Request

An opinionated but extremely easy to use HTTP request client for Go to make JSON request and retrieve the results

Description

With this request package you just need to define the structs or maps/slices that correspond to the JSON request and response body. Together with the parameters like URL, method and headers you can directly execute a request with Do. If the request body is not of type io.Reader already, it will be encoded as JSON. Also the response will be decoded back into the struct or map/slice you provided for the result. Request and response body are optional which means they can be nil.

If the request could be made but the response status code was not 2xx an error of the type HTTPError from the package httperrors will be returned. The same happens if you specified an ExpectedResponseCode and that one was not matched by the actual response.

Example

import (
    "net/http"
    "github.com/fastbill/go-request/v2"
)

type Input struct {
	RequestValue string `json:"requestValue"`
}

type Output struct {
	ResponseValue string `json:"responseValue"`
}

params := request.Params{
    URL:    "https://example.com",
    Method: http.MethodPost,
    Headers: map[string]string{"my-header":"value", "another-header":"value2"},
    Body:   Input{RequestValue: "someValueIn"},
    Query: map[string]string{"key": "value"},
    Timeout: 10 * time.Second,
    ExpectedResponseCode: 201,
}

result := &Output{}
err := request.Do(params, result)

All parameters besides the URL and the Method are optional and can be omitted.

Accessing the response headers

If you need access to the headers of the http response, you can initialize a header map and pass it as a third argument to Do. It will then be populated with the response headers that the server returns.

responseHeaders := http.Header{}
err := request.Do(params, result, responseHeaders)

Using a custom http client

If you want to supply a custom http client to use for the request, you can use DoWithCustomClient. The client needs to be of type *http.Client.

err := request.DoWithCustomClient(params, result)

Retrieving the response as a string

If you want to retrieve the response body as a string, e.g. for debugging or testing purposes, you can use DoWithStringResponse.

result, err := request.DoWithStringResponse(params)

Convenience wrappers

err := request.Get("http://example.com", result)

err := request.Post("http://example.com", Input{RequestValue: "someValueIn"}, result)

Defaults

• All 2xx response codes are treated as success, all other codes lead to an error being returned, if you want to check for a specific response code set ExpectedResponseCode in the parameters
• If an HTTPError is returned it contains the response body as message if there was one
• The request package takes care of closing the response body after sending the request
• The http client does not follow redirects
• The http client timeout is set to 30 seconds, use the Timeout parameter in case you want to define a different timeout for one of the requests
• Accept and Content-Type request header are set to application/json and can be overwritten via the Headers parameter
• The parameters Headers and Query accept a simple map[string]string. If you want to pass http.Header or url.Values instead, wrap them in the provided request.ReformatMap helper function.

Streaming

The package allows the request body (Body property of Params) to be of type io.Reader. That way you can pass on request bodies to other services without parsing them.

Why?

To understand why this package was created have a look at the code that would be the native equivalent of the code shown in the example above.

import (
	"bytes"
	"encoding/json"
	"net/http"
	"time"
)

type Input struct {
	RequestValue string `json:"requestValue"`
}

type Output struct {
	ResponseValue string `json:"responseValue"`
}

buf := &bytes.Buffer{}
err := json.NewEncoder(buf).Encode(&Input{RequestValue: "someValueIn"})
if err != nil {
    return err
}

req, err := http.NewRequest(http.MethodPost, url, buf)
if err != nil {
    return err
}

req.Header.Set("Accept", "application/json")
req.Header.Set("Content-Type", "application/json")
req.Header.Set("my-header", "value")
req.Header.Set("another-header", "value2")

q := req.URL.Query()
q.Add("key", "value")
req.URL.RawQuery = q.Encode()

client := &http.Client{
    Timeout: 30 * time.Second,
    CheckRedirect: func(req *http.Request, via []*http.Request) error {
        return http.ErrUseLastResponse
    },
}

res, err := client.Do(req)
if err != nil {
    return err
}
defer func() {
    err = res.Body.Close()
    // handle err somehow
}()

result := &Output{}
err = json.NewDecoder(res.Body).Decode(result)

This shows the request package saves a lot of boilerplate code. Instead of around 35 lines we just write the 9 lines shown in the example. That way the code is much easier to read and maintain.