Ruby on rails 颤振无法仅正确连接到Rails API

好了，伙计们，这是我的问题

我只有一个标准的Rails5API设置

我的用户控制器几乎是标准的：

# frozen_string_literal: true

class UsersController < ApplicationController
  before_action :set_user, only: %i[show update destroy]

  # GET /users
  def index
    @users = User.all

    render json: @users
  end

  # GET /users/1
  def show
    render json: @user
  end

  # POST /users
  def create
    @user = User.new(user_params)


    if @user.save
      render json: @user, status: :created, location: @user
      UserNotifierMailer.send_signup_email(@user).deliver      
    else
      render json: @user.errors, status: :unprocessable_entity
    end
  end

  # PATCH/PUT /users/1
  def update
    if @user.update(user_params)
      render json: @user
    else
      render json: @user.errors, status: :unprocessable_entity
    end
  end

  # DELETE /users/1
  def destroy
    @user.destroy
  end

  private

  # Use callbacks to share common setup or constraints between actions.
  def set_user
    @user = User.find(params[:id])
  end

  # Only allow a trusted parameter "white list" through.
  def user_params
    params.require(:user).permit(:username, :password, :email)
  end
end

但是当我这样做的时候，我在颤振应用程序中得到了一个错误，就像我丢失了一个用户参数，尽管当我打印出来时，它显示了确切的结构，但我得到了这个。

在这种情况下，请求甚至不会被激发，因此服务器不会被击中

但是，如果我尝试在loginUser方法中执行json.encodebody，则服务器的响应是：

当然，弗利特抱怨：

---

我做错了什么？

好的，我确实找到了一个问题和解决方案

出于某种奇怪的原因，Rails要求数据以内容类型显式发布：application/json

因此，还需要设置请求头，并将它们传递到http.post方法中

---

Rails接收的参数必须是{user:{id:…，name:…}格式，您现在发送的可能是{id:…，name:…}。@SebastianPalma感谢您的提示。这不是问题，而是请求头。我看到了很多响应，但这个头就是问题所在！谢谢7个小时后，我收到了你们的回复并解决了问题。

import 'dart:convert';
import 'package:http/http.dart' as http;

class HeadUser {
  User _user;

  HeadUser({User user}) {
    this._user = user;
  }

  HeadUser.fromJson(Map<String, dynamic> json) {
    _user = json['user'] != null ? new User.fromJson(json['user']) : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this._user != null) {
      data['user'] = this._user.toJson();
    }
    return data;
  }
}

class User {
  String _username;
  String _email;
  String _password;
  int _id;
  DateTime _createdAt;
  DateTime _updatedAt;

  User({int id, DateTime createdAt, DateTime updatedAt, String username, String email, String password}) {
    this._username = username;
    this._email = email;
    this._password = password;
    this._id = id;
    this._createdAt = createdAt;
    this._updatedAt = updatedAt;
  }

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
    id: json['id'],
    username: json['username'],
    email: json['email'],
    createdAt: json['created_at'],
    updatedAt: json['updated_at'],
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['username'] = this._username;
    data['email'] = this._email;
    data['password'] = this._password;
    return data;
  }
}

Future<HeadUser> loginUser(String url, {Map body}) async {
  return http.post(url, body: body).then((http.Response response) {
    final int statusCode = response.statusCode;
    if (statusCode < 200 || statusCode > 400 || statusCode == null) {
      throw new Exception("Error while posting data");
    }
    return HeadUser.fromJson(json.decode(response.body));
  });

}

 onPressed: () async {
                          if (_formKey.currentState.validate())
                          {
                            HeadUser usr = new HeadUser(user: User(
                              email: this.emailEditingController.text.trim(),
                              password: this.passwordEditingController.text.trim(),
                              username: this.usernameEditingController.text.trim()
                            ));


                            HeadUser response = await loginUser(REGISTRATION_URL, body: usr.toJson());

Future<HeadUser> loginUser(String url, {Map body}) async {
  Map<String, String> headers = {"Content-type": "application/json"};
  return http.post(url, headers: headers, body: json.encode(body)).then((http.Response response) {
    final int statusCode = response.statusCode;
    if (statusCode < 200 || statusCode > 400 || statusCode == null) {
      throw new Exception("Error while posting data");
    }
    return HeadUser.fromJson(json.decode(response.body));
  });