在上一節當中已經介紹了RavenDb的文件設計模式，這一節我們要具體講一講如何使用api去訪問RavenDb

1.連線RavenDb



var documentStore = new DocumentStore { Url = "http://myravendb.mydomain.com/" };

documentStore.Initialize();



var documentStore = new DocumentStore

{

ConnectionStringName = "MyRavenConStr"

};

在app.config中配置如下：

<connectionStrings>

<add name="Local" connectionString="DataDir = ~Data"/>

<add name="Server" connectionString="Url = http://localhost:8080"/>

<add name="Secure" connectionString="Url = http://localhost:8080;user=beam;password=up;ResourceManagerId=d5723e19-92ad-4531-adad-8611e6e05c8a"/>

</connectionStrings>



引數：

DataDir - embedded mode的引數, 只能例項化一個EmbeddableDocumentStore,

Url -  server mode的引數

User / Password - server mode的引數

Enlist - whatever RavenDB should enlist in distributed transactions. 不適合Silverlight

ResourceManagerId - 可選的, server mode的引數, the Resource Manager Id that will be used by the Distributed Transaction Coordinator (DTC) service to identify Raven. A custom resource manager id will need to be configured for each Raven server instance when Raven is hosted more than once per machine.不適合Silverlight

Database - server mode的引數,不是用內建的資料庫

Url的方式：

Url = http://ravendb.mydomain.com
connect to a remote RavenDB instance at ravendb.mydomain.com, to the default database
Url = http://ravendb.mydomain.com;Database=Northwind
connect to a remote RavenDB instance at ravendb.mydomain.com, to the Northwind database there
Url = http://ravendb.mydomain.com;User=user;Password=secret
connect to a remote RavenDB instance at ravendb.mydomain.com, with the specified credentials
DataDir = ~App_DataRavenDB;Enlist=False 
use embedded mode with the database located in the App_DataRavenDB folder, without DTC support.
2.Session使用案例
//寫入
string companyId;

using (var session = documentStore.OpenSession())

{

    var entity = new Company { Name = "Company" };

    session.Store(entity);

    session.SaveChanges();

    companyId = entity.Id;

}

//讀取

using (var session = documentStore.OpenSession())

{

    var entity = session.Load<Company>(companyId);

    Console.WriteLine(entity.Name);

}

//刪除,一旦刪除無法恢復

using (var session = documentStore.OpenSession())

{

session.Delete(existingBlogPost);

session.SaveChanges();

}

下面兩種方式也可以刪除 session.Advanced.Defer(new DeleteCommandData { Key = "posts/1234" });

session.Advanced.DocumentStore.DatabaseCommands.Delete("posts/1234", null);



3.查詢

//PageSize

如果沒有設定PageSize，客戶端呼叫是一次128條記錄，服務端呼叫是一次1024條記錄，遠端呼叫是一次30條記錄，可以配置。

RavenDb為了加快查詢資料的速度，它在後臺使用的是lucene的索引方式，通過linq來生成HTTP RESTful API。

//查詢,用linq的方式查詢很方便

var results = from blog in session.Query<BlogPost>()

              where blog.Category == "RavenDB"

              select blog;

var results = session.Query<BlogPost>()

    .Where(x => x.Comments.Length >= 10)

    .ToList();



//分頁查詢

var results = session.Query<BlogPost>()

    .Skip(20) // skip 2 pages worth of posts

    .Take(10) // Take posts in the page size

    .ToArray(); // execute the query



//分頁的時候，我們一次取10條，但是我們也要知道總共有多少條資料，我們需要通過TotalResults來獲得

RavenQueryStatistics stats;

var results = session.Query<BlogPost>()

    .Statistics(out stats)

    .Where(x => x.Category == "RavenDB")

    .Take(10)

    .ToArray();

var totalResults = stats.TotalResults;



//跳過指定的臨時的資料集，每次查詢都記錄下上一次查詢記錄的跳過的查詢記錄，該值儲存在SkippedResults

RavenQueryStatistics stats;

// get the first page

var results = session.Query<BlogPost>()

    .Statistics(out stats)

    .Skip(0 * 10) // retrieve results for the first page

    .Take(10) // page size is 10

    .Where(x => x.Category == "RavenDB")

    .Distinct()

    .ToArray();

var totalResults = stats.TotalResults;

var skippedResults = stats.SkippedResults;

 

// get the second page

results = session.Query<BlogPost>()

    .Statistics(out stats)

    .Skip((1 * 10) + skippedResults) // retrieve results for the second page, taking into account skipped results

    .Take(10) // page size is 10

    .Where(x => x.Category == "RavenDB")

    .Distinct()

    .ToArray();

//查詢出來的資料不一定是最新的,如果stats.IsStale不為true的話，它就報錯的啦

if (stats.IsStale)

{

    // Results are known to be stale

}



//設定獲取時間，更新時間截止到某個時刻

RavenQueryStatistics stats;

var results = session.Query<Product>()

    .Statistics(out stats)

    .Where(x => x.Price > 10)

    .Customize(x => x.WaitForNonStaleResultsAsOf(new DateTime(2011, 5, 1, 10, 0, 0, 0)))

    .ToArray();



//設定查詢返回最後一次更新 documentStore.Conventions.DefaultQueryingConsistency = ConsistencyOptions.QueryYourWrites;