ASP.NET Core Integration

ASP.NET Core Integration

This page covers the minimal demo API bundled with the repository and a recommended dependency-injection pattern for using DeviceDetector.NET directly in application logic. For logging integration, see the dedicated Serilog.Enrichers.AspNetCore.DeviceDetector page.

Demo API — DeviceDetector.NET.Web

HomeController exposes a single GET /Home endpoint that parses the caller's User-Agent and Client Hints and returns the full result as JSON — handy as a quick manual test/demo of what the library reports for your current browser:

[HttpGet]
public object Get()
{
    DeviceDetector.SetVersionTruncation(VersionTruncation.VERSION_TRUNCATION_NONE);

    var userAgent = Request.Headers.UserAgent;
    var headers = Request.Headers.ToDictionary(a => a.Key, a => a.Value.ToArray().FirstOrDefault());
    var clientHints = ClientHints.Factory(headers);

    var result = DeviceDetector.GetInfoFromUserAgent(userAgent, clientHints);
    return result;
}

Run it locally to see the shape of ParseResult<DeviceDetectorResult> returned by GetInfoFromUserAgent for any real request hitting your dev machine.

Dependency injection pattern

Issue #83 raised a fair complaint: there's no built-in IServiceCollection extension, and the library isn't itself injectable — DeviceDetector is a per-parse object you construct with a User-Agent, not a long-lived service. If what you want is @inject a service and call IsMobile(Request) from a Razor page or controller with no further ceremony, wrap it yourself with a small service like this:

public interface IDeviceDetectionService
{
    bool IsMobile(HttpRequest request);
    DeviceDetector Detect(HttpRequest request);
}

public class DeviceDetectionService : IDeviceDetectionService
{
    public DeviceDetector Detect(HttpRequest request)
    {
        var headers = request.Headers.ToDictionary(a => a.Key, a => a.Value.ToArray().FirstOrDefault());
        var clientHints = ClientHints.Factory(headers);

        var dd = new DeviceDetector(request.Headers.UserAgent, clientHints);
        dd.Parse();
        return dd;
    }

    public bool IsMobile(HttpRequest request) => Detect(request).IsMobile();
}

Register it once, as a singleton — the service itself holds no per-request state, so one instance can safely serve every request:

builder.Services.AddSingleton<IDeviceDetectionService, DeviceDetectionService>();

Then, in a Razor page or controller:

@inject IDeviceDetectionService DeviceDetection

@if (DeviceDetection.IsMobile(Context.Request))
{
    <p>Mobile layout</p>
}

Do I need to worry about caching here?

Not by default. new DeviceDetector(...) followed by Parse() already benefits from the process-wide fragment cache described in Caching with zero extra setup — SetCache(new DictionaryCache()) is what DeviceDetector uses internally already; calling it explicitly only matters if you want to swap in a different ICache implementation. Creating a fresh DeviceDetector instance per request is intentional and cheap: instances are lightweight, and the data they end up reusing (regex fragment results) already lives in a shared static cache, not in the instance itself.

If profiling shows parsing itself (not instance allocation) is a bottleneck under load, and you don't need Client Hints for the check in question, swap Detect's body for LRUCachedDeviceDetector.GetDeviceDetector(userAgent) instead of constructing a new instance — see the Caching page for why that trade-off (no Client Hints support) exists and when it's worth it.

Choosing where to detect

• Use the Serilog enricher for anything you want automatically attached to all logs for a request (errors, warnings, audit trails).
• Use DeviceDetector.GetInfoFromUserAgent directly, or the DI wrapper above, when you need the parsed result in application logic, not just in logs (e.g. serving a different response for mobile vs. desktop).