# Net Core 使用google登入(openId 套件)
###### tags: `google` `.net core` `openId` `第三方登入`

#### 在Google中設定服務

設定連結 : https://console.cloud.google.com/apis/dashboard?hl=zh-tw

需要套件
Microsoft.AspNetCore.Authentication.OpenIdConnect
Microsoft.AspNetCore.Identity.EntityFrameworkCore(for EntityFrameworkStores)

##### Startup

        services.AddIdentityCore<IdentityUser>()
            .AddRoles<IdentityRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddSignInManager()
            .AddDefaultTokenProviders();


        services.AddAuthentication(options =>
        {
           options.DefaultScheme = "Google";
        }).AddOpenIdConnect(
            authenticationScheme: "Google",
            displayName: "Google",
            options =>
            {
                options.Authority = "https://accounts.google.com/";
                options.ClientId = "";    //services id
                options.CallbackPath = "/signin-google";
                // Add email scope
                options.Scope.Add("email");
            });

#### Controller

private readonly SignInManager<IdentityUser> _signInManager;
public AccountController( SignInManager<IdentityUser> signInManager)
{
//需要先DI signInManager
_signInManager = signInManager;
}

[HttpGet]
[AllowAnonymous]
[Route("~/signin-google")]
public async Task<IActionResult> ExternalLoginCallback()
{
var result = await HttpContext.AuthenticateAsync("Google");
if (!result.Succeeded)
{
return RedirectToAction("Login", "Account"); ;
}
return RedirectToAction("Index", "Home");
}
[HttpGet]

public IActionResult ExternalLogin()
{
var redirectUrl = Url.Action(nameof(ExternalLoginCallback)); //以此方式設定路徑比較不會有奇怪的問題
var properties = _signInManager.ConfigureExternalAuthenticationProperties("Google", redirectUrl);
return Challenge(properties, "Google"); //轉址到redirecUrl
}

#### View

<div class="d-flex justify-content-center mgB20">
<button type="button" class="btn btn-loginType btn-transition" onclick="location.href='@Url.Action("ExternalLogin","Parent",new { @ViewBag.SchoolId,type=1 })'">
<img src="~/img/image_google.png">
<span>透過 Google 登入</span>
</button>
</div>