How to set a dynamic attribute

Question

Is there a way to set col as dynamic or convert it in some way to a valid attribute? It is currently throwing the error: undefined method `col=' for #...

def copy_stock_data_from_sandbox(cntrlr)
  source_table = cntrlr.singularize.classify.constantize
  dest_table = source_table.new
  source_table.column_names.each do |col|
    dest_table.col = xyz    # <------ This is the line in question
  end
  dest_table.save
end

Also, not sure if the title is accurate, please suggest if 'dynamic attribute' is the wrong term for this situation. Thanks

score 16 · Accepted Answer · answered Mar 30 '12 at 00:34

16

I believe that you're looking for the following:

dest_table.send(:"#{col}=", xyz)

answered Mar 30 '12 at 00:34

Robin

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score 13 · Answer 2 · edited Apr 01 '14 at 03:34

13

You can try

dest_table.write_attribute(col, xyz)

OR

dest_table[col] = xyz

OR

dest_table.send("#{col}=", xyz)

edited Apr 01 '14 at 03:34

lulalala

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answered Mar 30 '12 at 00:39

Harish Shetty

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1

`write_attribute` is a private method – Artur INTECH Aug 08 '17 at 11:25

score 0 · Answer 3 · answered May 05 '22 at 16:25

Perhaps a more idiomatic Rails solution would be to use

assign_attributes or attributes=(which is an alias of assign_attributes).

attrs = User.column_names.each_with_object({}) do |col, hash|
  hash[col] = xyz
end

dest_table.assign_attributes attrs

Also, related question:

Rails update_attributes without save?

How to set a dynamic attribute

3 Answers3