如何使用servicestack.aws PocoDynamo批量获取项目？

Question

对于亚马逊原生.net库，batchget如下所示

var batch = context.CreateBatch<MyClass>();
batch.AddKey("hashkey1");
batch.AddKey("hashkey2");
batch.AddKey("hashkey3");
batch.Execute();
var result = batch.results;

现在我正在测试使用servicestack.aws，但是我不知道该怎么做。我尝试了以下两种方法，都失败了。

//1st try
var q1 = db.FromQueryIndex<MyClass>(x => x.room_id == "hashkey1" || x.room_id == "hashkey2"||x.room_id == "hashkey3");
var result = db.Query(q1);

//2nd try
var result = db.GetItems<MyClass>(new string[]{"hashkey1","hashkey2","hashkey3"});

在这两种情况下，它都会抛出一个异常，说明附加信息:在KeyConditionExpression: OR中使用的运算符无效

请帮帮我。谢谢!

Answer 1

使用GetItems的工作方式应该与此Live Example on Gistlyn的工作方式相同

public class MyClass
{
    public string Id { get; set; }
    public string Content { get; set; }
}

db.RegisterTable<MyClass>();

db.DeleteTable<MyClass>();  // Delete existing MyClass Table (if any)
db.InitSchema();         // Creates MyClass DynamoDB Table

var items = 5.Times(i => new MyClass { Id = $"hashkey{i}", Content = $"Content {i}" });
db.PutItems(items);

var dbItems = db.GetItems<MyClass>(new[]{ "hashkey1","hashkey2","hashkey3" });
"Saved Items: {0}".Print(dbItems.Dump());

如果您的项目同时具有散列和范围键，则需要使用GetItems<T>(IEnumerable<DynamoId> ids)应用编程接口，例如：

var dbItems = db.GetItems<MyClass>(new[]{
    new DynamoId("hashkey1","rangekey1"),
    new DynamoId("hashkey2","rangekey3"),
    new DynamoId("hashkey3","rangekey4"),
});

查询具有相同HashKey的所有项目

如果您想获取具有相同HashKey的所有项，则需要像使用此Live Gistlyn Example时一样执行create a DynamoDB Query

var items = 5.Times(i => new MyClass { 
    Id = $"hashkey{i%2}", RangeKey = $"rangekey{i}", Content = $"Content {i}" });
db.PutItems(items);

var rows = db.FromQuery<MyClass>(x => x.Id == "hashkey1").Exec().ToArray();
rows.PrintDump();