Dig method for nested access in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the dig method do in Ruby?

The dig method safely accesses nested elements inside hashes or arrays without raising errors if a key or index is missing. It returns nil instead.

beginner

How do you use dig to get a value from a nested hash?

You call dig on the hash and pass the keys in order. For example, hash.dig(:key1, :key2) returns the value inside :key2 nested in :key1.

beginner

What happens if a key or index does not exist when using dig?

Instead of raising an error, dig returns nil. This helps avoid crashes when accessing deep nested data.

intermediate

Can dig be used with arrays as well as hashes?

Yes! You can use dig to access nested arrays by passing indexes along with hash keys. For example, array.dig(0, :key) works if the first element is a hash.

intermediate

Why is dig better than chaining multiple [] calls?

Because chaining [] calls can raise errors if any key or index is missing. dig safely returns nil without crashing, making code cleaner and safer.

What does hash.dig(:a, :b) return if :a exists but :b does not?

A Raises an error

B nil

C Returns the whole hash

D Returns false

dig returns nil if any key in the chain is missing.

Which of these is a correct use of dig to access nested data?

A hash.dig(:key1, :key2)

B hash[:key1][:key2]

C hash.get(:key1, :key2)

D hash.fetch(:key1).fetch(:key2)

dig takes multiple keys and safely returns nested values.

Can dig be used to access elements inside arrays?

A Only if arrays are converted to hashes

B No, only hashes

C Only with strings

D Yes, by passing indexes as arguments

dig works with arrays by passing numeric indexes.

What is the main advantage of using dig over chaining [] calls?

A It prints the nested value

B It runs faster

C It avoids errors if keys or indexes are missing

D It modifies the original data

dig safely returns nil instead of raising errors.

What will [{a: 1}].dig(0, :a) return?

A 1

B nil

C Raises an error

D An array

The first element is a hash with key :a, so dig returns 1.

Explain how the dig method helps when accessing nested hashes or arrays.

Think about what happens if a key or index is missing.

Describe a situation where using dig is better than chaining multiple [] calls.

Consider what happens if one part of the chain is missing.