覆盖Webapi OData链接的主机 [英] Override host of webapi odata links

问题描述

我正在使用WebAPI 2.2和Microsoft.AspNet.OData 5.7.0创建支持分页的OData服务.

I'm using WebAPI 2.2 and Microsoft.AspNet.OData 5.7.0 to create an OData service that supports paging.

当托管在生产环境中时，WebAPI驻留在不对外公开的服务器上，因此OData响应中返回的各种链接(例如@odata.context和@odata.nextLink)指向内部IP地址，例如. http://192.168.X.X/<AccountName>/api/...等

When hosted in the production environment, the WebAPI lives on a server that is not exposed externally, hence the various links returned in the OData response such as the @odata.context and @odata.nextLink point to the internal IP address e.g. http://192.168.X.X/<AccountName>/api/... etc.

通过在每个ODataController方法中实现一些逻辑以将内部URL替换为诸如https://account-name.domain.com/api/...之类的外部URL，我已经能够修改Request.ODataProperties().NextLink，但这非常不便，并且只能修复NextLinks.

I've been able to modify the Request.ODataProperties().NextLink by implementing some logic in each and every ODataController method to replace the internal URL with an external URL like https://account-name.domain.com/api/..., but this is very inconvenient and it only fixes the NextLinks.

在OData服务的配置时是否可以通过某种方式设置外部主机名?我看过一个属性Request.ODataProperties().Path，想知道是否可以在config.MapODataServiceRoute("odata", "odata", GetModel());调用中或在GetModel()实现中使用例如ODataConventionModelBuilder设置基本路径?

Is there some way to set an external host name at configuration time of the OData service? I've seen a property Request.ODataProperties().Path and wonder if it's possible to set a base path at the config.MapODataServiceRoute("odata", "odata", GetModel()); call, or in the GetModel() implementation using for instance the ODataConventionModelBuilder?

更新:到目前为止，我想出的最好的解决方案是创建一个覆盖Initialize方法的BaseODataController并检查Request.RequestUri.Host.StartsWith("beginning-of-known-internal-IP-address")是否存在，然后执行RequestUri像这样重写:

UPDATE: The best solution I've come up with so far, is to create a BaseODataController that overrides the Initialize method and checks whether the Request.RequestUri.Host.StartsWith("beginning-of-known-internal-IP-address") and then do a RequestUri rewrite like so:

var externalAddress = ConfigClient.Get().ExternalAddress;  // e.g. https://account-name.domain.com
var account = ConfigClient.Get().Id;  // e.g. AccountName
var uriToReplace = new Uri(new Uri("http://" + Request.RequestUri.Host), account);
string originalUri = Request.RequestUri.AbsoluteUri;
Request.RequestUri = new Uri(Request.RequestUri.AbsoluteUri.Replace(uriToReplace.AbsoluteUri, externalAddress));
string newUri = Request.RequestUri.AbsoluteUri;
this.GetLogger().Info($"Request URI was rewritten from {originalUri} to {newUri}");

这完美地修复了所有控制器的@odata.nextLink URL，但是由于某些原因，@odata.context URL仍然具有AccountName部分(例如，

This perfectly fixes the @odata.nextLink URLs for all controllers, but for some reason the @odata.context URLs still get the AccountName part (e.g. https://account-name.domain.com/AccountName/api/odata/$metadata#ControllerName) so they still don't work.

推荐答案

重写RequestUri足以影响@odata.nextLink值，因为 UrlHelper ，这是某种方式引用原始请求URI中的路径. (因此，您在@odata.context链接中看到了AccountName.我已经在代码中看到了此行为，但是我无法跟踪缓存的URI路径的来源.)

Rewriting the RequestUri is sufficient to affect @odata.nextLink values because the code that computes the next link depends on the RequestUri directly. The other @odata.xxx links are computed via a UrlHelper, which is somehow referencing the path from the original request URI. (Hence the AccountName you see in your @odata.context link. I've seen this behavior in my code, but I haven't been able to track down the source of the cached URI path.)

我们可以通过创建一个CustomUrlHelper类来即时重写OData链接，而不是重写RequestUri.新的GetNextPageLink方法将处理@odata.nextLink重写，而Link方法重写将处理所有其他重写.

Rather than rewrite the RequestUri, we can solve the problem by creating a CustomUrlHelper class to rewrite OData links on the fly. The new GetNextPageLink method will handle @odata.nextLink rewrites, and the Link method override will handle all other rewrites.

public class CustomUrlHelper : System.Web.Http.Routing.UrlHelper
{
    public CustomUrlHelper(HttpRequestMessage request) : base(request)
    { }

    // Change these strings to suit your specific needs.
    private static readonly string ODataRouteName = "ODataRoute"; // Must be the same as used in api config
    private static readonly string TargetPrefix = "http://localhost:8080/somePathPrefix"; 
    private static readonly int TargetPrefixLength = TargetPrefix.Length;
    private static readonly string ReplacementPrefix = "http://www.contoso.com"; // Do not end with slash

    // Helper method.
    protected string ReplaceTargetPrefix(string link)
    {
        if (link.StartsWith(TargetPrefix))
        {
            if (link.Length == TargetPrefixLength)
            {
                link = ReplacementPrefix;
            }
            else if (link[TargetPrefixLength] == '/')
            {
                link = ReplacementPrefix + link.Substring(TargetPrefixLength);
            }
        }

        return link;
    }

    public override string Link(string routeName, IDictionary<string, object> routeValues)
    {
        var link = base.Link(routeName, routeValues);

        if (routeName == ODataRouteName)
        {
            link = this.ReplaceTargetPrefix(link);
        }

        return link;
    }

    public Uri GetNextPageLink(int pageSize)
    {
        return new Uri(this.ReplaceTargetPrefix(this.Request.GetNextPageLink(pageSize).ToString()));
    }
}

使用基本控制器类的Initialize方法连接CustomUrlHelper.

Wire-up the CustomUrlHelper in the Initialize method of a base controller class.

public abstract class BaseODataController : ODataController
{
    protected abstract int DefaultPageSize { get; }

    protected override void Initialize(System.Web.Http.Controllers.HttpControllerContext controllerContext)
    {
        base.Initialize(controllerContext);

        var helper = new CustomUrlHelper(controllerContext.Request);
        controllerContext.RequestContext.Url = helper;
        controllerContext.Request.ODataProperties().NextLink = helper.GetNextPageLink(this.DefaultPageSize);
    }

在上面请注意，页面大小对于给定控制器类中的所有操作都是相同的.您可以通过将ODataProperties().NextLink的分配移动到特定操作方法的主体来解决此限制，如下所示:

Note in the above that the page size will be the same for all actions in a given controller class. You can work around this limitation by moving the assignment of ODataProperties().NextLink to the body of a specific action method as follows:

var helper = this.RequestContext.Url as CustomUrlHelper;
this.Request.ODataProperties().NextLink = helper.GetNextPageLink(otherPageSize);

这篇关于覆盖Webapi OData链接的主机的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！