c# – 使用参数在expression.call中调用静态方法

概述我已经扩展了Contains方法的字符串类.我试图在Expression.Call中调用它,但如何正确传递参数？ 代码：String包含方法： public static class StringExts{ public static bool NewContains(this string source, string ValToCheck, StringComparison StrC 我已经扩展了Contains方法的字符串类.我试图在Expression.Call中调用它,但如何正确传递参数？

代码：String包含方法：

public static class StringExts{    public static bool NewContains(this string source,string Valtocheck,StringComparison StrComp)    {        return source.IndexOf(Valtocheck,StrComp) >= 0;    }}

在表达式中调用为：

public class Person { public string name {get; set;} }public class Persons {     public List<Person> lstPersons {get; set;}     public Persons() {      lstPersons = new List<Person>();        }}public class Filter {    public string ID { get; set; }    public Operator Operator { get; set; }    public string value { get; set; }}public voID Main(){   //Get the Json.   //"Filters": [{"ID": "name","operator": "contains","value": "Microsoft"}]    Filter Rules = JsonConvert.DeserializeObject<Filter>(Json);   // Get the List of person firstname.    List<Person> lstPerson = GetFirstname();   ParameterExpression param = Expression.Parameter(typeof(Person),"p");   Expression exp = null;   exp = GetExpression(param,rules[0]);   //get all the name contains "john" or "John"   var filteredCollection = lstPerson.Where(exp).ToList();}private Expression GetExpression(ParameterExpression param,Filter filter){   MemberExpression member = Expression.Property(param,filter.ID);   ConstantExpression constant = Expression.Constant(filter.value);   Expression bEXP = null;   switch (filter.Operator)    {         case Operator.contains:           MethodInfo miContain = typeof(StringExts).getmethod("NewContains",BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);           return  Expression.Call(miContain,member,constant,Expression.Constant(StringComparison.OrdinalignoreCase));;            break;    } }

错误：

An unhandled exception of type ‘System.ArgumentException’ occurred in System.Core.dll.Additional information: Static method requires null instance,non-static method requires non-null instance.

@H_403_15@

如何调用miContain中的参数来跟随Call()方法？

我已经更新了守则.

解决方法 您没有指定所有参数.如果为所有人创建表达式,它可以工作：

ParameterExpression source = Expression.Parameter(typeof(string));string Valtocheck = "A";StringComparison StrComp = StringComparison.CurrentCultureIgnoreCase;MethodInfo miContain = typeof(StringExts).getmethod("NewContains",BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);var bEXP = Expression.Call(miContain,source,Expression.Constant(Valtocheck),Expression.Constant(StrComp));var lambda = Expression.Lambda<Func<string,bool>>(bEXP,source);bool b = lambda.Compile().Invoke("a");

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