使用Sqlite数据库
创建项目
Asp.Net Core Web应用程序
Web应用程序 ASP.NET Core 2.2
NuGet管理，添加Sqlite数据库支持
Microsoft.EntityFrameworkCore.Sqlite
添加数据实体类
添加文件夹Models
在Models文件夹添加类 Test Context
using System.Collections.Generic;using Microsoft.EntityFrameworkCore;using System.ComponentModel.DataAnnotations; namespace WebApplication1.Models{ ???public class TestContext:DbContext ???{ ???????public TestContext(DbContextOptions<TestContext> options) ???????????: base(options) ???????{ ???????} ???????public DbSet<Person> People { get; set; } ???????public DbSet<Book> Books { get; set; } ???} ???public class Person ???{ ???????[Display( Name ="编号")] ???????public int PersonID { get; set; } ???????[Display(Name ="姓名")] ???????public string PersonName { get; set; } ???????[Display(Name ="书籍")] ???????public List<Book> Books { get; set; } ???} ???public class Book ???{ ???????[Display(Name ="编号")] ???????public int BookID { get; set; } ???????[Display(Name ="书名")] ???????public string BookName { get; set; } ???????[Display(Name ="人员编号")] ???????public int PersonID { get; set; } ???????[Display(Name ="人员")] ???????public Person Person { get; set; } ???}}更改Startup.cs文件
添加引用
using Microsoft.EntityFrameworkCore;using Microsoft.EntityFrameworkCore.Sqlite;
更新以下过程
public void ConfigureServices(IServiceCollection services){…… ???//实现注入 ???var dbpath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "test.db"); ???var connstr = $"Data Source={dbpath}"; ???services.AddDbContext<TestContext>(options => options.UseSqlite(connstr)); ???//自动创建数据库 ???var builder = new DbContextOptionsBuilder<TestContext>(); ???builder.UseSqlite(connstr); ???using (var db = new TestContext(builder.Options)) ???{ ???????db.Database.EnsureCreated(); ???}…… ??}添加Razor页面实现数据的增删改查
在Pages目录增加子目录 People和Books
在People目录右击鼠标，选择添加 新搭建基架的项目
选择使用实体框架生成Razor页面（CRUD）
在Books目录右击鼠标，选择添加 新搭建基架的项目
选择使用实体框架生成Razor页面（CRUD）
安装配置 Session
NuGet 添加引用
Microsoft.AspNetCore.Session
Session 是基于 IDistributedCache 构建的，所以必须引用一种 IDistributedCache 的实现，ASP.NET Core 提供了多种 IDistributedCache 的实现 （Redis、SQL Server、In-memory）
修改Startup.cs文件
public void ConfigureServices(IServiceCollection services){…… ???services.AddDistributedMemoryCache(); ???services.AddSession();……}public void Configure(IApplicationBuilder app, IHostingEnvironment env){…… ???app.UseSession(); ???……}使用Session
设置Session变量
public async Task OnGetAsync(){ ???Book = await _context.Books ???????.Include(b => b.Person).ToListAsync(); ????var s = "hello world @ " + DateTime.Now.ToString(); ???var b1 = System.Text.Encoding.UTF8.GetBytes(s); ???HttpContext.Session.Set("key1", b1);}读取Session变量
public async Task OnGetAsync(){ ???Person = await _context.People.ToListAsync(); ???byte[] data; ???var b = HttpContext.Session.TryGetValue("key1", out data); ???var s = System.Text.Encoding.UTF8.GetString(data); ???ViewData["key1"] = s;}通过字段属性实现数据校验
字段属性使用范例
[Display(Name ="分组编号")]public int GroupID { get; set; }[Display(Name ="分组名称")][Required(ErrorMessage = "分组名称不能为空")][RegularExpression(@"^[a-zA-Z]+[0-9]*", ErrorMessage = "只能使用英文字母和数字，并且第一个符号必须为英文字母。")][StringLength(20,MinimumLength =3,ErrorMessage ="最短长度3，最大长度20")]public string GroupName { get; set; }[Display(Name ="学生列表")]页面直接显示字段属性
列标题
@Html.DisplayNameFor(model => model.Administrator[0].UserName)
数据行
@Html.DisplayFor(modelItem => item.UserName)
使用正则表达式实现复杂校验
[RegularExpression(@"^[a-zA-Z]+[0-9]*", ErrorMessage = "只能使用英文字母和数字，并且第一个符号必须为英文字母。")]
自定义错误提示
ModelState的属性
这是一个类型为ModelStateDictionary的ModelState类型的字典集合。在进行数据验证的时候这个属性是比較实用的。在使用Html.ValidationMessage()的时候，就是从ViewData.ModelState中检測是否有指定的KEY。假设存在。就提示错误信息。
ModelState.AddModelError("LoginError", "登录失败");页面上增加以下代码：
<span class="text-danger">@Html.ValidationMessage("LoginError")</span>实现登录功能
添加Razor页面
页面代码如下：
@page@model CourseAssistant.Pages.Login.IndexModel@{ ???ViewData["Title"] = "登录";}<h1>登录</h1> <hr /><div class="row"> ???<div class="col-md-4"> ???????<form method="post"> ???????????<div asp-validation-summary="ModelOnly" class="text-danger"></div> ???????????<div class="form-group"> ???????????????<label asp-for="LoginEntry.UserName" class="control-label"></label> ???????????????<input asp-for="LoginEntry.UserName" class="form-control" /> ???????????????<span asp-validation-for="LoginEntry.UserName" class="text-danger"></span> ???????????</div> ???????????<div class="form-group"> ???????????????<label asp-for="LoginEntry.Password" class="control-label"></label> ???????????????<input asp-for="LoginEntry.Password" class="form-control" /> ???????????????<span asp-validation-for="LoginEntry.Password" class="text-danger"></span> ???????????</div> ???????????<div class="form-group"> ???????????????<input type="submit" value="登录" class="btn btn-primary" /> ???????????????<span class="text-danger">@Html.ValidationMessage("LoginError")</span> ???????????</div> ???????</form> ???</div></div> @section Scripts { ???@{await Html.RenderPartialAsync("_ValidationScriptsPartial");}}更新IndexModel代码
public class IndexModel : PageModel{ ???private readonly CourseAssistant.Models.CourseAssistantContext _context; ????public IndexModel(CourseAssistant.Models.CourseAssistantContext context) ???{ ???????_context = context; ???} ???[BindProperty] ???public LoginEntry LoginEntry { get; set; } ???public void OnGet() { } ???public async Task<IActionResult> OnPostAsync() ???{ ???????if (!ModelState.IsValid) ???????{ ???????????return Page(); ???????} ???????var admin = await _context.Administrators.FirstOrDefaultAsync(m => m.UserName == LoginEntry.UserName && m.Password == LoginEntry.Password); ???????if (admin != null) ???????{ ???????????this.SetCurrentUser(new LoginUser() { UserTyep = UserType.Administrator, Administrator = admin, Student = null }); ???????????return RedirectToPage("/Groups/Index"); ????????} ???????else ???????{ ????????????ModelState.AddModelError("LoginError", "登录失败"); ??????????return Page(); ???????} ???}} public class LoginEntry{ ???[Display(Name ="账号")] ???[Required(ErrorMessage = "用户名不能为空。")] ???[RegularExpression("^[a-zA-z]+[a-zA-z0-9]*",ErrorMessage ="只能使用英文和数字，并且第一个符号必须是英文")] ???[StringLength(20,MinimumLength =3,ErrorMessage="最大长度20，最小长度3")] ???public string UserName { get; set; } ???[Required(ErrorMessage = "密码不能为空。")] ???[DataType(DataType.Password)] ???[Display(Name = "密码")] ???[StringLength(20, MinimumLength = 3, ErrorMessage = "最大长度20，最小长度3")] ???public string Password { get; set; }}实现文件上传功能
添加Razor页面
页面代码如下：
@page@model CourseAssistant.Pages.FileUploads.IndexModel@{ ???ViewData["Title"] = "文件上传";}<h2>文件上传</h2><hr /><div class="row"> ???<div class="col-md-4"> ???????<form method="post" enctype="multipart/form-data"> ???????????<div class="form-group"> ???????????????<label asp-for="FileUpload.FileName" class="form-control"></label> ???????????????<input asp-for="FileUpload.FileName" type="text" class="form-control" /> ???????????????<span asp-validation-for="FileUpload.FileName" class="text-danger"></span> ???????????</div> ???????????<div class="form-group"> ???????????????<label asp-for="FileUpload.FileData" class="form-control"></label> ???????????????<input asp-for="FileUpload.FileData" type="file" class="form-control" style="height:auto;" /> ???????????????<span asp-validation-for="FileUpload.FileData" class="text-danger"></span> ???????????</div> ???????????<input type="submit" value="上传" class="btn btn-primary" /> ???????</form> ???</div></div>更新IndexModel代码
public class IndexModel : PageModel{ ???public void OnGet() ???{ ???} ???[BindProperty] ???public FileUpload FileUpload { get; set; } ???public async Task<IActionResult> OnPost() ???{ ???????var path = System.IO.Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, "Uploads"); ???????if (!System.IO.Directory.Exists(path)) ???????{ ???????????System.IO.Directory.CreateDirectory(path); ???????} ???????path = System.IO.Path.Combine(path, $"{DateTime.Now.ToString("yyyyMMddHHmmssfff")}_{FileUpload.FileData.FileName}"); ???????var fs = System.IO.File.Open(path, System.IO.FileMode.Create, System.IO.FileAccess.Write); ???????await FileUpload.FileData.CopyToAsync(fs); ???????fs.Close(); ???????fs.Dispose(); ???????return Page(); ???}}public class FileUpload{ ???[Required(ErrorMessage ="文件名不能为空")] ???[Display(Name ="文件名")] ???public string FileName { get; set; } ???[Required(ErrorMessage = "必须选择需要上传的文件")] ???[Display(Name ="选择文件")] ???public IFormFile FileData { get; set; }}Asp.Net Core 程序开发技巧汇总
原文地址：https://www.cnblogs.com/tianjiuyi/p/10212559.html