🐛 [Bug]: agent.Struct fails to unmarshal response since 2.33.0

teemukataja commented 2 years ago

Bug Description

agent.Struct() raises a null pointer exception.
agent.Struct() works in 2.32.0, but stopped working after 2.33.0, including the latest release 2.38.1.

How to Reproduce

Working version with 2.32.0

set fiber version to 2.32.0 in go.mod
run go mod tidy
run script
response is successfully parsed

Broken version 2.33.0-2.38.1

set fiber version to anything after 2.33.0 in go.mod
run go mod tidy
run script
null pointer exception is raised

Expected Behavior

JSON response is unmarshalled into struct.

Fiber Version

2.33.0-2.38.1

Code Snippet (optional)

package main

import (
    "fmt"

    "github.com/gofiber/fiber/v2"
)

type response struct {
    Title string `json:"title,omitempty"`
}

func main() {

    agent := fiber.AcquireAgent()
    defer agent.ConnectionClose()
    request := agent.Request()
    request.Header.SetMethod("GET")
    request.SetRequestURI("https://jsonplaceholder.typicode.com/todos/1")

    _ = agent.Parse()

    var r response
    _, _, _ = agent.Struct(&r)  // exception raised here

    fmt.Println(r)
}

$ go run cmd/main.go
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x668e38]

goroutine 1 [running]:
github.com/gofiber/fiber/v2.(*Agent).Struct(0xc0000fa000, {0x680720, 0xc000013180})
    /home/go/1.18.6/pkg/mod/github.com/gofiber/fiber/v2@v2.38.1/client.go:829 +0xf8
main.main()
    /home/go/1.18.6/src/request-test/cmd/main.go:24 +0x1c5

Checklist:

[X] I agree to follow Fiber's Code of Conduct.
[X] I have checked for existing issues that describe my problem prior to opening this one.
[X] I understand that improperly formatted bug reports may be closed without explanation.

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teemukataja commented 2 years ago

I have a workaround solution by using agent.Bytes instead and unmarshalling manually:

var r response
_, body, _ := agent.Bytes()
_ = json.Unmarshal(body, &r)

li-jin-gou commented 2 years ago

use a.JSONDecoder(json.Unmarshal).Struct(&r)

ReneWerner87 commented 2 years ago

@teemukataja thanks for the hint, fixed it in the pull request #2137

will be in the next release

until then you have to set the default decoder by hand https://github.com/gofiber/fiber/issues/2134#issuecomment-1265283424

gofiber / fiber