使用LINQ.Dynamic过滤空属性抛出异常

Question

我正在使用Linq.Dynamic，我有层列表（字符串Matricule，字符串名称..）虽然有些层没有Matricule，但是当运行LINQ在哪里Matricule属性，System.NullReferenceException：未将对象引用设置为对象的实例是否被抛出？ 这里是代码的细节：

public class Tier 
{ 
    public string Matricule{get;set;} 
    public string Nom{get;set;} 
    public string Prenom{get;set;} 
} 

public class FilterByPredicate 
    { 
     public BindingList<T> Filter(string propName,string propValue,bool fromFirst) 
      { 

       var predicateString = fromFirst 
           ? "{0}.ToString().ToUpper().StartsWith(@{1})" 
           : "{0}ToString().ToUpper().Contains(@{1})"; 

       return new BindingList<T>(_list.Where(string.Format(predicateString, propName, 0), propValue.ToUpper()).ToList()); 
      } 

    } 


in other part of my code i call.. 
    FilterByPredicate fbp = new FilterByPredicate(costumersList>); 
    textBox1_Changed+= 
    { 
     tiersBindingSource.DataSource =fbp .Filter("Matricule", textBox1.Text,true);// exception throwed 

//but this work fine-> var q = from c in costumersList where c.Matricule.ToUpper().StartsWith(textBox1.Text) select c; 
    }; 

Answer 1

我已经找到了解决办法阅读文档后，相应的“开始使用”页面，只需比较空这样的：

public BindingList<T> Filter(string propName,string propValue,bool fromFirst) 
      { 

       var predicateString = fromFirst 
           ? "{0} != null and {0}.ToString().ToUpper().StartsWith(@{1})" 
           : "{0} != null and {0}.ToString().ToUpper().Contains(@{1})"; 

       return new BindingList<T>(_list.Where(string.Format(predicateString, propName, 0), propValue.ToUpper()).ToList()); 
      }