Question

我一直在尝试通过visual studio 2015中的Web服务连接到Microsoft SQL Server。但是，我在尝试从数据库中检索数据时遇到了困难。

在我的网络配置文件中，我有以下代码：

<add name="SecondlyReadingsContext" connectionString="Data Source=myserver;Initial Catalog=SecondlyReadingsContext;user=sa;password=adminadmin2" providerName="System.Data.SqlClient" />

我假设（可能是错误的）上面的代码与服务器和数据库本身建立了连接。我从以下链接引用了上面的代码： Connecting to SQL server from Restful C# service

在我的Model类中，我有以下代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;

namespace HelloWorld.Models.APiModels
{
    public class SecondlyReading
    {

        [Key]
        public int Id { get; set; }
        [Required]
        public int ChannelID { get; set; }
        [Required]
        public string TimeStamp { get; set; }
        [Required]
        public float RMSVoltage { get; set; }
        [Required]
        public float Frequency { get; set; }
        [Required]
        public float RMSCurrent { get; set; }
        [Required]
        public float RealPower { get; set; }
        [Required]
        public float ReactivePower { get; set; }
        [Required]
        public float ApparentPower { get; set; }
        [Required]
        public float PowerFactor { get; set; }
        [Required]
        public string DeviceId { get; set; }

        //[ForeignKey("DeviceId")]
        //public virtual Device Device { get; set; }

    }
}

在我的控制器中，我有这个：

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.Description;
using HelloWorld.Models;
using HelloWorld.Models.APiModels;

namespace HelloWorld.Controllers
{
    public class SecondlyReadingsController : ApiController
    {
        private SecondlyReadingsContext db = new SecondlyReadingsContext();

        // GET: api/SecondlyReadings
        public IQueryable<SecondlyReading> GetSecondlyReadings()
        {
            return db.SecondlyReadings;
        }

        // GET: api/SecondlyReadings/5
        [ResponseType(typeof(SecondlyReading))]
        public IHttpActionResult GetSecondlyReading(int id)
        {
            SecondlyReading secondlyReading = db.SecondlyReadings.Find(id);
            if (secondlyReading == null)
            {
                return NotFound();
            }

            return Ok(secondlyReading);
        }

        // PUT: api/SecondlyReadings/5
        [ResponseType(typeof(void))]
        public IHttpActionResult PutSecondlyReading(int id, SecondlyReading secondlyReading)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != secondlyReading.Id)
            {
                return BadRequest();
            }

            db.Entry(secondlyReading).State = EntityState.Modified;

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!SecondlyReadingExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }

        // POST: api/SecondlyReadings
        [ResponseType(typeof(SecondlyReading))]
        public IHttpActionResult PostSecondlyReading(SecondlyReading secondlyReading)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            db.SecondlyReadings.Add(secondlyReading);
            db.SaveChanges();

            return CreatedAtRoute("DefaultApi", new { id = secondlyReading.Id }, secondlyReading);
        }

        // DELETE: api/SecondlyReadings/5
        [ResponseType(typeof(SecondlyReading))]
        public IHttpActionResult DeleteSecondlyReading(int id)
        {
            SecondlyReading secondlyReading = db.SecondlyReadings.Find(id);
            if (secondlyReading == null)
            {
                return NotFound();
            }

            db.SecondlyReadings.Remove(secondlyReading);
            db.SaveChanges();

            return Ok(secondlyReading);
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                db.Dispose();
            }
            base.Dispose(disposing);
        }

        private bool SecondlyReadingExists(int id)
        {
            return db.SecondlyReadings.Count(e => e.Id == id) > 0;
        }
    }
}

我也被告知我应该在以下的SecondReadingContext.cs文件中进行某种数据库连接，但我不确定如何去做：

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;

namespace HelloWorld.Models
{
    public class SecondlyReadingsContext : DbContext
    {
        // You can add custom code to this file. Changes will not be overwritten.
        // 
        // If you want Entity Framework to drop and regenerate your database
        // automatically whenever you change your model schema, please use data migrations.
        // For more information refer to the documentation:
        // http://msdn.microsoft.com/en-us/data/jj591621.aspx

        public SecondlyReadingsContext() : base("name=SecondlyReadingsContext")
        {   

        }

        public System.Data.Entity.DbSet<HelloWorld.Models.APiModels.SecondlyReading> SecondlyReadings { get; set; }
    }
}

当我通过IIS管理器运行我的服务器并将api / SecondReadings添加到url时，我应该以json格式返回数据，但是，我没有检索任何数据并且它返回一个空白页面（在记事本中），因为我在Internet Explorer中运行它。有人会告诉我在我的代码中做错了什么，或者我错过了什么。我已经在这方面工作了一段时间，非常感谢任何帮助。

作为参考，这是我添加到我试图检索的Microsoft SQL服务器中的虚拟数据：

添加绑定后的上下文文件：

编辑web.config文件后出现

错误：

编辑web.config文件后更新结果

Answer 1

在此处设置表格绑定以获取数据

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{

}
public virtual DbSet<SecondlyReading> SecondlyReadings { get; set; }

请记住在SQL Server End上重命名您的表名。到SecondReading

从ASP.NET Web服务

1 个答案: