The best way to get a string from a Writer

Question

I have a piece of code that returns a web page using the built-in template system. It accepts a `ResponseWriter` to which the resulting markup is written. I now want to get to the markup as a string and put it in a database in some cases. I factored out a method that accepts a normal `Writer` instead of a `ResponseWriter` and am now trying to get to the written content. Aha - a `Pipe` may be what I need and then I can get the string with `ReadString` from the `bufio` library. But it turns out that the `PipeReader` coming out from the pipe is not compatible with `Reader` (that I would need for the `ReadString` method). W00t. Big surprise. So I could just read into byte[]s using the `PipeReader` but it feels a bit wrong when `ReadString` is there. So what would be the best way to do it? Should I stick with the `Pipe` and read bytes or is there something better that I haven't found in the manual?

Accepted Answer

If your function accepts an io.Writer, you can pass a `*bytes.Buffer` to capture the output.

```
// import "bytes"
buf := new(bytes.Buffer)
f(buf)
buf.String() // returns a string of what was written to it
```

If it requires an http.ResponseWriter, you can use a `*httptest.ResponseRecorder`. A response recorder holds all information that can be sent to a ResponseWriter, but the body is just a `*bytes.Buffer`.

```
// import "net/http/httptest"
r := httptest.NewRecorder()
f(r)
r.Body.String() // r.Body is a *bytes.Buffer
```

The best way to get a string from a Writer

Solution

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