Custom URL Rewriting - asp.net-core-2.0

Question

I want to rewrite a url which is simple by using the UseRewriter Middleware.
var rewrite = new RewriteOptions()
.AddRedirect("Page1From", "Page1To") // Redirect
.AddRewrite("Page2From", "Page2To", true); // Rewrite
app.UseRewriter(rewrite);
This will have as a result, the url "/Page1From" will be redirected to "Page1To" and the url "Page2From" will display the contents of the "/Page2To" without redirect.
I want to implement the AddRewrite method by using data from database but I only found how to redirect using a custom Rule.
var rewrite = new RewriteOptions()
.AddRedirect("Page1From", "Page1To") // Redirect
.AddRewrite("Page2From", "Page2To", true); // Rewrite
.Add(new MoviesRedirectRule( // Custom Rule
matchPaths: new[] { "/Page3From1", "/Page3From2", "/Page3From3" },
newPath: "/Page3To"));
app.UseRewriter(rewrite);
and the rule is the following:
public class MoviesRedirectRule : IRule
{
private readonly string[] matchPaths;
private readonly PathString newPath;
public MoviesRedirectRule(string[] matchPaths, string newPath)
{
this.matchPaths = matchPaths;
this.newPath = new PathString(newPath);
}
public void ApplyRule(RewriteContext context)
{
var request = context.HttpContext.Request;
// if already redirected, skip
if (request.Path.StartsWithSegments(new PathString(this.newPath)))
{
return;
}
if (this.matchPaths.Contains(request.Path.Value))
{
var newLocation = $"{this.newPath}{request.QueryString}";
var response = context.HttpContext.Response;
response.StatusCode = StatusCodes.Status302Found;
context.Result = RuleResult.EndResponse;
response.Headers[HeaderNames.Location] = newLocation;
}
}
}
This will redirect the following urls:
/Page3From1
/Page3From2
/Page3From3
to /Page3To
I want to create something similar which will not redirect but I want to Rewrite the url so that the url will remain the same but it will display the contents of a specified URL.
Can someone tell me what changes I have to do to the response object in order to make it work?

Answer 1

RewriteRule that is added when you call AddRewrite() just replaces URI parts in request (link to source code):
request.Scheme = scheme;
request.Host = host;
request.Path = pathString;
request.QueryString = query.Add(request.QueryString);
In your case, since you are replacing only Path part, ApplyRule method would be as simple as:
public void ApplyRule(RewriteContext context)
{
var request = context.HttpContext.Request;
if (matchPaths.Contains(request.Path.Value))
{
request.Path = newPath;
context.Result = RuleResult.SkipRemainingRules;
}
}