Allow custom values from JS to be returned from renderToString in SpaServices #384
Comments
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Good news - we have this feature already :) See under the subheading Passing data from server-side to client-side code on the docs here: https://github.com/aspnet/JavaScriptServices/tree/dev/src/Microsoft.AspNetCore.SpaServices#3-supplying-javascript-code-to-perform-prerendering |
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Hi Steve, what I actually want is Passing data from JS server-side to .NET server-side code . Sort of like the reverse of asp-prerender-data. This is useful for pre-rendering meta-data such as page title server side, before the client gets it. I quickly skimmed the source and didn't find any functionality like it. Is this functionality available? If not, I'm happy to submit a PR based on the ViewBag implementation I outline above. Thanks |
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@loune, the |
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Thanks for the suggestion @SteveSandersonMS. Does this mean I can't use |
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@SteveSandersonMS This is the similar situation I was trying to figure out as well for the template. Currently we're not rendering I have solved the issue of grabbing all the needed meta data/tags from the Application getting serialized, now I just need to get it to go -outside- of that, and actually effect the _Layout page, etc. I'm assuming ViewBag is best suitable for this, but I don't think it can be accomplished just yet? |
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@MarkPieszak It can be accomplished already, but it takes more code than I'd prefer. For example, you can have an MVC controller like this: public async Task<IActionResult> Index(
[FromServices] IHostingEnvironment hostEnv,
[FromServices] INodeServices nodeServices)
{
// Instead of using the asp-prerender-module tag helper, we'll invoke Prerenderer.RenderToString
// in the controller so we can get additional info to pass to the view
var requestFeature = Request.HttpContext.Features.Get<IHttpRequestFeature>();
var unencodedPathAndQuery = requestFeature.RawTarget;
var unencodedAbsoluteUrl = $"{Request.Scheme}://{Request.Host}{unencodedPathAndQuery}";
var prerenderResult = await Prerenderer.RenderToString(
hostEnv.ContentRootPath,
nodeServices,
new JavaScriptModuleExport("ClientApp/dist/main-server"),
unencodedAbsoluteUrl,
unencodedPathAndQuery,
/* custom data parameter */ null,
/* timeout milliseconds */ 15*1000,
Request.PathBase.ToString()
);
ViewData["SpaHtml"] = prerenderResult.Html;
ViewData["Title"] = prerenderResult.Globals["pageTitle"];
return View();
}That lets you pass the prerender result data to the view where it can be used in arbitrary ways (e.g., to set the page title). I recognise that this is non-obvious, and even when you can see the code that works, it's not too nice to be embedding that sort of logic (e.g., the We could make this much more convenient, though. I've filed an issue to track this: #607 |
I think a useful feature would be to allow values other than the rendered html to be passed back from the renderToString JavaScript context to the .NET world. For example, the JS might provide a page title, which could then be rendered by the razor layout page. I think the ViewBag would be a good place for this data sharing.
For example, in boot-server.tsx
And in _Layout.cshtml
Keen for thoughts and comments.
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