英文:
How to convert (type *bytes.Buffer) to use as []byte in argument to w.Write
问题
我正在尝试从服务器返回一些 JSON，但是在以下代码中遇到了这个错误：
cannot use buffer (type *bytes.Buffer) as type []byte in argument to w.Write
通过一些搜索，我找到了这个 Stack Overflow 的答案，但是无法使其工作（请参考带有错误信息的第二段代码示例）。
第一个代码示例：
buffer := new(bytes.Buffer)
for _, jsonRawMessage := range sliceOfJsonRawMessages {
if err := json.Compact(buffer, jsonRawMessage); err != nil {
fmt.Println("error")
}
}
fmt.Println("json returned", buffer) // 这是 JSON
w.Header().Set("Content-Type", contentTypeJSON)
w.Write(buffer) // 错误：cannot use buffer (type *bytes.Buffer) as type []byte in argument to w.Write
第二个代码示例（带有错误）：
cannot use foo (type *bufio.Writer) as type *bytes.Buffer in argument to json.Compact
cannot use foo (type *bufio.Writer) as type []byte in argument to w.Write
var b bytes.Buffer
foo := bufio.NewWriter(&b)
for _, d := range t.J {
if err := json.Compact(foo, d); err != nil {
fmt.Println("error")
}
}
w.Header().Set("Content-Type", contentTypeJSON)
w.Write(foo)
英文:
I'm trying to return some json back from the server but get this error with the following code
cannot use buffer (type *bytes.Buffer) as type []byte in argument to w.Write
With a little googling, I found this SO answer but couldn't get it to work (see second code sample with error message)
1st code sample
buffer := new(bytes.Buffer)
for _, jsonRawMessage := range sliceOfJsonRawMessages{
if err := json.Compact(buffer, jsonRawMessage); err != nil{
fmt.Println("error")
}
}
fmt.Println("json returned", buffer)//this is json
w.Header().Set("Content-Type", contentTypeJSON)
w.Write(buffer)//error: cannot use buffer (type *bytes.Buffer) as type []byte in argument to w.Write
2nd code sample with error
cannot use foo (type *bufio.Writer) as type *bytes.Buffer in argument to json.Compact
cannot use foo (type *bufio.Writer) as type []byte in argument to w.Write
var b bytes.Buffer
foo := bufio.NewWriter(&b)
for _, d := range t.J{
if err := json.Compact(foo, d); err != nil{
fmt.Println("error")
}
}
w.Header().Set("Content-Type", contentTypeJSON)
w.Write(foo)
答案1
得分: 75
Write需要一个[]byte（字节切片），而你有一个*bytes.Buffer（指向缓冲区的指针）。
你可以使用Buffer.Bytes()从缓冲区获取数据，并将其传递给Write()：
_, err = w.Write(buffer.Bytes())
...或者使用Buffer.WriteTo()将缓冲区内容直接复制到Writer：
_, err = buffer.WriteTo(w)
使用bytes.Buffer并不是必需的。json.Marshal()直接返回一个[]byte：
var buf []byte
buf, err = json.Marshal(thing)
_, err = w.Write(buf)
英文:
Write requires a []byte (slice of bytes), and you have a *bytes.Buffer (pointer to a buffer).
You could get the data from the buffer with Buffer.Bytes() and give that to Write():
_, err = w.Write(buffer.Bytes())
...or use Buffer.WriteTo() to copy the buffer contents directly to a Writer:
_, err = buffer.WriteTo(w)
Using a bytes.Buffer is not strictly necessary. json.Marshal() returns a []byte directly:
var buf []byte
buf, err = json.Marshal(thing)
_, err = w.Write(buf)
答案2
得分: 10
这是我解决问题的方法：
readBuf, _ := ioutil.ReadAll(jsonStoredInBuffVariable)
这段代码将从缓冲变量中读取，并输出 []byte 值。
英文:
This is how I solved my problem
readBuf, _ := ioutil.ReadAll(jsonStoredInBuffVariable)
This code will read from the buffer variable and output []byte value
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