Firebase Facebook登录检查用户是否存在 [英] Firebase Facebook login check if user exist

问题描述

我有一个与firebase一起工作的facebook登录系统，但是我想检查用户是否存在于我的firebase上（我不想添加它，只想确定他是否存在，因为我想将用户重定向到另一个页面来完成它的个人资料，一旦完成，我想把它发送到firebase）。

我只需要检查用户是否存在我的数据库。这是我尝试的代码，但它返回nil错误，并自动将用户添加到firebase。

  let credential = FIRFacebookAuthProvider.credentialWithAccessToken （FBSDKAccessToken.currentAccessToken（）。tokenString）
 
 
 FIRAuth.auth（）？。signInWithCredential（凭证）{（user，error）in 
 // ... 
 
 
 $ / code $ / $ p 
 
解决方案
 code> reauthenticateWithCredential 方法检查用户是否存在。 
 
 
检查此文档，section  - >重新认证用户
 $ p $  let user = FIRAuth.auth（）？currentUser 
 var凭证：FIRAuthCredential 
 
提示用户重新提供登录凭据
 
用户？.reauthenticateWithCredential（凭证）{
中的错误，如果让错误=错误{
 //发生错误。 
} else {
 //用户重新认证。 
 
 
 
 
 
 
如果用户重新认证成功意味着用户存在... 
 
I have an facebook login system which works with firebase but I want to check if user exist on my firebase (i don't want to add it, just want to make sure if he exist because I want to redirect user to another page to complete its profile, once its done I'll want to send it to firebase).

I just need to check if user exist on my db. Here is the code that I try but it returns nil error and it automatically add user to firebase.
let credential = FIRFacebookAuthProvider.credentialWithAccessToken(FBSDKAccessToken.currentAccessToken().tokenString)


FIRAuth.auth()?.signInWithCredential(credential) { (user, error) in
        // ... 

}

解决方案
You can use reauthenticateWithCredential method to check user is exist or not.

Check this Doc. , section -> Re-authenticate a user
let user = FIRAuth.auth()?.currentUser
var credential: FIRAuthCredential

// Prompt the user to re-provide their sign-in credentials

user?.reauthenticateWithCredential(credential) { error in
  if let error = error {
    // An error happened.
  } else {
    // User re-authenticated.
  }
}
If user re-authenticated successfully that means user is existed...

                        
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