I've been scouring the web and pouring over the System.Web assemblies with Reflect to try and figure out the best way to render a partial view to a string. It seems there are several solutions out there, but many of them seemed complicated, hackalicious, or
both. I then came across a post which had a fairly elegant and straightfoward solution--I tweaked it a little bit, and came up with this. Hopefully it will be useful to some others! I thought I would post it here:
There is an overload that takes a raw object, and assigns it to ViewData.Model -- that way I can just pass in a single object to be used as the model in the partial view. This is what I'm doing. But, if you are going to use the same model as the parent view,
just pass in the complete ViewData object.
namespace fully.qualified.namespace.to.your.extension.classes
{
public static class AtHomeExtensions
{
public static string RenderPartialToString(this HtmlHelper html, string partialView, ViewDataDictionary viewData)
{
UrlHelper urlHelper = new UrlHelper(html.ViewContext.RequestContext);
ViewPage vp = new ViewPage() { ViewData = viewData, ViewContext = html.ViewContext, Url = urlHelper };
Control control = vp.LoadControl(partialView);
vp.Controls.Add(control);
StringBuilder sb = new StringBuilder();
using (StringWriter sw = new StringWriter(sb))
{
using (HtmlTextWriter tw = new HtmlTextWriter(sw))
{
vp.RenderControl(tw);
}
}
return sb.ToString();
}
public static string RenderPartialToString(this HtmlHelper html, string partialView, object model)
{
ViewDataDictionary viewData = new ViewDataDictionary(model);
return RenderPartialToString(html, partialView, viewData);
}
}
}
Remember that in order to use these in your views (e.g., <% string partial = Html.RenderPartialToString(...) %> you will need to put something like <%@ Import Namespace="fully.qualified.namespace.to.your.extension.classes" %>
For your reference, here's the original post that I got this from:
That's really interesting. What are you using this for? I'm just trying to think of situations where I would need to assign a parial view output to a string.
That's really interesting. What are you using this for? I'm just trying to think of situations where I would need to assign a parial view output to a string.
I've got a calendar with events on them. When a user clicks on a particular event, I want to popup a dialog with more info. I've got a partial view that generates the HTML displayed in that dialog, and I'm using jQuery to turn it into a nifty little popup
window (see demo here: http://jqueryui.com/demos/dialog/)
Anyway, to make a long story short, I've got the HTML, and I need to then wrap it in some container <div>s and pass the whole long block to a JavaScript function. In order to do that, I really need some way to get at the HTML that the partial view is generating,
rather than just writing it directly to the output stream. I'm sure you could do it by cleverly constructing the output stream, but this way just feels much better :-)
But the use case essentially boils down to this--you want to get the partial view output and pass it as an argument to some other bit of code.
Hmm. I've done somethign very similar with a jquery dialog and my action method was actually fairly straightforwad
public ActionResult GetJqueryDialog(){
return View("partialViewName");
}
My jquery code contains an Ajax call to GetJqueryDialog(), the result is automatically appended to the dialog at runtime. The partial view is automatically returned as a string. So while your method is pretty cool, I think it may be overkill.
That would work, but you've now got multiple calls for content (one for the initial page load, and one for each dialog). I wanted to send everything to the client on the first pass. Especially on a slow connection, splitting things across multiple requests
can really make the site feel slow. -Josh
Also, if you're trying to pass the partial view's rendered contents to something server side, an AJAX call to a specific action really makes no sense.
For instance, let's say you've got a confirmation page that includes a partial view that shows the user a "Thank you for ordering!" message, along with a summary of their purchase.
That's great--now let's say you want to email that to them as well. You need the partial view rendered out as a string so you can put it in the message body of your email.
What will happen is that "blogPostAsString" will he the title in an <h1> block, but the body, which is rendered by PostBody.ascx, will get written directly to the output stream.
If you control the user controls you're working, you can use the following workaround:
Basically, you have to avoid using Html.RenderPartial anywhere, and instead use Html.RenderPartialToString everywhere. Which, is really clunky... and impossible if you're using user controls that you can't, or don't want to modify.
Hopefully the ASP.NET team will give us a real solution for this soon. I could really use it!
Yet another drawback--performance. I've found that rendering a large number of controls to strings noticably slows down the page generation time. I've got one rendering a few dozen controls to a string, and it takes about 2 seconds for the page to generate.
So now I *really* hope we get a fix for this soon!
jbeall
Participant
813 Points
274 Posts
Rendering a partial view to a string -- my solution
Jun 22, 2009 03:26 PM|LINK
Hi All,
I've been scouring the web and pouring over the System.Web assemblies with Reflect to try and figure out the best way to render a partial view to a string. It seems there are several solutions out there, but many of them seemed complicated, hackalicious, or both. I then came across a post which had a fairly elegant and straightfoward solution--I tweaked it a little bit, and came up with this. Hopefully it will be useful to some others! I thought I would post it here:
There is an overload that takes a raw object, and assigns it to ViewData.Model -- that way I can just pass in a single object to be used as the model in the partial view. This is what I'm doing. But, if you are going to use the same model as the parent view, just pass in the complete ViewData object.
namespace fully.qualified.namespace.to.your.extension.classes { public static class AtHomeExtensions { public static string RenderPartialToString(this HtmlHelper html, string partialView, ViewDataDictionary viewData) { UrlHelper urlHelper = new UrlHelper(html.ViewContext.RequestContext); ViewPage vp = new ViewPage() { ViewData = viewData, ViewContext = html.ViewContext, Url = urlHelper }; Control control = vp.LoadControl(partialView); vp.Controls.Add(control); StringBuilder sb = new StringBuilder(); using (StringWriter sw = new StringWriter(sb)) { using (HtmlTextWriter tw = new HtmlTextWriter(sw)) { vp.RenderControl(tw); } } return sb.ToString(); } public static string RenderPartialToString(this HtmlHelper html, string partialView, object model) { ViewDataDictionary viewData = new ViewDataDictionary(model); return RenderPartialToString(html, partialView, viewData); } } }Remember that in order to use these in your views (e.g., <% string partial = Html.RenderPartialToString(...) %> you will need to put something like <%@ Import Namespace="fully.qualified.namespace.to.your.extension.classes" %>
For your reference, here's the original post that I got this from:
http://thriftybliss.spaces.live.com/blog/cns!58DA805F37F31F20!170.entry
CodeHobo
All-Star
18647 Points
2647 Posts
Re: Rendering a partial view to a string -- my solution
Jun 22, 2009 08:12 PM|LINK
That's really interesting. What are you using this for? I'm just trying to think of situations where I would need to assign a parial view output to a string.
Blog | Twitter : @Hattan
jbeall
Participant
813 Points
274 Posts
Re: Rendering a partial view to a string -- my solution
Jun 22, 2009 08:45 PM|LINK
I've got a calendar with events on them. When a user clicks on a particular event, I want to popup a dialog with more info. I've got a partial view that generates the HTML displayed in that dialog, and I'm using jQuery to turn it into a nifty little popup window (see demo here: http://jqueryui.com/demos/dialog/)
Anyway, to make a long story short, I've got the HTML, and I need to then wrap it in some container <div>s and pass the whole long block to a JavaScript function. In order to do that, I really need some way to get at the HTML that the partial view is generating, rather than just writing it directly to the output stream. I'm sure you could do it by cleverly constructing the output stream, but this way just feels much better :-)
But the use case essentially boils down to this--you want to get the partial view output and pass it as an argument to some other bit of code.
-Josh
CodeHobo
All-Star
18647 Points
2647 Posts
Re: Rendering a partial view to a string -- my solution
Jun 22, 2009 09:15 PM|LINK
Hmm. I've done somethign very similar with a jquery dialog and my action method was actually fairly straightforwad
public ActionResult GetJqueryDialog(){ return View("partialViewName"); }My jquery code contains an Ajax call to GetJqueryDialog(), the result is automatically appended to the dialog at runtime. The partial view is automatically returned as a string. So while your method is pretty cool, I think it may be overkill.
Blog | Twitter : @Hattan
jbeall
Participant
813 Points
274 Posts
Re: Rendering a partial view to a string -- my solution
Jun 22, 2009 09:39 PM|LINK
jbeall
Participant
813 Points
274 Posts
Re: Rendering a partial view to a string -- my solution
Jun 22, 2009 09:43 PM|LINK
Also, if you're trying to pass the partial view's rendered contents to something server side, an AJAX call to a specific action really makes no sense.
For instance, let's say you've got a confirmation page that includes a partial view that shows the user a "Thank you for ordering!" message, along with a summary of their purchase.
That's great--now let's say you want to email that to them as well. You need the partial view rendered out as a string so you can put it in the message body of your email.
CodeHobo
All-Star
18647 Points
2647 Posts
Re: Rendering a partial view to a string -- my solution
Jun 22, 2009 09:48 PM|LINK
That makes total sense. Thanks for sharing, I'm definitely bookmarking this thread cause I know I'll need something like this soon :).
Blog | Twitter : @Hattan
jbeall
Participant
813 Points
274 Posts
Re: Rendering a partial view to a string -- my solution
Jul 24, 2009 08:05 PM|LINK
Significant drawback to this method--it won't work properly if the control you're rendering to a string, also renders user controls.
Those will be written directly to the output stream. For instance, consider the following sample scenario:
string blogPostAsString = Html.RenderPartialToString("PostUserControl",Post);
Now, in PostUserControl.ascx, you might have:
<h1><%= Post.Title %></h1>
<% Html.RenderPartial("PostBody",Post) %>
What will happen is that "blogPostAsString" will he the title in an <h1> block, but the body, which is rendered by PostBody.ascx, will get written directly to the output stream.
If you control the user controls you're working, you can use the following workaround:
<h1><%= Post.Title %></h1>
<%= Html.RenderPartialToString("PostBody",Post) %>
Basically, you have to avoid using Html.RenderPartial anywhere, and instead use Html.RenderPartialToString everywhere. Which, is really clunky... and impossible if you're using user controls that you can't, or don't want to modify.
Hopefully the ASP.NET team will give us a real solution for this soon. I could really use it!
-Josh
jbeall
Participant
813 Points
274 Posts
Re: Rendering a partial view to a string -- my solution
Jul 30, 2009 03:42 PM|LINK
Yet another drawback--performance. I've found that rendering a large number of controls to strings noticably slows down the page generation time. I've got one rendering a few dozen controls to a string, and it takes about 2 seconds for the page to generate.
So now I *really* hope we get a fix for this soon!
-Josh