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Add <head> and <body> Tag Helpers #5728
Comments
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@jbagga please set up a mtg with me, @NTaylorMullen @DamianEdwards (required), and @davidfowl (optional) to figure this out. |
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Here's a straw-man for us to start from that I just hacked together that works. The scenario at the end is the Application Insights SDK injecting the client-side analytics JavaScript without anything needing to be in [HtmlTargetElement("head")]
[EditorBrowsable(EditorBrowsableState.Never)]
public class HeadTagHelper : TagHelper
{
private readonly IList<IHeadTagHelper> _processors;
public HeadTagHelper(IEnumerable<IHeadTagHelper> processors)
{
_processors = processors.OrderBy(p => p.Order).ToList();
}
public override void Init(TagHelperContext context)
{
foreach (var processor in _processors)
{
processor.Init(context);
}
}
public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
foreach (var processor in _processors)
{
await processor.ProcessAsync(context, output);
}
}
}
[HtmlTargetElement("body")]
[EditorBrowsable(EditorBrowsableState.Never)]
public class BodyTagHelper : TagHelper
{
private readonly IList<IBodyTagHelper> _processors;
public BodyTagHelper(IEnumerable<IBodyTagHelper> processors)
{
_processors = processors.OrderBy(p => p.Order).ToList();
}
public override void Init(TagHelperContext context)
{
foreach (var processor in _processors)
{
processor.Init(context);
}
}
public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
foreach (var processor in _processors)
{
await processor.ProcessAsync(context, output);
}
}
}
public interface IHeadTagHelper
{
int Order { get; }
void Init(TagHelperContext context);
Task ProcessAsync(TagHelperContext context, TagHelperOutput output);
}
public interface IBodyTagHelper
{
int Order { get; }
void Init(TagHelperContext context);
Task ProcessAsync(TagHelperContext context, TagHelperOutput output);
}
public class AppInsightsHeadTagHelper : IHeadTagHelper
{
private readonly string _js;
public AppInsightsHeadTagHelper(JavaScriptSnippet appInsightsJs)
{
_js = appInsightsJs.FullScript;
}
public int Order => 1;
public void Init(TagHelperContext context)
{
}
public Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
output.PostContent.AppendHtml("<script>console.log('This was injected!!');</script>");
output.PostContent.AppendHtml(_js);
return Task.CompletedTask;
}
}
public static class WebHostExtensions
{
public static IWebHostBuilder UseApplicationInsights2(this IWebHostBuilder builder) => builder
.UseApplicationInsights()
.ConfigureServices(services => services
.AddSingleton<IHeadTagHelper, AppInsightsHeadTagHelper>());
} |
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Very nice. So given this code, which seems to be fine, what design questions do we actually have? |
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We should discuss naming and enumerate some more scenarios to ensure this covers what we want. Also, what config, options, logging, etc. we might want. |
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Idea to make this more generic: public interface ITagHelperComponent
{
bool AppliesTo(TagHelperContext context);
int Order { get; }
void Init(TagHelperContext context);
Task ProcessAsync(TagHelperContext context, TagHelperOutput output);
}
[HtmlTargetElement("body")]
[HtmlTargetElement("head")]
public class BodyHeadTagHelper : TagHelperComponentTagHelper
{
}
public abstract class TagHelperComponentTagHelper : TagHelper
{
private readonly IList<ITagHelperComponent> _components;
public TagHelperComponentTagHelper(IEnumerable<ITagHelperComponent> components)
{
_components = components.OrderBy(p => p.Order).ToList();
}
public override void Init(TagHelperContext context)
{
foreach (var component in _components)
{
if (component.AppliesTo(context))
{
component.Init(context);
}
}
}
public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
foreach (var component in _components)
{
if (component.AppliesTo(context))
{
await component.ProcessAsync(context, output);
}
}
}
}
public class AppInsightsHeadTagHelperComponent : ITagHelperComponent
{
private readonly string _js;
public AppInsightsHeadTagHelperComponent(JavaScriptSnippet appInsightsJs)
{
_js = appInsightsJs.FullScript;
}
public bool AppliesTo(TagHelperContext context) => string.Equals("head", context.TagName, StringComparison.OrdinalIgnoreCase);
public int Order => 1;
public void Init(TagHelperContext context)
{
}
public Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
output.PostContent.AppendHtml("<script>console.log('This was injected!!');</script>");
output.PostContent.AppendHtml(_js);
return Task.CompletedTask;
}
} |
This was referenced Mar 4, 2017
This was referenced Mar 8, 2017
jbagga
added a commit
to aspnet/Razor
that referenced
this issue
Mar 24, 2017
Addresses aspnet/Mvc#5728
jbagga
added a commit
to aspnet/Razor
that referenced
this issue
Mar 29, 2017
|
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They need to allow components in DI to add stuff to be rendered in the
<head>and/or<body>elements. Maybe viaTagHelperInitializers? Need to consider support for ordering too.The text was updated successfully, but these errors were encountered: