debug.go

Documentation: google.golang.org/api/examples

     1  // Copyright 2017 Google LLC.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"io"
    11  	"net/http"
    12  	"os"
    13  )
    14  
    15  type logTransport struct {
    16  	rt http.RoundTripper
    17  }
    18  
    19  func (t *logTransport) RoundTrip(req *http.Request) (*http.Response, error) {
    20  	var buf bytes.Buffer
    21  
    22  	os.Stdout.Write([]byte("\n[request]\n"))
    23  	if req.Body != nil {
    24  		req.Body = io.NopCloser(&readButCopy{req.Body, &buf})
    25  	}
    26  	req.Write(os.Stdout)
    27  	if req.Body != nil {
    28  		req.Body = io.NopCloser(&buf)
    29  	}
    30  	os.Stdout.Write([]byte("\n[/request]\n"))
    31  
    32  	res, err := t.rt.RoundTrip(req)
    33  
    34  	fmt.Printf("[response]\n")
    35  	if err != nil {
    36  		fmt.Printf("ERROR: %v", err)
    37  	} else {
    38  		body := res.Body
    39  		res.Body = nil
    40  		res.Write(os.Stdout)
    41  		if body != nil {
    42  			res.Body = io.NopCloser(&echoAsRead{body})
    43  		}
    44  	}
    45  
    46  	return res, err
    47  }
    48  
    49  type echoAsRead struct {
    50  	src io.Reader
    51  }
    52  
    53  func (r *echoAsRead) Read(p []byte) (int, error) {
    54  	n, err := r.src.Read(p)
    55  	if n > 0 {
    56  		os.Stdout.Write(p[:n])
    57  	}
    58  	if err == io.EOF {
    59  		fmt.Printf("\n[/response]\n")
    60  	}
    61  	return n, err
    62  }
    63  
    64  type readButCopy struct {
    65  	src io.Reader
    66  	dst io.Writer
    67  }
    68  
    69  func (r *readButCopy) Read(p []byte) (int, error) {
    70  	n, err := r.src.Read(p)
    71  	if n > 0 {
    72  		r.dst.Write(p[:n])
    73  	}
    74  	return n, err
    75  }
    76
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