How to pass array elements as separate method arguments in Ruby?

Question

Scenario: A method takes arguments in this fashion

def my_method(model_name, id, attribute_1, attribute_2)
  # ...
end

All parameters are unknown, so I am fetching the model name from the object's class name, and the attributes I am fetching from that class returned as an array.

Problem: I have an array ["x", "y", "z"]. I need to take the items from each array and pass them into the method parameters after the Model as illustrated above.

Is it even possible to "drop the brackets" from an array so to speak, but keep the items and their order in tact?

Without * you could just write my_method(model_name, ary[0], ary[1], ary[2]), not much of a problem here ;-) — Stefan
– Stefan, Commented Feb 28, 2017 at 7:53

Stefan · Accepted Answer · 2017-02-28 07:47:07Z

11

yes, just use * before array:

my_method(model_name, *["x", "y", "z"])

it will result in:

my_method(model_name, "x", "y", "z")

* is a splat operator.

edited Feb 28, 2017 at 7:47

Stefan

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answered Feb 28, 2017 at 3:58

Lukasz Muzyka

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3 Comments

Alex Over a year ago

It is a very good way, I didn't know the splat operator before ;)

Drakken Saer Over a year ago

You saved me hours of frustration.

Lukasz Muzyka Over a year ago

@Alex yeah, pretty handy. I use it all the time when I deal with CSVs and have variable number of columns per row

Alex · Accepted Answer · 2017-02-28 16:49:43Z

1

The easy way is:

data = ["x", "y", "z"]
my_method(model_name, data[0], data[1], data[2])

The long way:

data = ["x", "y", "z"]
id_var = data[0]
attribute_1 = data[1]
attribute_2 = data[2]
my_method(model_name, id_var, attribute_1, attribute_2)

But the best and smartest way is the one that proposed Stefan and Lukasz Muzyka:

my_method(model_name, *["x", "y", "z"])

edited Feb 28, 2017 at 16:49

answered Feb 28, 2017 at 14:31

Alex

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2 Comments

Stefan Over a year ago

You could also use id_var, attribute_1, attribute_2 = data to assign the elements to variables.

Alex Over a year ago

you are right, but maybe this way is more readable or easy to understand

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