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Using Redis

Redis (vapor/redis) is a pure-Swift, event-driven, non-blocking Redis client built on top of SwiftNIO.

You can use this package to interact send Redis commands to your server directly, or as a cache through Vapor's KeyedCache interface.

Redis Commands

Let's take a look at how to send and recieve data using Redis commands.

Connection

The first thing you will need to send a Redis command is a connection. This package is built on top of DatabaseKit, so you can use any of its convenience methods for creating a new connection.

For this example, we will use the withNewConnection(to:) method to create a new connection to Redis.

router.get("redis") { req -> Future<String> in
    return req.withNewConnection(to: .redis) { redis in
        // use redis connection
    }
}

See DatabaseKit → Overview for more information.

Available Commands

See RedisClient for a list of all available commands. Here we'll take a look at some common commands.

Get / Set

Redis's GET and SET commands allow you to store and later retrieve data from the server. You can pass any Codable type as the value to this command.

router.get("set") { req -> Future<HTTPStatus> in
    // create a new redis connection
    return req.withNewConnection(to: .redis) { redis in
        // save a new key/value pair to the cache
        return redis.set("hello", to: "world")
            // convert void future to HTTPStatus.ok
            .transform(to: .ok)
    }
}

router.get("get") { req -> Future<String> in
    // create a new redis connection
    return req.withNewConnection(to: .redis) { redis in
        // fetch the key/value pair from the cache, decoding a String
        return redis.get("hello", as: String.self)
            // handle nil case
            .map { $0 ?? "" }
    }
}

Delete

Redis's DELETE command allows you to clear a previously stored key/value pair.

router.get("del") { req -> Future<HTTPStatus> in
    // create a new redis connection
    return req.withNewConnection(to: .redis) { redis in
        // fetch the key/value pair from the cache, decoding a String
        return redis.delete("hello")
            // convert void future to HTTPStatus.ok
            .transform(to: .ok)
    }
}

See RedisClient for a list of all available commands.

Keyed Cache

You can also use Redis as the backend to Vapor's KeyedCache protocol.

router.get("set") { req -> Future<HTTPStatus> in
    let string = try req.query.get(String.self, at: "string")
    return try req.keyedCache(for: .redis).set("string", to: string)
        .transform(to: .ok)
}

router.get("get") { req -> Future<String> in
    return try req.keyedCache(for: .redis).get("string", as: String.self)
        .unwrap(or: Abort(.badRequest, reason: "No string set yet."))
}

See DatabaseKit → Overview for more information.

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