LinkBuilding 0.1.68

Link Building

Strongly typed, cached URL building for ASP.NET Core using lambda expressions:

_linkBuilder.BuildUriFromExpression<InvoicesController>(
    httpContext,
    c => c.GetInvoice(2));

_linkBuilder.BuildUriFromExpression(
    httpContext,
    (InvoicesController c) => c.GetInvoice(2));

Features:

• Extracts action name, controller name, and route values from expression
• Delegates URL generation to LinkGenerator
• Supports ActionName, Area, NonAction and NonController attributes
• Supports Controller and Async suffixes
• Supports all cases documented in LinkBuilding.Tests
• Supports LinkOptions
• Supports bypassable caching

Attribute routing:

If multiple URL paths match an action in your controller:

[HttpGet("api/invoices/{invoiceId}", Name = "ApiGetInvoice")]
[HttpGet("invoices/{invoiceId}", Name = "GetInvoice")]
public InvoiceResource GetInvoice(int invoiceId)

you can specify an endpoint name to build an endpoint specific URL:

_linkBuilder.BuildUriFromExpression<InvoicesController>(
    httpContext,
    c => c.GetInvoice(2),
    "ApiGetInvoice");

_linkBuilder.BuildUriFromExpression<InvoicesController>(
    httpContext,
    c => c.GetInvoice(2),
    "GetInvoice");

LinkBuilder will validate whether such endpoint name is defined in action's HttpMethod, AcceptVerbs, or Route attribute and build URL based on it and expression's route values.

To further improve on this, you can use classes such as Microsoft.Azure.Management.ResourceManager.Fluent.Core.ExpandableStringEnum instead of strings to define your endpoint names. That would require you to write a simple adapter class that takes a string from your class and passes it to LinkBuilder.

Performance:

Extracting values from expression trees does introduce some overhead. To work around this problem, LinkBuilding uses AspNetWebStack's CachedExpressionCompiler, so that equivalent route values' values' expression trees only have to be compiled once.

Additionally, it uses its internal Microsoft.Extensions.Caching.Memory.MemoryCache instance to cache extracted controller names, action names, and route values' keys within the scope of the application lifetime.

This means that, for example, on 2017 Surface Book 2 you are able to build 100000 URLs in a second using a template like this: https://localhost:44339/api/invoices/{id}.

Setup:

• Install LinkBuilding via NuGet Package Manager, Package Manager Console or dotnet CLI:

Install-Package LinkBuilding

dotnet add package LinkBuilding

• Register LinkBuilding in a service container (each CacheEntry will have a size of 1):

builder.Services.AddLinkBuilding();

builder.Services.AddLinkBuilding(o =>
{
    o.SizeLimit = 100;
    o.CompactionPercentage = 0.75;
});

• Request an instance of ILinkBuilder singleton from any constructor in your app:

public class InvoicesController
{
    private readonly ILinkBuilder _linkBuilder;

    public InvoicesController(ILinkBuilder linkBuilder)
    {
        _linkBuilder = linkBuilder;
    }
}

Examples:

Check out LinkBuilding.Examples for working examples.

Credits:

• LinkBuilder and CachedExpressionCompiler by https://github.com/aspnet/AspNetWebStack (Apache-2.0 license)