前言
昨天开源了业务业余时间自己封装的dapper lambda扩展，同时写了篇博文《编写自己的dapper lambda扩展-使用篇》简单的介绍了下其使用，今天将分享下它的设计思路
链式编程
其实就是将多个方法通过点（.）将它们串接起来,让代码更加简洁, 可读性更强。
new SqlConnection("").QuerySet<User>() .Where(a => a.Name == "aasdasd") .OrderBy(a => a.CreateTime) .Top(10) .Select(a => a.Name).ToList();
其原理是类的调用方法的返回值类型为类本身或其基类，选择返回基类的原因是为了做降
级约束，例如我希望使用了Top之后接着Select和ToList，无法再用where或orderBy。
UML图
原型代码
CommandSet
public class CommandSet<T> : IInsert<T>, ICommand<T> { #region 方法 public int Insert(T entity) { throw new NotImplementedException(); } public int Update(T entity) { throw new NotImplementedException(); } public int Update(Expression<Func<T, T>> updateExpression) { throw new NotImplementedException(); } public int Delete() { throw new NotImplementedException(); } public IInsert<T> IfNotExists(Expression<Func<T, bool>> predicate) { throw new NotImplementedException(); } public ICommand<T> Where(Expression<Func<T, bool>> predicate) { throw new NotImplementedException(); } #endregion } public interface ICommand<T> { int Update(T entity); int Update(Expression<Func<T, T>> updateExpression); int Delete(); } public interface IInsert<T> { int Insert(T entity); } public static class Database { public static QuerySet<T> QuerySet<T>(this SqlConnection sqlConnection) { return new QuerySet<T>(); } public static CommandSet<T> CommandSet<T>(this SqlConnection sqlConnection) { return new CommandSet<T>(); } }
QuerySet
public class QuerySet<T> : IAggregation<T> { #region 方法 public T Get() { throw new NotImplementedException(); } public List<T> ToList() { throw new NotImplementedException(); } public PageList<T> PageList(int pageIndex, int pageSize) { throw new NotImplementedException(); } public List<T> UpdateSelect(Expression<Func<T, T>> @where) { throw new NotImplementedException(); } public IQuery<TResult> Select<TResult>(Expression<Func<T, TResult>> selector) { throw new NotImplementedException(); } public IOption<T> Top(int num) { throw new NotImplementedException(); } public IOrder<T> OrderBy<TProperty>(Expression<Func<T, TProperty>> field) { throw new NotImplementedException(); } public IOrder<T> OrderByDescing<TProperty>(Expression<Func<T, TProperty>> field) { throw new NotImplementedException(); } public int Count() { throw new NotImplementedException(); } public bool Exists() { throw new NotImplementedException(); } public QuerySet<T> Where(Expression<Func<T, bool>> predicate) { throw new NotImplementedException(); } #endregion } public interface IAggregation<T> : IOrder<T> { int Count(); bool Exists(); } public interface IOrder<T> : IOption<T> { IOrder<T> OrderBy<TProperty>(Expression<Func<T, TProperty>> field); IOrder<T> OrderByDescing<TProperty>(Expression<Func<T, TProperty>> field); } public interface IOption<T> : IQuery<T>, IUpdateSelect<T> { IQuery<TResult> Select<TResult>(Expression<Func<T, TResult>> selector); IOption<T> Top(int num); } public interface IUpdateSelect<T> { List<T> UpdateSelect(Expression<Func<T, T>> where); } public interface IQuery<T> { T Get(); List<T> ToList(); PageList<T> PageList(int pageIndex, int pageSize); }
以上为基本的设计模型，具体实现如有问题可以查看我的源码。
