntax before

Stefan Over a year ago

Note that * calls to_a under the hood which can have undesired results if your objects implement a custom to_a, e.g. [*Time.now]

songyy · Accepted Answer · 2016-06-03 06:04:46Z

3

<% Array(current_user.transaction[:account_name]).each do |name| %>
   balaballa
<% end %>

Note that Array(element) would do nothing if you pass in an array, and try to convert the element with array if it is not an array.

If element is nil, then it would simply return you [], and nothing would be looped.

answered Jun 3, 2016 at 6:04

songyy

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5 Comments

Dinesh Saini Over a year ago

What if array is null?

songyy Over a year ago

@DineshSaini: Array(nil) = []

songyy Over a year ago

@DineshSaini: since Array(nil) give u empty array, it would be [].each

Dinesh Saini Over a year ago

Correct we have to handle for nil in the loop, right? (+1 for you)

songyy Over a year ago

@DineshSaini: nope. if current_user.transaction[:account_name] is nil, then an empty array would be returned. (instead of [nil]). Meaning, [].each would never execute.

jack-nie · Accepted Answer · 2016-06-03 06:02:23Z

0

<% if current_user.transaction[:account_name].is_a?(String) %>
  <% current_user.transaction[:account_name].each_line do |name| %>
      balaballa
  <% end %>
<% elsif current_user.transaction[:account_name].is_a?(Array)%>
  <% current_user.transaction[:account_name].each do |name| %>
      balaballa
  <% end %>
<% end %>

answered Jun 3, 2016 at 6:02

jack-nie

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1 Comment

Dinesh Saini Over a year ago

You have missed the case if array is null and loop is calle

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