HMGET command is used to retrieve the value associated with the specified field in a hash stored at a key. In Ruby, it's commonly used when you need to fetch multiple values from a Redis hash at once, such as getting user details like name, age, and email from a user hash.
Let's assume we have a Redis hash that stores user data like following:
To get the name and email of this user using
HMGET, you would do the following:
In this example,
HMGET retrieves the values of "name" and "email" fields from the hash stored at key "user:1001".
HMGETwhen you need to retrieve multiple fields from a hash. If you only need a single field, use
HGETinstead to avoid unnecessary data transfer.
nilfor those fields. Always handle potential nils in your code.
nilvalues which can cause errors in your program where non-
nilvalues are expected.
HMGETfor single value retrieval, use
Q: What happens if the hash or field does not exist?
A: If you try to get a non-existent key/field with HMGET, it will return
Q: Can I use HMGET to fetch all fields and values from a Redis hash?
A: No, HMGET only retrieves the values of specified fields. If you want to fetch all fields and their values, use