思路分析

众所周知，利用反射可以在程序运行时获取到任一对象的类型、属性、参数、方法等，并加以调用，利用这些获取到的可以在程序运行时追加各种自定义的功能。以CRUD为例，我们可以利用反射获取到所有的Model并编写代码模板，最终达成用代码生成代码的结果。思路既然能走通，开搞开搞~

编码阶段

首先要确定生成哪些代码。CRUD每天都在做，但大部分都一样，这就导致每天有些时间都在板砖，毫无意义。所以我们需要自动生成全库的CRUD代码。

首先要写一个CRUD的模板代码，考虑到ORM框架太多，这里就以SqlSugar为例：

　　　　 [HttpGet]public async Task<IActionResult> GetList(int index = 1, int size = 15){RefAsync<int> count = 0;return PageMsg(await _sqlHelper.DB.Queryable<Models.AD>().OrderBy(x => x.Weight).ToPageListAsync(index, size, count), count.Value);}[HttpPost, Role("添加广告")]public async Task<IActionResult> Add([FromForm] Models.AD ad){Models.AD add = await _sqlHelper.DB.Insertable(ad).RemoveDataCache().ExecuteReturnEntityAsync();return Ok(add);}[HttpPut, Role("修改广告")]public async Task<IActionResult> Cag([FromForm] Models.AD ad){int result = await _sqlHelper.DB.Updateable(ad).RemoveDataCache().ExecuteCommandAsync();return YesOrNo(result > 0);}[HttpDelete]public async Task<IActionResult> Delete([FromForm] int id){int result = await _sqlHelper.DB.Deleteable<Models.AD>().Where(x => x.ID == id).ExecuteCommandAsync();return YesOrNo(result > 0);}

能看出这是一组操作AD类的CRUD，接下来就是需要把上面的模板封装起来，AD这种表的名称作为变量输入即可，如果想控制代码文件的路径，也可以作为参数传入。完整版：

　　　　　public void Make(string tableName, string path){if (!Directory.Exists(path))Directory.CreateDirectory(path);using FileStream fs = new FileStream($"{path}/{tableName}Controller.cs", FileMode.Append);System.Text.StringBuilder sb = new System.Text.StringBuilder();sb.Append("using System.Threading.Tasks;");sb.Append("\n");sb.Append("using XXXX.Services.DB;");sb.Append("\n");sb.Append("using Microsoft.AspNetCore.Authorization;");sb.Append("\n");sb.Append("using Microsoft.AspNetCore.Mvc;");sb.Append("\n");sb.Append("using SqlSugar;");sb.Append("\n");sb.Append("namespace XXXX.Controllers.v1");sb.Append("\n");sb.Append("{");sb.Append("\n");sb.Append("     [ApiController, Route(\"v1/[controller]/[action]\"), Authorize]");sb.Append("\n");sb.Append($"     public class {tableName}Controller : BaseController");sb.Append("\n");sb.Append("     {");sb.Append("\n");sb.Append("         private readonly SqlHelper _sqlHelper;");sb.Append("\n");sb.Append($"        public {tableName}Controller(SqlHelper sqlHelper)");sb.Append("\n");sb.Append("         {");sb.Append("\n");sb.Append("             _sqlHelper = sqlHelper;");sb.Append("\n");sb.Append("         }");sb.Append("\n");sb.Append("         [HttpGet]");sb.Append("\n");sb.Append($"         public async Task<IActionResult> GetList(int index = 1, int size = 15)");sb.Append("\n");sb.Append("         {");sb.Append("\n");sb.Append($"            RefAsync<int> count = 0;");sb.Append("\n");sb.Append("             return Ok(new{");sb.Append("\n");sb.Append($"               rows = await _sqlHelper.DB.Queryable<Models.{tableName}>().ToPageListAsync(index, size, count),");sb.Append("\n");sb.Append("                total = count.Value");sb.Append("\n");sb.Append("             });");sb.Append("\n");sb.Append("         }");sb.Append("\n");sb.Append("         [HttpPost]");sb.Append("\n");sb.Append($"         public async Task<IActionResult> Add([FromForm] Models.{tableName} {tableName.ToLower()})");sb.Append("\n");sb.Append("         {");sb.Append("\n");sb.Append($"             Models.{tableName} add = await _sqlHelper.DB.Insertable({tableName.ToLower()}).RemoveDataCache().ExecuteReturnEntityAsync();");sb.Append("\n");sb.Append("              return Ok(add);");sb.Append("\n");sb.Append("         }");sb.Append("\n");sb.Append("         [HttpPut]");sb.Append("\n");sb.Append($"         public async Task<IActionResult> Cag([FromForm] Models.{tableName} {tableName.ToLower()})");sb.Append("\n");sb.Append("         {");sb.Append("\n");sb.Append($"             int result = await _sqlHelper.DB.Updateable({tableName.ToLower()}).RemoveDataCache().ExecuteCommandAsync();");sb.Append("\n");sb.Append("              return YesOrNo(result>0);");sb.Append("\n");sb.Append("         }");sb.Append("\n");sb.Append("         [HttpDelete]");sb.Append("\n");sb.Append($"         public async Task<IActionResult> Cag([FromForm] int id)");sb.Append("\n");sb.Append("         {");sb.Append("\n");sb.Append($"             int result = await _sqlHelper.DB.Deleteable<Models.{tableName}>().Where(x => x.ID == id).ExecuteCommandAsync();");sb.Append("\n");sb.Append("              return YesOrNo(result>0);");sb.Append("\n");sb.Append("         }");sb.Append("\n");sb.Append("     }");sb.Append("\n");sb.Append("}");using StreamWriter sw = new StreamWriter(fs);sw.WriteLine(sb.ToString());}

为了方便理解，刻意美化了一下。

OK，代码模板搞好了，该从哪里拿到所有的Model呢？思路是先加载程序集，然后找到存放Model的命名空间，然后找到命名空间下面所有符合条件的Class，然后就可以拿到具体的名称，从而调用代码模板进行文件生成，像这样：

　　　　　　　var assembly = Assembly.Load("程序集名称");var types = assembly.ExportedTypes.Where(a => a.FullName.Contains("Model所处的命名空间")).ToList();//指定string path = $"{Directory.GetCurrentDirectory()}/autoCode";foreach (var item in types){string tableName = item.FullName.Split('.')[^1];Make(tableName, path);}

接下来直接运行，走完以后的结果是这样的：

随便打开一个文件，是这样的：

效果还是不错的。

如果需要更加精细的控制，可以预先在Model设置特性，然后通过判断特性是否存在来决定如何生成代码，举个栗子：

　　　　　　　var assembly = Assembly.Load("程序集名称");var types = assembly.ExportedTypes.Where(a => a.FullName.Contains("Model所处的命名空间")).ToList();//指定string path = $"{Directory.GetCurrentDirectory()}/autoCode";foreach (var item in types){//获取所有公开属性foreach (var prop in item.GetProperties()){MyAttribute attr = method.GetCustomAttribute(typeof(MyAttribute), true) as MyAttribute;if(attr is null){//进入这里代表该属性没有附加 MyAttribute}}}