英文:
Get an entity by a key passed via GET parameter
问题
我有
http://localhost:8080/?key=ahFkZXZ-ZGV2LWVkdW5hdGlvbnIOCxIIVXNlckluZm8YLAw
我想问一下如何：
- 解码并将“key”转换为
*datastore.Key - 并使用它来获取一个实体。
谢谢你的帮助！
英文:
I have
http://localhost:8080/?key=ahFkZXZ-ZGV2LWVkdW5hdGlvbnIOCxIIVXNlckluZm8YLAw
I would like to ask on how to:
- Decode and convert the "key" to a
*datastore.Key - And use it to get an entity.
Thanks for your help!
答案1
得分: 6
首先：你应该考虑一下你需要哪些包。由于你试图从URL中读取一个GET值，你可能需要net/http中的一个函数。
特别是：FormValue(key string)返回GET和POST参数。
其次：现在打开appengine/datastore文档，并找到以下功能：
- 将
string解码为*datastore.Key（DecodeKey(encoded string)） - 从数据存储中获取指定的键（Get(c appengine.Context, key *Key, dst interface{})）
现在这是一个非常简单的事情：
func home(w http.Response, r *http.Request) {
c := appengine.NewContext(r)
// 从URL中获取键
keyURL := r.FormValue("key")
// 解码键
key, err := datastore.DecodeKey(keyURL)
if err != nil { // 无法解码键
// 进行一些错误处理
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// 获取键并将其加载到"data"中
var data Data
err = datastore.Get(c, key, data)
if err != nil { // 无法找到实体
// 进行一些错误处理
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
}
英文:
First: You should think about which packages you need this case. Since you're trying to read a GET value from a URL you need probably a function from net/http.
In particular: FormValue(key string) returns GET and POST parameters.
Second: Now open the appengine/datastore documentation and find functions which do the following:
- Decode a
stringto a*datastore.Key(DecodeKey(encoded string)) - Get a specified key from the datastore (Get(c appengine.Context, key *Key, dst interface{}))
Now it's a really easy thing:
func home(w http.Response, r *http.Request) {
c := appengine.NewContext(r)
// Get the key from the URL
keyURL := r.FormValue("key")
// Decode the key
key, err := datastore.DecodeKey(keyURL)
if err != nil { // Couldn't decode the key
// Do some error handling
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// Get the key and load it into "data"
var data Data
err = datastore.Get(c, key, data)
if err != nil { // Couldn't find the entity
// Do some error handling
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
}
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