Question

我在rails 5 api中的会话控制器中一直收到此错误：

undefined method `[]' for nil:NilClass

老实说，我不确定自己做错了什么。这是我的会话控制器的代码（第8行发生错误）：

module Api
class SessionsController < ApplicationController

def new
end

def create
  # The error occurs on this line
  @user = @User.find_by(email: params[:session][:email].downcase)
    if user && user.authenticate(params[:session][:password])
      render :text => user.access_token, status: 200
    else
      render text: "Email and password combination are invalid", status: 422
    end
end


def verify_access_token
  user = User.find_by(access_token: params[:session][:access_token])
    if user
      render text: "verified", status: 200
    else
      render text: "Token failed verification", status: 422
    end
  end

 end
end

这是我的sesssions帮助：

module SessionsHelper
# Logs in the given user.
def log_in(user)
session[:user_id] = user.id
end

# Remembers a user in a persistent session.
# signed creates an encrypted cookie so that's why we use it.
def remember(user)
  user.remember
  cookies.permanent.signed[:user_id] = user.id
  cookies.permanent[:remember_token] = user.remember_token
end

# Returns true if the given user is the current user.
def current_user?(user)
  user == current_user
end

# Returns the current logged-in user (if any).
def current_user
  if (user_id = session[:user_id])
   @current_user ||= User.find_by(id: user_id)
  elsif (user_id = cookies.signed[:user_id])
    user = User.find_by(id: user_id)
    if user && user.authenticated?(cookies[:remember_token])
    log_in user
    @current_user = user
   end
 end
end

# Returns true if the user is logged in, false otherwise.
def logged_in?
 !current_user.nil?
end

# Forgets a persistent session.
def forget(user)
  user.forget
  cookies.delete(:user_id)
  cookies.delete(:remember_token)
end

def log_out
  forget(current_user)
  session.delete(:user_id)
  @current_user = nil
end

# Redirects to stored location (or to the default).
def redirect_back_or(default)
  redirect_to(session[:forwarding_url] || default)
  session.delete(:forwarding_url)
end

# Stores the URL trying to be accessed.
def store_location
  session[:forwarding_url] = request.url if request.get?
end

如果有人可以帮助我找到解决此错误的方法，我们将不胜感激。对于JSON api来说，我是一个新手。

Answer 1

我投注参数[：session]为零。这就是为什么链接哈希键是一个坏主意。

另见Hash＃dig https://ruby-doc.org/core-2.3.0/Hash.html#method-i-dig

（这对我来说是新闻！）

Answer 2

@User不是查找ActiveRecord对象的有效方法。它应该是模型的名称，大写，然后是查找方法。

将@user = @user...更改为@user = User.find_by...，您应该能够正确完成查找。

我喜欢做的一件事就是在有问题的线上方放置一个byebug，然后逐点构建查询＆＃39;在终端，看看我是否能找到我出错的地方。它还可以让你查看参数，以确保那里有东西。

Api中的NoMethodError :: SessionsController #create

2 个答案: