如何将对象从Xamarin表单保存到AWS DynamoDB

我正在创建一个移动应用程序，允许用户使用AWS Cognito通过facebook登录。处理类似以下内容的代码

public async Task FacebookCongitoLogin(FacebookProfile profile)
{

        config = new AmazonCognitoSyncConfig { RegionEndpoint = RegionEndpoint.USEast1 };
        creds = new CognitoAWSCredentials("ARN_ID_STUFF", RegionEndpoint.USEast1);
        creds.AddLogin("graph.facebook.com", MySettings.FBToken);

        syncManager = new CognitoSyncManager(creds, config);

        await creds.GetCredentialsAsync();

        Content = null;
        saveProfileInfo(profile);
 }

private void saveProfileInfo(FacebookProfile profile)
{
    Dataset profileData = syncManager.OpenOrCreateDataset("fb_profile");
                profileData.OnSyncSuccess += SyncSuccessCallback;
                profileData.OnSyncFailure += SyncFailureCallback;
    profileData.Put("fb_profile",JsonConvert.SerializeObject(profile));
                profileData.SynchronizeAsync();
}

在我让用户登录之后，我正试图将一个对象安全地保存到我新创建的DynamoDB表中，就像这样

using System;
using System.Threading.Tasks;
using Amazon;
using Amazon.CognitoIdentity;
using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.DataModel;

namespace TechPact
{
    public class CreateInviteAction
    {
        private CognitoAWSCredentials creds;
        public CreateInviteAction()
        {
            var token = TechPactSettings.FBToken;
            creds = new CognitoAWSCredentials("ARN_ID_KEY", RegionEndpoint.USEast1);
            creds.AddLogin("graph.facebook.com", token);
            creds.GetCachedCredentials();

        }

        public async Task execute(Invite invite)
        {
            var client = new AmazonDynamoDBClient(creds, RegionEndpoint.USEast1);
            var context = new DynamoDBContext(client);

            await context.SaveAsync(invite);

        }
    }
}

当上面的操作运行时，我得到一个AmazondynamodException

用户：arn:aws:sts:：12323424:assumedrole/inviteapp\u auth\u MOBILEHUB\u 123234245/CognitoIdentityCredentials未被授权在资源上执行：dynamodb:可描述：arn:aws:dynamodb:us-ease-1:1232314234:table/Invite

下面是我为用户池创建的自定义角色police

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "dynamodb:*"
            ],
            "Resource": [
                "arn:aws:dynamodb:us-east-1:12312312312:table/invite-mobilehub-234234234-Invite"
            ],
            "Condition": {
                "ForAllValues:StringEquals": {
                    "dynamodb:LeadingKeys": [
                        "${graph.facebook.com:id}"
                    ]
                }
            }
        }
    ]
}

---

您能否共享链接到此池的IAM角色？它们会在创建身份池时自动创建。通过该消息，您似乎需要将dynamodb:descripbetable添加到您的身份验证角色中。@JeffBailey在上面添加了我从Congnito角色生成器生成的角色。我确实为这篇文章更改了一些dynamodb arn的数字，但是其他的都是我在用户池角色policy中所做的，这个角色中的资源看起来很混乱。它应该是“arn:aws:dynamodb:：：table/，根据您的错误消息，这意味着它的表名是错误的。您是否认为它应该是类似于arn:aws:dynamodb:us-east-1:12312:table/invited的内容？是的，请试一试。作为对未来发现这个问题的人的补充，一位前Cognito团队成员写了一篇关于这个主题的优秀博客：