How to Dynamically name a Hash key in Ruby

Question

I'm trying to make a 'render' call in an erb file where the key of the hash is dynamically named. For example...

<% object_type_abbr = ["pos", "job_description", "policy", "procedure", "step", "task", "product"] %>

<%= render path.to_s, 
        model_id: @model.id,
        object_type_abbr[i]: orphan,
        row_no: row_no,  
        is_orphan: true 
%>

The problem is this syntax is not recognized. I have tried using the #{ruby var name} syntax (suggested here), but of course this doesn't work in HTML.

I've also tried object_type_abbr[i].to_sym, which makes no difference.

I know this has to exist, but can't find it.

Answer 1

One solution is to use the => notation for that entry in the hash e.g.

model_id: @model.id
object_type_abbr[i].to_sym => orphan,
....

The standard way to map keys to values in a hash is using the key => value (rocket) notation.

When you write model_id: @model.id this is shorthand for :model_id => @model.id - Ruby provides this shorthand because creating hashes where the keys are symbols is such a common use case. But it isn't valid to use this style of syntax for something like object_type_abbr[i]: where the thing of the left of the colon isn't the name for a symbol.

When you use the => notation the key can be any expression, including one that evaluates to a symbol.