If value exists in environment [duplicate]

This question already has an answer here:

• How to check if object (variable) is defined in R? 5 answers

Is there a way how to check if value exists in R environment and if == TRUE, assign this existing value otherwise assign something else?

In other words, I have nothing in my R right now and I created this if else statement.

test <- if_else(exists("my_value"), my_value, "my value missing, assigning this string")

Result of

 exists("my_value")

is:

exists("my_value")
[1] FALSE

But once I run whole code I get this

Error in if_else(exists("my_value"), my_value, "my value missing, assigning this string") : object 'my_value' not found