TL;DR
Firestore 库不应该在浏览器上下文中运行。它被开发用于服务器端或者可能在管理工具中使用。该库将允许您在 Firestore 中执行所有操作，并且将凭据发送给客户将存在安全风险。
根据您的堆栈跟踪，我假设您使用的是 Google.Cloud.Firestore 库。
不幸的是，这个库被设计成一个“server client library”。用于服务器端的客户端库。
这些“服务器客户端库”的设计不同于“mobile/web client libraries”。
移动/网络库将使用 Firebase 的身份验证（用户名/密码、Facebook 等），并且安全模型将应用于该用户上下文。
服务器库基本上让您可以访问所有内容。
现在您遇到的问题是由 Blazor 不支持此 SDK 引起的。
首先，SDK 所依赖的 GOOGLE_APPLICATION_CREDENTIALS 环境变量在 Blazor 应用程序中不可用。
如果该文件可用，则无法从浏览器沙箱中访问该文件。
您可以通过使用FirestoreDbBuilder 并像这样手动设置JsonCredentials 和ProjectId 来规避这两个问题：
var builder = new FirestoreDbBuilder();
builder.JsonCredentials = "{\"type\": \"service_account\", \"project_id\": \"\", \"private_key_id\": \"\", \"private_key\": \"\", \"client_email\": \"\", \"client_id\": \"\", \"auth_uri\": \"https://accounts.google.com/o/oauth2/auth\", \"token_uri\": \"https://oauth2.googleapis.com/token\", \"auth_provider_x509_cert_url\": \"https://www.googleapis.com/oauth2/v1/certs\", \"client_x509_cert_url\": \"\" }";
builder.ProjectId = "";
FirestoreDb db = builder.Build();
这将导致下一个问题，使用的 GRPC 库不支持 Blazor/.NET WASM 导致此堆栈跟踪：
crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: Unsupported platform.
System.InvalidOperationException: Unsupported platform.
at Grpc.Core.Internal.NativeExtension.GetNativeLibraryFilename () [0x0003f] in T:\src\github\grpc\src\csharp\Grpc.Core\Internal\NativeExtension.cs:231
at Grpc.Core.Internal.NativeExtension.LoadUnmanagedLibrary () [0x0000a] in T:\src\github\grpc\src\csharp\Grpc.Core\Internal\NativeExtension.cs:93
at Grpc.Core.Internal.NativeExtension.LoadNativeMethods () [0x0001a] in T:\src\github\grpc\src\csharp\Grpc.Core\Internal\NativeExtension.cs:120
at Grpc.Core.Internal.NativeExtension..ctor () [0x00006] in T:\src\github\grpc\src\csharp\Grpc.Core\Internal\NativeExtension.cs:40
at Grpc.Core.Internal.NativeExtension.Get () [0x00022] in T:\src\github\grpc\src\csharp\Grpc.Core\Internal\NativeExtension.cs:65
at Grpc.Core.Internal.NativeMethods.Get () [0x00000] in T:\src\github\grpc\src\csharp\Grpc.Core\Internal\NativeMethods.cs:49
at Grpc.Core.GrpcEnvironment.GrpcNativeInit () [0x00016] in T:\src\github\grpc\src\csharp\Grpc.Core\GrpcEnvironment.cs:373
at Grpc.Core.GrpcEnvironment..ctor () [0x0001e] in T:\src\github\grpc\src\csharp\Grpc.Core\GrpcEnvironment.cs:302
at Grpc.Core.GrpcEnvironment.AddRef () [0x00028] in T:\src\github\grpc\src\csharp\Grpc.Core\GrpcEnvironment.cs:78
at Grpc.Core.Channel..ctor (System.String target, Grpc.Core.ChannelCredentials credentials, System.Collections.Generic.IEnumerable`1[T] options) [0x00041] in T:\src\github\grpc\src\csharp\Grpc.Core\Channel.cs:70
at Google.Api.Gax.Grpc.GrpcCore.GrpcCoreAdapter.CreateChannelImpl (System.String endpoint, Grpc.Core.ChannelCredentials credentials, Google.Api.Gax.Grpc.GrpcChannelOptions options) [0x00000] in T:\src\github\gax-dotnet\releasebuild\Google.Api.Gax.Grpc.GrpcCore\GrpcCoreAdapter.cs:34
at Google.Api.Gax.Grpc.GrpcAdapter.CreateChannel (System.String endpoint, Grpc.Core.ChannelCredentials credentials, Google.Api.Gax.Grpc.GrpcChannelOptions options) [0x00024] in T:\src\github\gax-dotnet\releasebuild\Google.Api.Gax.Grpc\GrpcAdapter.cs:29
at Google.Api.Gax.Grpc.ClientBuilderBase`1[TClient].CreateChannel (System.String endpoint, Grpc.Core.ChannelCredentials credentials) [0x00000] in T:\src\github\gax-dotnet\releasebuild\Google.Api.Gax.Grpc\ClientBuilderBase.cs:423
at Google.Api.Gax.Grpc.ClientBuilderBase`1[TClient].CreateCallInvokerAsync (System.Threading.CancellationToken cancellationToken) [0x00145] in T:\src\github\gax-dotnet\releasebuild\Google.Api.Gax.Grpc\ClientBuilderBase.cs:313
at Google.Cloud.Firestore.V1.FirestoreClientBuilder.BuildAsyncImpl (System.Threading.CancellationToken cancellationToken) [0x00033] in /_/apis/Google.Cloud.Firestore.V1/Google.Cloud.Firestore.V1/FirestoreClient.g.cs:285
at Google.Cloud.Firestore.FirestoreDbBuilder.BuildAsync (System.Threading.CancellationToken cancellationToken) [0x0015a] in /_/apis/Google.Cloud.Firestore/Google.Cloud.Firestore/FirestoreDbBuilder.cs:119
at BlazorFirestore.Pages.FetchData.OnInitializedAsync () [0x00061] in C:\Users\niels\source\repos\BlazorFirestore\Pages\FetchData.razor:12
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync () <0x2ff3be8 + 0x0013a> in <filename unknown>:0
这可以通过使用Grpc.Net.Client.Web 解决，这是一个适用于 Blazor 的 .NET 的 Grpc 实现。
创建以下类（灵感来自 Google's Source）：
using System;
using Grpc.Core;
using Google.Api.Gax.Grpc;
using Grpc.Net.Client;
using System.Net.Http;
using Grpc.Net.Client.Web;
// you'll need these packages
// Google.Apis.Auth, Google.Cloud.Firestore, Grpc.Net.Client, Grpc.Net.Client.Web
namespace BlazorFirestore
{
// most of the code was borrowed from https://github.com/googleapis/gax-dotnet/blob/master/Google.Api.Gax.Grpc.GrpcNetClient/GrpcNetClientAdapter.cs
public sealed class GrpcWebAdapter : GrpcAdapter
{
// this HttpClient using the GrpcWebHandler and mode is crucial to get Grpc to work for Firestore
private static HttpClient httpClient = new HttpClient(new GrpcWebHandler(GrpcWebMode.GrpcWeb, new HttpClientHandler()));
// Note: this is "Default" rather than "Instance" as we expect to have other factory methods later, e.g. accepting
// an HTTP client factory.
/// <summary>
/// Returns the default instance of this class.
/// </summary>
public static GrpcWebAdapter Default { get; } = new GrpcWebAdapter();
private GrpcWebAdapter()
{
}
/// <inheritdoc />
protected override ChannelBase CreateChannelImpl(string endpoint, ChannelCredentials credentials, Google.Api.Gax.Grpc.GrpcChannelOptions options)
{
var grpcNetClientOptions = ConvertOptions(credentials, options);
var address = ConvertEndpoint(endpoint);
return GrpcChannel.ForAddress(address, grpcNetClientOptions);
}
// Internal for testing
internal static global::Grpc.Net.Client.GrpcChannelOptions ConvertOptions(ChannelCredentials credentials, Google.Api.Gax.Grpc.GrpcChannelOptions options)
{
// If service config resolution is explicitly enabled, throw - we can't support that,
// and users may be depending on it.
if (options.EnableServiceConfigResolution == true)
{
throw new ArgumentException($"{nameof(options.EnableServiceConfigResolution)} is not currently supported in {nameof(GrpcWebAdapter)}");
}
if (options.CustomOptions.Count > 0)
{
throw new ArgumentException($"Custom options are not currently supported in {nameof(GrpcWebAdapter)}");
}
// Options we ignore:
// - PrimaryUserAgent
// - KeepAliveTime
return new global::Grpc.Net.Client.GrpcChannelOptions
{
Credentials = credentials,
MaxReceiveMessageSize = options.MaxReceiveMessageSize,
MaxSendMessageSize = options.MaxSendMessageSize,
// pass the GrpcWeb version of the httpclient
HttpClient = httpClient
};
}
// Internal for testing
internal static string ConvertEndpoint(string endpoint) =>
// Note that we assume HTTPS for any bare address; this feels like a reasonable assumption for now.
endpoint.StartsWith("http:", StringComparison.Ordinal) || endpoint.StartsWith("https:", StringComparison.Ordinal)
? endpoint : $"https://{endpoint}";
}
}
现在将GrpcWebAdapter.Default 设置为FirestoreDbBuilder.GrpcAdapter：
var builder = new FirestoreDbBuilder();
builder.JsonCredentials = "{\"type\": \"service_account\", \"project_id\": \"\", \"private_key_id\": \"\", \"private_key\": \"\", \"client_email\": \"\", \"client_id\": \"\", \"auth_uri\": \"https://accounts.google.com/o/oauth2/auth\", \"token_uri\": \"https://oauth2.googleapis.com/token\", \"auth_provider_x509_cert_url\": \"https://www.googleapis.com/oauth2/v1/certs\", \"client_x509_cert_url\": \"\" }";
builder.ProjectId = "";
builder.GrpcAdapter = GrpcWebAdapter.Default;
FirestoreDb db = builder.Build();
DocumentReference docRef = db.Collection("users").Document("alovelace");
Dictionary<string, object> user = new Dictionary<string, object>
{
{ "First", "Ada" },
{ "Last", "Lovelace" },
{ "Born", 1815 }
};
await docRef.SetAsync(user);
我们离我们更近了一步，但现在我们遇到了 CORS 安全问题，因为这种与 Firestore 通信的方式并非设计为从浏览器运行，并且无法结合此 SDK 配置 CORS。
这些是由此产生的错误：
Access to fetch at 'https://firestore.googleapis.com/google.firestore.v1.Firestore/Commit' from origin 'https://localhost:5001' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
dotnet.3.2.0.js:1 POST https://firestore.googleapis.com/google.firestore.v1.Firestore/Commit net::ERR_FAILED
blazor.webassembly.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: Status(StatusCode="Internal", Detail="Error starting gRPC call. JSException: TypeError: Failed to fetch", DebugException="WebAssembly.JSException: TypeError: Failed to fetch
at System.Net.Http.WebAssemblyHttpHandler.doFetch (System.Threading.Tasks.TaskCompletionSource`1[TResult] tcs, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x3c61b60 + 0x00a30> in <filename unknown>:0
at System.Net.Http.WebAssemblyHttpHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x3c24040 + 0x00174> in <filename unknown>:0
at Grpc.Net.Client.Web.GrpcWebHandler.SendAsyncCore (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x00092] in /_/src/Grpc.Net.Client.Web/GrpcWebHandler.cs:137
at System.Net.Http.HttpClient.FinishSendAsyncUnbuffered (System.Threading.Tasks.Task`1[TResult] sendTask, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationTokenSource cts, System.Boolean disposeCts) <0x3d9ae50 + 0x00134> in <filename unknown>:0
at Grpc.Net.Client.Internal.GrpcCall`2[TRequest,TResponse].RunCall (System.Net.Http.HttpRequestMessage request, System.Nullable`1[T] timeout) [0x0020c] in /_/src/Grpc.Net.Client/Internal/GrpcCall.cs:477 ")
Grpc.Core.RpcException: Status(StatusCode="Internal", Detail="Error starting gRPC call. JSException: TypeError: Failed to fetch", DebugException="WebAssembly.JSException: TypeError: Failed to fetch
at System.Net.Http.WebAssemblyHttpHandler.doFetch (System.Threading.Tasks.TaskCompletionSource`1[TResult] tcs, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x3c61b60 + 0x00a30> in <filename unknown>:0
at System.Net.Http.WebAssemblyHttpHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x3c24040 + 0x00174> in <filename unknown>:0
at Grpc.Net.Client.Web.GrpcWebHandler.SendAsyncCore (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x00092] in /_/src/Grpc.Net.Client.Web/GrpcWebHandler.cs:137
at System.Net.Http.HttpClient.FinishSendAsyncUnbuffered (System.Threading.Tasks.Task`1[TResult] sendTask, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationTokenSource cts, System.Boolean disposeCts) <0x3d9ae50 + 0x00134> in <filename unknown>:0
at Grpc.Net.Client.Internal.GrpcCall`2[TRequest,TResponse].RunCall (System.Net.Http.HttpRequestMessage request, System.Nullable`1[T] timeout) [0x0020c] in /_/src/Grpc.Net.Client/Internal/GrpcCall.cs:477 ")
at Google.Api.Gax.Grpc.ApiCallRetryExtensions+<>c__DisplayClass0_0`2[TRequest,TResponse].<WithRetry>b__0 (TRequest request, Google.Api.Gax.Grpc.CallSettings callSettings) [0x00051] in T:\src\github\gax-dotnet\releasebuild\Google.Api.Gax.Grpc\ApiCallRetryExtensions.cs:27
at Google.Cloud.Firestore.WriteBatch.CommitAsync (Google.Protobuf.ByteString transactionId, System.Threading.CancellationToken cancellationToken) [0x000b5] in /_/apis/Google.Cloud.Firestore/Google.Cloud.Firestore/WriteBatch.cs:231
at Google.Cloud.Firestore.DocumentReference.SetAsync (System.Object documentData, Google.Cloud.Firestore.SetOptions options, System.Threading.CancellationToken cancellationToken) [0x0004b] in /_/apis/Google.Cloud.Firestore/Google.Cloud.Firestore/DocumentReference.cs:181
at BlazorFirestore.Pages.FetchData.OnInitializedAsync () [0x00166] in C:\Users\niels\source\repos\BlazorFirestore\Pages\FetchData.razor:21
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync () <0x2ff3be8 + 0x0013a> in <filename unknown>:0
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask (System.Threading.Tasks.Task taskToHandle) <0x3905a50 + 0x000b6> in <filename unknown>:0
当您在浏览器中使用 .\chrome.exe --disable-web-security 明确禁用 CORS 时，结果将是成功的身份验证，但实际 API 将返回 404。
我不清楚为什么它返回 404。我可以用 Fiddler 嗅探Grpc.Net.Client.Web 版本，但默认实现不会被 Fiddler 拦截。
看起来网络版本使用了不支持的不同协议/传输或其他东西。希望有人能解决下一个问题。
结论：用于 .NET 的 Firestore 库不应该在浏览器沙箱中使用，也不支持这种方式。