HEXISTS command in Redis is used to determine if a specific field is an existing key in a hash. Common use cases are for checking the existence of data before performing operations such as updates or deletes, and for conditional logic in scripts or applications.
Let's assume we have Redis running in localhost and a hash named "user:1000" containing fields like "name", "email".
Here's how you can use the HEXISTS function with python and redis-py:
In this example,
r.hexists("user:1000", "email") checks if the field
user:1000. It returns True if it exists, False otherwise.
HEXISTSbefore trying to access it. Proper handling of non-existing keys will prevent unexpected results.
HEXISTSreturns 1 (True in Python) if the field exists in the hash, and 0 (False in Python) if the field does not exist or hash does not exist.
1. What does
HEXISTS return if the specified hash doesn't exist?
It returns 0 (False in Python). It means either the hash or the field does not exist.
2. Is it necessary to use
HEXISTS before using
No, it's not necessary but it is a good practice to check whether a field exists before trying to access or modify it.