go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/server/templates/middleware.go (about)

     1  // Copyright 2015 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package templates
    16  
    17  import (
    18  	"fmt"
    19  	"net/http"
    20  
    21  	"go.chromium.org/luci/server/router"
    22  )
    23  
    24  // WithTemplates is middleware that lazily loads template bundle and injects it
    25  // into the context.
    26  //
    27  // Wrapper reply with HTTP 500 if templates can not be loaded. Inner handler
    28  // receives context with all templates successfully loaded.
    29  func WithTemplates(b *Bundle) router.Middleware {
    30  	return func(c *router.Context, next router.Handler) {
    31  		// Note: Use(...) calls EnsureLoaded and initializes b.err inside.
    32  		c.Request = c.Request.WithContext(Use(c.Request.Context(), b, &Extra{
    33  			Request: c.Request,
    34  			Params:  c.Params,
    35  		}))
    36  		if b.err != nil {
    37  			http.Error(c.Writer, fmt.Sprintf("Can't load HTML templates.\n%s", b.err), http.StatusInternalServerError)
    38  			return
    39  		}
    40  		next(c)
    41  	}
    42  }