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Ruby Hashes Explained
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| <<-OLIVER_QUESTION_20180530 | |
| Oliver's Question: what does "validate" mean here? | |
| self.save(validate: false) | |
| I'm trying to understand what var: means (specifically, the colon symbol) | |
| Is this specifying the name of the parameter that the value is to be matched up with? | |
| OLIVER_QUESTION_20180530 | |
| # -- LESSON: In Ruby, a hash can use Strings (eg. "almond", "twix") or symbols (eg. :almond, :peanut) as keys. -- # | |
| ## 1. Here is an example of using Strings as its keys | |
| hash_a = { "almond" => 1111, "peanut" => 2222 } | |
| hash_b = { "mango" => 1111, "pear" => 2222 } | |
| ## NOTE: hash_a's keys are "almond", "peanut". | |
| ## NOTE: hash_b's keys are "mango", "pear" | |
| ## 2. Here is an example of a hash using symbols as its keys | |
| hash_a1 = { :almond => 1111, :peanut => 2222 } | |
| hash_b2 = { :mango => 1111, :pear => 2222 } | |
| ## NOTE: hash_a's keys are "almond", "peanut". | |
| ## NOTE: hash_b's keys are "mango", "pear" | |
| ## 3. Eventually a shorthand way was created to represent hashes containing symbols | |
| hash_a1_equivalent = { almond: 1111, peanut: 2222 } # equivalent to { :almond => 1111, :peanut => 2222 } | |
| hash_b2_equivalent = { mango: 1111, pear: 2222 } # equivalent to { :mango => 1111, :pear => 2222 } | |
| ## 4. Within Rails there is a construct called a HashWithIndifferentAccess. This allows you to have a hash that can be accessed via Strings or Keys. | |
| # * NOTE: This part of the code will only work within a Rails context. | |
| hash_with_indifferent_access = HashWithIndifferentAccess.new({a: 1, b: 2, "c" => 3, :d => 4}) | |
| hash_with_indifferent_access[:a] #=> 1 | |
| hash_with_indifferent_access["a"] #=> 1 | |
| hash_with_indifferent_access[:b] #=> 2 | |
| hash_with_indifferent_access["b"] #=> 2 | |
| hash_with_indifferent_access[:c] #=> 3 | |
| hash_with_indifferent_access["c"] #=> 3 | |
| hash_with_indifferent_access[:d] #=> 4 | |
| hash_with_indifferent_access["d"] #=> 4 |
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