如何将Hash与Rails控制器的参数合并？

Question

Given a Hash with symbol keys, eg: { name: 'Jeff' } , what would be the easiest method to merge it with controller's params ?

Using the straightforward merge produces the wrong result:

> {a: 1}.merge(HashWithIndifferentAccess.new(a: 2, b: 3))
  => {:a=>1, "a"=>2, "b"=>3}

The desired result is {:a=>2, :b=>3} .

Answer 1

There are 2 possible ways to merge a Hash with the params of rails:

1. Use HashWithIndifferentAccess.new(YOUR_HASH).merge(params) or vice versa
2. Use YOUR_HASH.with_indifferent_access.merge(params) or vice versa

The order matters in both variants. The parameter of merge(XXX) overrides the settings of your Hash which called the merge method. If you want it vice versa, simply swap them.

FYI: Rails adds a new method to the Hash class: with_indifferent_access -> Rails Doc