WCF Data Services客户端访问

上一篇http://www.cnblogs.com/2018/archive/2010/10/17/1853384.html 

讲述了查询的相关语法和例子，如果在程序中如何使用这些发布的服务呢？下面对在代码中访问这些服务的方法进行一下汇总

客户端访问

查询

这些查询中可以结合上文的查询语法等使用 Ø 浏览器地址：输入地址，GET请求直接进行 Ø JavaScipt库：如ExtJS、DOJO、MS AJAX等支持JSON处理的JS库 Ø Service Reference引用 常用的形式，IDE直接添加引用，使用代理对象和上下文处理 //Generic泛型                     {                            DataServiceContext ctx = new DataServiceContext(u);                            var q = ctx.Execute<Order>(new Uri("/Orders(10402)", UriKind.Relative));                            foreach (var t in q)                            {                                   Console.WriteLine(t.OrderDate);                            }                     }               //Client Proxy代理                     {                            NorthwindEntities ctx = new NorthwindEntities(u);                            var q = from c in ctx.Suppliers select c;                            foreach (var t in q)                            {                                   Console.WriteLine(t.City);                            } Ø HTTP协议支持处理        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url + "/Orders(10402)");                            req.Method = "GET";                            req.Accept = "application/json";                            using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())                            {                                   using (StreamReader sr = new StreamReader(resp.GetResponseStream()))                                   {                                          Console.WriteLine(sr.ReadToEnd());                                   }                            }                            req = (HttpWebRequest)WebRequest.Create(url + "/Orders(10402)");                            req.Method = "GET";                            req.Accept = "application/atom+xml";                            using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())                            {                                   using (StreamReader sr = new StreamReader(resp.GetResponseStream()))                                   {                                          XmlDocument xml = new XmlDocument();                                          xml.Load(sr);                                          Console.WriteLine(xml.InnerXml);                                   }                            }

增删改

Ø HTTP形式 参考MSDN的规定传递参数和请求形式即可，处理有些麻烦 Ø Service Reference引用 比较常用的形式，具体参考“修改数据”一节 需要处理并发冲突： DataServiceRequestException · Entity Framework provider - In the data model, the ConcurrencyMode attribute of a property that is part of the concurrency token for an entity type is set to Fixed. · Reflection provider - The ETagAttribute is applied to the data class that is an entity type. This attribute declares the concurrency token based on the supplied property names.

修改数据

Insert	HTTP POST Content-Type：需正确设置
Update	HTTP Put/Merger
Delete	HTTP Delete

例子

需要修改数据对象，注意服务端需要设置正确的属性，如：

            config.SetEntitySetAccessRule("*", EntitySetRights.All);

            config.SetServiceOperationAccessRule("*", ServiceOperationRights.All);

            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;

客户端通过代理访问：

//Client Proxy

{

NorthwindEntities ctx = new NorthwindEntities(u);

var q = from c in ctx.Suppliers select c;

foreach (var t in q)

{

Console.WriteLine(t.City);

}

///添加

var cust = new Customer()

{

CustomerID = "Test1",

Address = "Beijing",

City = "Peking",

CompanyName = "demo",

ContactName = "test",

ContactTitle = "mr.",

Country = "China",

Fax = "123",

Phone = "111",

PostalCode = "456",

Region = "HD"

};

ctx.AddToCustomers(cust);

ctx.SaveChanges();

///更新

var upCust = (from c in ctx.Customers where c.CustomerID == cust.CustomerID select c).FirstOrDefault();

upCust.ContactName += "-UPD";

ctx.UpdateObject(upCust);

ctx.SaveChanges();

///删除

upCust = (from c in ctx.Customers where c.CustomerID == cust.CustomerID select c).FirstOrDefault();

ctx.DeleteObject(upCust);

ctx.SaveChanges();

可见,在客户端可以使用LINQ语法进行查询

除了客户端，服务端也有很强的支持，下文再说。