In Redis, checking if a key exists is quite commonly done while retrieving values from Redis cache. If your application is written in PHP, you might need to check whether a key exists before trying to retrieve its value to avoid possible errors or exceptions.
Let's assume you're already connected to your Redis instance. Here's an example demonstrating how to check if a key exists.
In this code, we're first creating a new instance of the Redis class and connecting to the local Redis server. We then use the
exists method to check if the key
'testKey' exists. If it does, we print 'Key exists', else we print 'Key does not exist'.
exists. Instead consider using Redis transactions (MULTI/EXEC commands) or Lua scripting for complex atomic operations.
existsfunction returns the number of keys existing among those specified as arguments. So always checking it in boolean context might not give the expected results if you are checking multiple keys at once.
null. Therefore, always check if a key exists before trying to get its value.
Q: Can I use wildcards with the
A: No, the
exists function doesn't support patterns or wildcards. If you need to check for keys following a certain pattern, consider using the
keys command first, and then check for existence for each key.