ASP .NET+Angular前后端分离实现简单投票系统（上）

该投票系统实现的功能较为简单，适合初学者借鉴。

数据库表只有三张：用户表、投票信息表和投票选项表，采用的是SQLServer数据库，后端采用ASP .NET框架（C#），前端采用Angular，UI组件采用的是NG-ZORRO。功能较简单，有用户登录与注册、查看投票列表，进行投票，发起投票，查看投票结果等功能。

第一步：在Visual Studio 2019创建一个新的项目

第二步：创建数据实体类的文件夹Models
User.cs

using System.ComponentModel.DataAnnotations.Schema;

namespace Vote_Api.Models
{

    [Table("UserInfo")]
    public class User
    {
        public string UserId { get; set; }

        public string Passwd { get; set; }

        public string Tel { get; set; }

        public int Age { get; set; }
    
        public string Sex { get; set; }
    
    }
}

VoteInfo.cs

using System;
using System.ComponentModel.DataAnnotations.Schema;

namespace Vote_Api.Models
{

    [Table("VoteInfo")]
    public class VoteInfo
    {
        public int ID { get; set; }

        public string Vote_Title { get; set; }

        public int? Vote_Sum { get; set; }

        public DateTime Start_Time { get; set; }

        public DateTime End_Time { get; set; }

        public bool Vote_Type { get; set; }

        public string UserID { get; set; }
    }
}

VoteOption.cs

using System.ComponentModel.DataAnnotations.Schema;

namespace Vote_Api.Models
{

    [Table("VoteOption")]
    public class VoteOption
    {
        public int ID { get; set; }

        public string Vote_Item { get; set; }

        public int Vote_Num { get; set; }

        public int Vote_ID { get; set; }
    }
}

第三步：在appsettings.json添加配置数据库连接字符串

"ConnectionStrings": {
    "sqlserverConn": "Server=地址;Database=数据库名;user id=用户名;password=密码;"
  }

第四步：在Models中创建一个类继承DbContext

using Microsoft.EntityFrameworkCore;

namespace Vote_Api.Models
{
    public class VoteContext :DbContext
    {
        public VoteContext(DbContextOptions options) : base(options) { }
             
        public DbSet User_Info { get; set; }

        public DbSet Vote_Info { get; set; }

        public DbSet Vote_Option { get; set; }
    }
}

还要在Startup.cs的ConfigureService方法中添加注入

 public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddDbContext(options =>
            options.UseSqlServer(Configuration.GetConnectionString("sqlserverConn"))); //"sqlserverConn"是之前在appsettings.json中配置的连接字符串
         }

第五步：编写业务逻辑
IVoteInfoService.cs

using System;
using Vote_Api.Models;

namespace Vote_Api.Service.IService
{
    public  interface IVoteInfoService
    {
        int  AddVote(VoteInfo vote);  //发起投票

        bool AddVoteOption(VoteOption voteop);  //添加投票选项

        string getAllVotes();  //获取所有投票列表

        string getVoteById(int id);  //查看某个投票详情

        string getVoteOptionById(int id);   //获取某个投票选项

        bool doVote(int id);   //进行投票

        string getMyVotes(string user_id);   //获取某个用户发起的投票列表
    }
}

接口实现类VoteInfoService.cs

using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using Vote_Api.Models;
using Vote_Api.Service.IService;

namespace Vote_Api.Service.ServiceImpl
{
    public class VoteInfoService : IVoteInfoService
    {
        private readonly VoteContext _context;

        public VoteInfoService(VoteContext context)
        {
            _context = context;     //注入数据库上下文
        }

        public int AddVote(VoteInfo vote)
        {
            _context.Vote_Info.Add(vote);

            int res = _context.SaveChanges();

            if(res == 1)
            {
                return vote.ID;  //添加投票信息成功后返回id
            }
            else
            {
                return 0;
            }
        }

        public bool AddVoteOption(VoteOption voteop)
        {
            _context.Vote_Option.Add(voteop);

            int res = _context.SaveChanges();

            if(res == 1)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        public string getAllVotes()
        {
           
            List votes = _context.Vote_Info.ToList();

            _context.SaveChanges();

            return JsonConvert.SerializeObject(votes);  //序列化
        }

        public string getVoteById(int id)
        {
            VoteInfo vote = _context.Vote_Info.Find(id);

            _context.SaveChanges();

            return JsonConvert.SerializeObject(vote);
        }

        public string getVoteOptionById(int id)
        {
            string sql = "select * from VoteOption where Vote_ID = "+id;

            var voteOption = _context.Vote_Option.FromSqlRaw(sql);  //采用原生的Sql语句

            _context.SaveChanges();

            return JsonConvert.SerializeObject(voteOption);
        }

        public bool doVote(int id)
        {
            VoteOption vop = _context.Vote_Option.Find(id);
            vop.Vote_Num += 1; 
            VoteInfo v =_context.Vote_Info.Find(vop.Vote_ID);
            v.Vote_Sum += 1;
            int res = _context.SaveChanges();
            Console.WriteLine(res);

            if (res == 2 )
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        public string getMyVotes(string user_id)
        {
            string sql = "select * from VoteInfo where UserID = '" + user_id+"'";

            var myvote = _context.Vote_Info.FromSqlRaw(sql);

            _context.SaveChanges();

            return JsonConvert.SerializeObject(myvote);
        }
    }
}

第六步：同样需要在在Startup.cs中添加注入服务

 public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddDbContext(options =>
            options.UseSqlServer(Configuration.GetConnectionString("sqlserverConn")));

            services.AddTransient();//注入刚刚创建的接口和实现类
         }

第七步：创建Controller，编写接口

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Vote_Api.Models;
using Vote_Api.Service.IService;

namespace Vote_Api.Controllers
{
    [Route("api/vote")]
    [ApiController]
    public class VoteController : Controller
    {
        private readonly IVoteInfoService _service;
        public VoteController(IVoteInfoService service)
        {
            _service = service;
        }

        [HttpGet("getAllVotes")]
        public string getAllVotes()
        {
            return _service.getAllVotes();
        }

        [HttpGet("getVoteById")]
        public string getVoteById(int vote_id)
        {
            return _service.getVoteById(vote_id);
        }


        [HttpGet("getVoteOptionById")]
        public string getVoteOptionById(int vote_option_id)
        {
            return _service.getVoteOptionById(vote_option_id);
        }

        [HttpGet("doVote")]
        public bool doVote(int vote_option_id)
        {
            return _service.doVote(vote_option_id);
        }

        [HttpGet("getMyVotes")]
        public string getMyVotes(string user_id)
        {
            return _service.getMyVotes(user_id);
        }

        [HttpPost("AddVote")]
        public int AddVote(VoteInfo vote)
        {
            return _service.AddVote(vote);
        }

        [HttpPost("AddVoteOption")]
        public bool AddVoteOption(VoteOption voteop)
        {
            return _service.AddVoteOption(voteop);
        }
    }
}

第八步：postman测试api

到此投票模块的功能api已经简单完成，下一篇会讲登录模块的api实现。写得很简单，适合初学者。如有不足，评论区见。