Existence of Key-Value Item
Understand how to verify if a key exists in a Go map using the comma ok idiom, differentiate between zero values and absent keys, and learn to delete keys safely without errors. This lesson helps you manage map key-value data accurately.
We'll cover the following...
Testing the existence of a key
We saw in the previous lesson that val1 = map1[key1] returns the value val1 associated with key1. If key1 does not exist in the map, val1 becomes the zero-value for the value’s type, but this is ambiguous. Now we can’t distinguish between this case or the case where key1 does exist and its value is the zero-value! In order to test this, we can use the following comma ok form:
val1, isPresent = map1[key1]
The variable isPresent will contain a Boolean value. If key1 exists in map1, val1 will contain the value for key1, and isPresent will be true. If ...