Every application needs to store data and almost every app developer running on the same problem which is you have some data that you pulled from the internet or the user entered it to the application, you need to save that data.

If you are looking to accomplish to make a web request, save the result locally, and have it expire after a given amount of time, that is basically what we called caching.

There are a lot of great solutions out there to cache data, but if you are looking for a minimal amount of dependencies, you're on the right page, mate!

In this article, I’m going to show you how to do data caching by using the Monkey Cache library by James Montemagno.

What is Monkey Cache?

Monkey Cache enables you to easily store any type of data or just a simple string that you can easily serialize and deserialize back and forth. The key here is that you can set an expiration data associated with that data. So you can say this data should be used for the next few days.

Installing Monkey Cache

Monkey Cache consists of one core NuGet package (MonkeyCache) with three backing store providers. You can choose the backend that best fits your needs.

If you are already using one of these databases depending in your application, you may already have SQLite or LiteDB installed so these would be your natural choice.

Setup

Once Monkey Cache is installed in your project, it is time to start storing objects.

Before calling any method, it is required that you set an ApplicationId for your application so a folder is created specifically for your app on disk. This can be done with a static string:

Barrel.ApplicationId = "your_unique_name_here";

Caching a Web Request

Let's have a web request and we get some json response from the server. What we want is the ability to cache this data incase the app goes offline, but also we need it to expire after 24 hours.

static readonly HttpClient httpClient = new HttpClient();

public async Task> GetRandomJokesAsync()
{
    var endpoint = string.Format("https://official-joke-api.appspot.com/jokes/programming/ten");

    if(Connectivity.NetworkAccess == NetworkAccess.Internet) 
    {
        HttpResponseMessage httpResponse = await httpClient.GetAsync(endpoint);
        string httpResult = httpResponse.Content.ReadAsStringAsync().Result;
        var httpData = JsonConvert.DeserializeObject>(httpResult);
        Barrel.Current.Empty(endpoint);
        Barrel.Current.Add(key: endpoint, data: httpData, TimeSpan.FromDays(1));
        return httpData;
    }

    else 
    {
        return Barrel.Current.Get>(endpoint);
    }
}

The Add method (which also updates the item) takes in a unique key, some data, and a time span

Demo

WITHOUT Monkey Cache - as you can see right here, the app is prone to crashing and seems like an empty screen except a message "Network error. Please check your connection".

WITH Monkey Cache - Won’t it be a better user experience if you could see the latest data cached?

There you have it! No need to re-structure your entire app! Now all of your web requests will be cached for any amount of time and you can integrate Monkey Cache into your existing source code without any modifications to your network code.

Try it in your own, you can find all of the code of our demo app in this GitHub repo here .

Until next time! Happy Xamarin coding!