github.com/google/martian/v3@v3.3.3/querystring/query_string_modifier.go (about)

     1  // Copyright 2015 Google Inc. All rights reserved.
     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 querystring contains a modifier to rewrite query strings in a request.
    16  package querystring
    17  
    18  import (
    19  	"encoding/json"
    20  	"net/http"
    21  
    22  	"github.com/google/martian/v3"
    23  	"github.com/google/martian/v3/parse"
    24  )
    25  
    26  func init() {
    27  	parse.Register("querystring.Modifier", modifierFromJSON)
    28  }
    29  
    30  type modifier struct {
    31  	key, value string
    32  }
    33  
    34  type modifierJSON struct {
    35  	Name  string               `json:"name"`
    36  	Value string               `json:"value"`
    37  	Scope []parse.ModifierType `json:"scope"`
    38  }
    39  
    40  // ModifyRequest modifies the query string of the request with the given key and value.
    41  func (m *modifier) ModifyRequest(req *http.Request) error {
    42  	query := req.URL.Query()
    43  	query.Set(m.key, m.value)
    44  	req.URL.RawQuery = query.Encode()
    45  
    46  	return nil
    47  }
    48  
    49  // NewModifier returns a request modifier that will set the query string
    50  // at key with the given value. If the query string key already exists all
    51  // values will be overwritten.
    52  func NewModifier(key, value string) martian.RequestModifier {
    53  	return &modifier{
    54  		key:   key,
    55  		value: value,
    56  	}
    57  }
    58  
    59  // modifierFromJSON takes a JSON message as a byte slice and returns
    60  // a querystring.modifier and an error.
    61  //
    62  // Example JSON:
    63  // {
    64  //  "name": "param",
    65  //  "value": "true",
    66  //  "scope": ["request", "response"]
    67  // }
    68  func modifierFromJSON(b []byte) (*parse.Result, error) {
    69  	msg := &modifierJSON{}
    70  
    71  	if err := json.Unmarshal(b, msg); err != nil {
    72  		return nil, err
    73  	}
    74  
    75  	return parse.NewResult(NewModifier(msg.Name, msg.Value), msg.Scope)
    76  }