如何将EntityFramework实体类转换为JSON字符串

前些天在转换EntityFramework实体类为JSON时出错，我想很多朋友肯定也有相同遭遇。下面这个自定义的转换参考了一些网上的资料，实际出处记不太清楚了，好像来自CSDN论坛，感谢这些达人们。中间遇到一些问题，自己改了一些地方，比如对DateTime?类型的处理。

 

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Collections;using System.Reflection;using System.Data.Objects.DataClasses;using Utility;namespace Utilities{ public static class EntityObjectExtensionMethods { #region 实体扩展方法 /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <returns></returns> public static String ToEntitiesJson(this EntityObject obj) { return new EntitiesTools().EntitiesToJson(obj, ""); } /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <param name="Include">获取子对象：使用，号分开</param> /// <returns></returns> public static String ToEntitiesJson(this EntityObject obj, String Include) { return new EntitiesTools().EntitiesToJson(obj, Include); } /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <returns></returns> public static String ToEntitiesJson(this IQueryable obj) { return new EntitiesTools().EntitiesToJson(obj, ""); } /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <param name="Include">获取子对象：使用，号分开</param> /// <returns></returns> public static String ToEntitiesJson(this IQueryable obj, String Include) { return new EntitiesTools().EntitiesToJson(obj, Include); } /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <param name="Include">获取子对象：使用，号分开</param> /// <returns></returns> public static String ToEntitiesJson(this IList obj, String Include) { return new EntitiesTools().EntitiesToJson(obj, Include); } #endregion } #region 转换实体信息为Json /// <summary> /// 转换实体信息为Json /// </summary> public class EntitiesTools { #region 转换实体信息为Json /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <param name="Include">获取子对象：使用，号分开</param> /// <returns></returns> public String EntitiesToJson(Object obj, String Include) { Type type = obj.GetType(); String sJosnString = ""; StringBuilder TempStringJson = new StringBuilder(); StringBuilder json = new StringBuilder(); switch (type.Name) { case "ObjectQuery`1": TempStringJson.Clear(); json.Append("["); foreach (Object _obj in obj as IQueryable) { TempStringJson.Append(EntitiesToJson(_obj, Include, 0)); TempStringJson.Append(","); } sJosnString = TempStringJson.ToString(); json.Append(sJosnString.Substring(0, sJosnString.Length - 1)); json.Append("]"); break; case "List`1": TempStringJson.Clear(); json.Append("["); foreach (Object _obj in obj as IList) { TempStringJson.Append(EntitiesToJson(_obj, Include, 0)); TempStringJson.Append(","); } sJosnString = TempStringJson.ToString(); json.Append(sJosnString.Substring(0, sJosnString.Length - 1)); json.Append("]"); break; default: json.Append(EntitiesToJson(obj, Include, 0)); break; } return json.ToString(); } /// <summary> /// 转换实体信息为Json /// </summary> /// <param name="obj">实体对象</param> /// <param name="Include">获取子对象：使用，号分开</param> /// <param name="Level">当前递归的层级</param> /// <returns></returns> private String EntitiesToJson(Object obj, String Include, int Level) { if (obj == null) { return null; } StringBuilder TempStringJson = new StringBuilder(); List<String> IncludeA = Include.Split(',').ToList<String>(); //需要排除的属性类型 List<String> ignoreEntityTypes = new List<String> { "EntityReference`1", "EntityState", "EntityKey", "EntitySetName" }; //实体集合 List<String> ListType = new List<String> { "EntityCollection`1" }; //数据类型(非实体集合类型) List<String> EntitesType = new List<String> { "Binary", "Boolean", "DateTime", "DateTimeOffset", "Decimal", "Double", "Guid", "Int16", "Int32", "Int64", "Single", "String", "Time" }; //未支持的数据类型 List<String> NotType = new List<String> { "Byte", "SByte" }; StringBuilder json = new StringBuilder(); json.Append("{"); Type type = obj.GetType(); PropertyInfo[] propertyInfoList = type.GetProperties(); string doubleQuote = "/""; #region 迭代属性 foreach (PropertyInfo _PropertyInfo in propertyInfoList) { #region 排除类型 if (ignoreEntityTypes.Contains(_PropertyInfo.PropertyType.Name)) { continue; } #endregion var propertyName = _PropertyInfo.Name; var propertyType = _PropertyInfo.PropertyType; var propertyValue = _PropertyInfo.GetValue(obj, null); try { #region 值=null if (propertyValue == null) { json.Append(doubleQuote + propertyName + doubleQuote + ":" + "null"); json.Append(","); continue; } #endregion #region 非实体集合类型 if (EntitesType.Contains(propertyValue.GetType().Name)) { try { TempStringJson.Clear(); TempStringJson.Append(doubleQuote + propertyName + doubleQuote + ":" + StringFormat(propertyValue, propertyType)); TempStringJson.Append(","); json.Append(TempStringJson); continue; } catch (Exception Err) { throw Err; } } #endregion #region 非Include对象 if (!IncludeA.Contains(propertyName)) { json.Append(doubleQuote + propertyName + doubleQuote + ":" + "null"); json.Append(","); continue; } #endregion #region 实体集合类型 if (ListType.Contains(propertyValue.GetType().Name) && Level == 0) { try { TempStringJson.Clear(); bool IsNull = true; //用来判断集合是否为空，待改善的方法 foreach (Object p in (IRelatedEnd)propertyValue) { IsNull = false; break; } if (IsNull) { TempStringJson.Append(doubleQuote + propertyName + doubleQuote + ":" + "null"); TempStringJson.Append(","); continue; } StringBuilder ListJosnString = new StringBuilder(); json.Append(doubleQuote + propertyName + doubleQuote + ":["); foreach (Object p in (IRelatedEnd)propertyValue) { String Child = EntitiesToJson(p, Include, 1); ListJosnString.Append(Child); ListJosnString.Append(","); } String sListJosnString = ListJosnString.ToString(); TempStringJson.Append(sListJosnString.Substring(0, sListJosnString.Length - 1)); TempStringJson.Append("]"); TempStringJson.Append(","); json.Append(TempStringJson); continue; } catch (Exception Err) { throw Err; } } #endregion #region 其他类型[应该只剩下实体对象了],有可能有没有考虑到的情况！ try { TempStringJson.Clear(); TempStringJson.Append(doubleQuote + propertyName + doubleQuote + ":" + EntitiesToJson(propertyValue, Include, 1)); TempStringJson.Append(","); json.Append(TempStringJson); continue; } catch (Exception Err) { throw Err; } #endregion } catch (Exception Err) { json.Append(doubleQuote + propertyName + doubleQuote + ":" + "null"); json.Append(","); continue; } } #endregion String sJosnString = json.ToString(); return sJosnString.Substring(0, sJosnString.Length - 1) + "}"; } private string StringFormat(object val, Type type) { string str = val.ToString(); if (type == typeof(string)) { str = String2Json(str); str = "/"" + str + "/""; } else if (type == typeof(DateTime) || Nullable.GetUnderlyingType(type) == typeof(DateTime)) { str = DateTimeUtils.DateNetToJs((DateTime)val); //str = "/" + str + ""; } else if (type == typeof(bool)) { str = str.ToLower(); } return str; } /// <summary> /// 过滤特殊字符 /// </summary> /// <param name="s"></param> /// <returns></returns> private static string String2Json(String s) { StringBuilder sb = new StringBuilder(); for (int i = 0; i < s.Length; i++) { char c = s.ToCharArray()[i]; switch (c) { case '/"': sb.Append("///""); break; case '//': sb.Append("////"); break; case '/': sb.Append("///"); break; case '/b': sb.Append("//b"); break; case '/f': sb.Append("//f"); break; case '/n': sb.Append("//n"); break; case '/r': sb.Append("//r"); break; case '/t': sb.Append("//t"); break; default: sb.Append(c); break; } } return sb.ToString(); } #endregion } #endregion}

 

使用，例如我的User是EF一个实体类，要将User转为JSON，可以：

//从数据库获取UserUser u = GetSingleUser(1);string json = u.ToEntitiesJson();