Fetching all keys and values from a hash at once in Ruby

Question

In **Ruby, I want to fetch all keys and values at once without needing to iterate through the hash.

The keys are variables and the values of data type boolean.

In the new Example, the only parameters, which are exchangeable, are var1 => true and var2 => true. So, I want that the hash keys are treated as keywords.

New Example:

var1 = "Attr1"
var2 = "Attr2"
var3 = "Attr2"

hash = {var1 => true, var2 => true}

def method(h = {})

    puts("Works")

end


method(hash, var3 => true) #Error

Old Example:

hash = {var1 => true, var2 => false}
self.some_method_i_cant_change_1(var1 => true, var2 => false, var3 => true)
self.some_method_i_cant_change_2(var1 => true, var2 => false, var3 => true)
... n methods
self.some_method_i_cant_change_n(var1 => true, var2 => false, var3 => true)

It's not possible to pass the hash to that method directly.

So, self.some_method_i_cant_change(hash, var3 => true) isn't allowed

there is a double splat, so hash keys are treated as keywords: `self.some_method_i_cant_change(**hash)` — Alex, Aug 03 '23 at 16:21
`foo(var1 => true, var2 => false)` is equivalent to `foo({var1 => true, var2 => false})` or `foo(hash)` with `hash = {var1 => true, var2 => false}`. Can you double check how the method is called? — Stefan, Aug 03 '23 at 18:41
@Stefan If there are predefined values, it doesn't work. I will edit my post to make it more clear. Example: `a={"h" =>1, "b" => 2}` `def method(option={})` `method("z"=>1,a)` results in an error. And `method("z"=>1,**a)` does work — cd4user, Aug 03 '23 at 19:47
Maybe I'm being dense, but I don't understand your question and could really use a minimal reproducible example. I don't understand how the `some_method_i_cant_change_*` methods are intended to use their arguments. — pjs, Aug 03 '23 at 22:21
Can you show the method signatures? How are they defined and what arguments do they take? — Stefan, Aug 04 '23 at 06:40

Ben Trewern · Answer 1 · 2023-08-03T16:18:05.547

0

Can you do something like this:

hash = {var1 => true, var2 => false}
self.some_method_i_cant_change(*(hash.map { |k, v| {k =>  v} }))

edited Aug 03 '23 at 16:18

answered Aug 03 '23 at 16:09

Ben Trewern

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Thank you for answering my question. Unfortunately, i need to handle several methods, so I guess it's a good solution for one method but not for several methods. I will edit my post to be more clear, thank you – cd4user Aug 03 '23 at 16:21

score 0 · Accepted Answer · answered Aug 04 '23 at 16:47

It is hard to understand the issue, but as I understand you need to call some method and pass single argument as hash using few existing hashes

var1 = "Attr1"
var2 = "Attr2"
var3 = "Attr3"

hsh = { var1 => true, var2 => true }

def some_method(hsh = {})
  p hsh
end

# With hashes merge
some_method(hsh.merge(var3 => true))

# Using double splat
some_method(var3 => true, **hsh)

# With mutation of original hash
hsh[var3] = true
some_method(hsh)

Fetching all keys and values from a hash at once in Ruby

2 Answers2