1、简介
今天给大家推荐个好的轮子，System.Linq.Dynamic.Core。我们都知道
数据库应用程序经常依赖于“动态SQL”，即在运行时通过程序逻辑构造的查询。拼接SQL容易造成SQL注入，普通的LINQ可以用表达式树来完成，但也比较麻烦。推荐System.Linq.Dynamic.Core用起来比较方便。
这是Microsoft程序集的.NET 4.0动态语言功能的.NET Core /标准端口。
使用此库，可以在iQueryTable上编写动态LINQ查询（基于字符串）：
var query = db.Customers
.Where("City == @0 and Orders.Count >= @1", "London", 10)
.OrderBy("CompanyName")
.Select("new(CompanyName as Name, Phone)");
2、使用
2.1、nuget
Install-PackageSystem.Linq.Dynamic.Core-Version1.2.5
2.2、常见方式
using System.Collections;
using System.Collections.Generic;
using System.Linq.Dynamic.Core.Tests.Helpers;
using System.Linq.Dynamic.Core.Tests.Helpers.Models;
using System.Linq.Expressions;
using System.Reflection;
namespace System.Linq.Dynamic.Core.ConsoleTestApp
{
public static class E
{
public static IQueryable GroupBy2
{
//LambdaExpression keyLambda = DynamicExpression.ParseLambda(source.ElementType, null, "new (Profile.Age)", null);
LambdaExpression x = (LambdaExpression)keyLambda2;
//return source.Provider.CreateQuery
// Expression.Call(
// typeof(Queryable), "GroupBy",
// new Type[] { source.ElementType, keySelector.Body.Type },
// new Expression[] { source.Expression, Expression.Quote(keySelector) }
// ));
return source.Provider.CreateQuery(
Expression.Call(
typeof(Queryable), "GroupBy",
new Type[] { source.ElementType, x.Body.Type },
new Expression[] { source.Expression, Expression.Quote(x) }));
}
}
public class Program
{
public static void Main(string[] args)
{
Console.WriteLine("--start");
DynamicProperty[] props = { new DynamicProperty("Name", typeof(string)), new DynamicProperty("Birthday", typeof(DateTime)) };
Type type = DynamicClassFactory.CreateType(props);
DynamicProperty[] props2 = { new DynamicProperty("Name", typeof(string)), new DynamicProperty("Birthday", typeof(DateTime)) };
Type type2 = DynamicClassFactory.CreateType(props2);
DynamicProperty[] props3 = { new DynamicProperty("Name", typeof(int)), new DynamicProperty("Birthday", typeof(DateTime)) };
Type type3 = DynamicClassFactory.CreateType(props3);
DynamicClass dynamicClass = Activator.CreateInstance(type) as DynamicClass;
dynamicClass.SetDynamicPropertyValue("Name", "Albert");
dynamicClass.SetDynamicPropertyValue("Birthday", new DateTime(1879, 3, 14));
Console.WriteLine(dynamicClass);
string n1 = dynamicClass["Name"] as string;
Console.WriteLine("dynamicClass[\"Name\"] = '" + n1 + "'");
dynamicClass["NameX"] = "x";
string n2 = dynamicClass["NameX"] as string;
Console.WriteLine("dynamicClass[\"NameX\"] = '" + n2 + "'");
//GroupByAndSelect_TestDynamicSelectMember();
//Select();
//TestDyn();
//ExpressionTests_Enum();
//Where();
//ExpressionTests_Sum();
Console.WriteLine("--end");
}
private static void GroupByAndSelect_TestDynamicSelectMember()
{
var testList = User.GenerateSampleModels(51).Where(u => u.Profile.Age < 23);
var qry = testList.AsQueryable();
var rrrr = qry.GroupBy2(x => new { x.Profile.Age });
var ll = rrrr.ToDynamicList();
var byAgeReturnAllReal = qry.GroupBy(x => new { x.Profile.Age }).ToList();
var r1 = byAgeReturnAllReal[0];
//var byAgeReturnOK = qry.GroupBy("Profile.Age").ToDynamicList();
// - [0] {System.Linq.Grouping<<>f__AnonymousType0
var byAgeReturnAll = qry.GroupBy("new (Profile.Age)").OrderBy("Key.Age").ToDynamicList();
var q1 = byAgeReturnAll[0];
var k = q1.Key;
int? age = k.Age;
foreach (var x in byAgeReturnAllReal.OrderBy(a => a.Key.Age))
{
Console.WriteLine($"age={x.Key.Age} : users={x.ToList().Count}");
}
foreach (var x in byAgeReturnAll)
{
Console.WriteLine($"age={x.Key.Age} : users={x}");
}
}
private static void TestDyn()
{
var user = new User { UserName = "x" };
dynamic userD = user;
string username = userD.UserName;
Console.WriteLine("..." + username);
}
public static void ExpressionTests_Enum()
{
//Arrange
var lst = new List
var qry = lst.AsQueryable();
//Act
var result1 = qry.Where("it < TestEnum.Var4");
var result2 = qry.Where("TestEnum.Var4 > it");
var result3 = qry.Where("it = Var5");
var result4 = qry.Where("it = @0", TestEnum.Var5);
var result5 = qry.Where("it = @0", 8);
//Assert
int idx = 0;
var ar1 = result1.ToArray();
foreach (var c in new[] { TestEnum.Var1, TestEnum.Var2, TestEnum.Var3 })
{
Console.Write("*");
Write((int)c, (int)ar1[idx]);
idx++;
}
idx = 0;
ar1 = result2.ToArray();
foreach (var c in new[] { TestEnum.Var1, TestEnum.Var2, TestEnum.Var3 })
{
Console.Write("*");
Write((int)c, (int)ar1[idx]);
idx++;
}
Write((int)TestEnum.Var5, (int)result3.Single());
Write((int)TestEnum.Var5, (int)result4.Single());
Write((int)TestEnum.Var5, (int)result5.Single());
}
public static void Where()
{
//Arrange
var testList = User.GenerateSampleModels(100, allowNullableProfiles: true);
var qry = testList.AsQueryable();
//Act
//var xxx = DynamicQueryable
var userById = qry.Where("Id=@0", testList[10].Id);
var userByUserName = qry.Where("UserName=\"User5\"");
var nullProfileCount = qry.Where("Profile=null");
var userByFirstName = qry.Where("Profile!=null && Profile.FirstName=@0", testList[1].Profile.FirstName);
//Assert
Write(testList[10], userById.Single());
Write(testList[5], userByUserName.Single());
Write(testList.Count(x => x.Profile == null), nullProfileCount.Count());
Write(testList[1], userByFirstName.Single());
}
public static void ExpressionTests_Sum()
{
//Arrange
int[] initValues = { 1, 2, 3, 4, 5 };
var qry = initValues.AsQueryable().Select(x => new { strValue = "str", intValue = x }).GroupBy(x => x.strValue);
//Act
var result = qry.Select("Sum(intValue)").AsEnumerable().ToArray()[0];
//Assert
Write(15, result);
}
public static void Select()
{
//Arrange
List
var testList = User.GenerateSampleModels(100);
var qry = testList.AsQueryable();
//Act
IEnumerable rangeResult = range.AsQueryable().Select("it * it");
var userNames = qry.Select("UserName");
var userFirstName = qry.Select("new (UserName, Profile.FirstName as MyFirstName)");
var userRoles = qry.Select("new (UserName, Roles.Select(Id) AS RoleIds)");
//Assert
WriteArray(range.Select(x => x * x).ToArray(), rangeResult.Cast
WriteArray(testList.Select(x => x.UserName).ToArray(), userNames.ToDynamicArray());
WriteArray(testList.Select(x => "{UserName=" + x.UserName + ", MyFirstName=" + x.Profile.FirstName + "}").ToArray(), userFirstName.AsEnumerable().Select(x => x.ToString()).ToArray());
Guid[] check = testList[0].Roles.Select(x => x.Id).ToArray();
//dynamic f = userRoles.First();
//Guid[] ids = f.RoleIds.ToArray();
var userRole = userRoles.First();
Console.WriteLine(">>>>>>>>>>>>>>>>>>" + userRole.ToString());
PropertyInfo[] props = userRole.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public);
Console.WriteLine(">>>>>>>>>>>>>>>>>> GetProperties = {0}", string.Join(", ", props.Select(p => p.Name)));
Console.WriteLine(">>>>>>>>>>>>>>>>>> GetPropertyValues = {0}", string.Join(", ", props.Select(p => p.GetValue(userRole, null))));
string name = userRole.UserName;
Guid[] result = Enumerable.ToArray(userRole.RoleIds ?? new object[0]);
WriteArray(check, result);
}
private static void Write
{
Console.WriteLine("> '{0}'", check == result);
}
private static void Write(int check, int result)
{
Console.WriteLine("> {0} == {1} = '{2}'", check, result, check == result);
}
private static void WriteArray
{
for (int i = 0; i < check.Length; i++)
{
Console.WriteLine("> {0} : c={1}, r={2} '{3}'", i, check[i], result[i], check[i] == result[i]);
}
}
private static void WriteArray(Guid[] check, Guid[] result)
{
for (int i = 0; i < check.Length; i++)
{
Console.WriteLine("> {0} : c={1}, r={2} '{3}'", i, check[i], result[i], check[i] == result[i]);
}
}
private static void WriteArray(int[] check, int[] result)
{
for (int i = 0; i < check.Length; i++)
{
Console.WriteLine("> {0} : c={1}, r={2} '{3}'", i, check[i], result[i], check[i] == result[i]);
}
}
}
}
开源地址：
https://github.com/zzzprojects/System.Linq.Dynamic.Core
https://www.nuget.org/packages/System.Linq.Dynamic.Core