Redis HSET in Golang (Detailed Guide w/ Code Examples)

Use Case(s)

Redis' HSET command is used to set one or more field-value pairs in a hash. Common use cases include:

• Storing object-like items, where each object's properties and values are represented by the field-value pairs in the hash.
• Caching data that needs to be quickly retrieved using a key and a field name.
• Note that the hash data type in Redis doesn't support nested fields. Each value associated with a field is a string, although you can choose what to put in that string, such as plain text, a serialized object, or a binary blob.

Code Examples

Let's consider we're using the popular go-redis library.

Example 1: Set a Single Field in a Hash

package main

import (
    "context"
    "fmt"

    "github.com/redis/go-redis/v9"
)

func main() {
    client := redis.NewClient(&redis.Options{
        Addr: "localhost:6379",
    })

    err := client.HSet("user-123", "name", "John").Err()
    if err != nil {
        panic(err)
    }

    result, err := client.HGet("user-123", "name").Result()
    // You may want to handle 'redis.Nil' as well.
    if err != nil {
        panic(err)
    }

    fmt.Println("Name:", result)
}

In this example, we create a new client connection to a local Redis server. We then set the name field of the user-123 hash to John. Finally, we retrieve the name we just set and print it out.

Example 2: Set Multiple Fields in a Hash

package main

import (
    "context"
    "fmt"

    "github.com/redis/go-redis/v9"
)

func main() {
    client := redis.NewClient(&redis.Options{
        Addr: "localhost:6379",
    })

    err := client.HSet("user-123", "name", "John", "age", 20).Err()
    if err != nil {
        panic(err)
    }
}

In this example, we set multiple field-value pairs using the HSET command. Note that as of Redis version 4.0.0, the HMSET command is regarded as deprecated since it can be replaced by HSET.

Best Practices

• Always handle errors from HSET. Ignoring errors can lead to hard-to-diagnose issues.
• Reuse Redis clients as much as possible (normally by using a connection pool) rather than creating a new one for each operation. It's more efficient in terms of resources.

Common Mistakes

• A common mistake is to assume that HSET will return an error if the field already exists in the hash. HSET will simply overwrite any existing field with the new value.