什么是Google.Cloud.Datastore.V1中的密钥 [英] What is Key in Google.Cloud.Datastore.V1

问题描述

我是这个nuget包的新手，并与 Key 类混淆.

I'm new to this nuget package and confused with the Key class.

这是我的代码基于 Google. Cloud.Datastore.V1 文档:

Here is my code base on Google.Cloud.Datastore.V1 document:

public long InsertMessage<T>(T iEntity) where T : IEntity<T>
{
    var keyFactory = _db.CreateKeyFactory(Kind);
    var entity = iEntity.ToEntity();
    entity.Key = keyFactory.CreateIncompleteKey();

    using (var transaction = _db.BeginTransaction())
    {
        transaction.Insert(entity);
        var commitResponse = transaction.Commit();
        var insertedKey = commitResponse.MutationResults[0].Key;
        Logger.Info($"Inserted key: {insertedKey}");
        return insertedKey.Path[0].Id;
    }
}

我要做的就是创建一个实体并创建一个不完整的密钥，发送给服务器，然后从服务器取回填充的密钥.

All I do is to create an entity and create an incomplete key, send to the server, then get the populated key back from server.

我认为密钥被用作实体的唯一身份.

如果有误会，请纠正我.

If there's misunderstanding please correct me.

我可以通过查询获取实体，如下所示:

I can get entities by Query as below:

var query = new Query(Kind)
{
    Filter = Filter.Equal("key", key),
    Order = { { "created", PropertyOrder.Types.Direction.Ascending } }
};
foreach (var entity in _db.RunQueryLazily(query))
{
    list.Add(entity);
}

但是我不知道如何使用插入时通过Filter.Equal("key", key)获取唯一实体的键.

But I don't know how to use the key I got when inserted to get the unique entity by Filter.Equal("key", key).

该示例显示键的结构为:

{
    "partitionId":
    {
        "projectId": "projectId",
        "namespaceId": "namespaceId"
    },
    "path": [
    {
        "kind": "kind",
        "id": "id"
    }]
}

在这里，我总结一下我的问题:

1. 密钥类的用途是什么?
2. Key的路径是什么，为什么是数组?
3. id是实体的唯一密钥吗?
4. 如何通过Key和Id来Query?

1. What is Key class for?
2. What is Key's path and why it's array?
3. Is id the unique key to the entity?
4. How to Query by Key and Id?

感谢您的阅读，请不要介意我的英语不好.

Thanks for reading and please don't mind my poor English.

推荐答案

键是文档的唯一标识符. 文档表示最好:

A key is a unique identifier for a document. The documentation says it best:

Cloud Datastore中的每个实体都有一个唯一标识它的 key .密钥包含以下组件:

Each entity in Cloud Datastore has a key that uniquely identifies it. The key consists of the following components:

• 实体的命名空间，允许多租户
• 实体的种类，出于Cloud Datastore查询的目的对其进行了分类
• 单个实体的标识符，可以是
  • 键名字符串
  • 整数数字ID
  • The namespace of the entity, which allows for multitenancy
  • The kind of the entity, which categorizes it for the purpose of Cloud Datastore queries
  • An identifier for the individual entity, which can be either
    • a key name string
    • an integer numeric ID

    祖先路径"部分原因是Path属性中存在数组的原因-完全限定的键是名称空间，后跟一系列

    The "ancestor path" part is the reason there's an array in the Path property - a fully qualified key is a namespace followed by a sequence of path elements, each of which consists of a kind and "integer ID" or "string name" part.

    例如，您可能有一个图书馆应用程序.那有书架和书本.忽略名称空间部分，特定的书可能具有一个包含以下路径元素的ID:

    So for example, you might have a library application. That has shelves and books. Ignoring the namespace part, a particular book might have an ID with path elements of:

    • 种类=货架； Id = 1(数字ID)
    • Kind = Book;名称= xyz(字符串名称)

    另一种思考方式就像是集合和文档名称的交替序列，例如"/shelves/1/books/xyz".这就是 Firestore 表示其文档ID的方式.

    Another way of thinking of this is like an alternating sequence of collection and document names, e.g. "/shelves/1/books/xyz". That's how Firestore represents its document IDs.

    任何一个路径元素都不必是唯一的，但是完整的路径是唯一的.没有真正的概念通过键和ID"进行查询. -您可以查找完整的键(例如DatastoreDb.Lookup)，也可以包含父键作为祖先路径查询.

    Any one path element doesn't have to be unique, but the complete path is unique. There's no real concept of querying by "key and ID" - you can look up a complete key (e.g. DatastoreDb.Lookup) or include a parent key as an ancestor path query.

    这篇关于什么是Google.Cloud.Datastore.V1中的密钥的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！