Question

在类似这样的方法中：

public List<Teachers> GetEligibleTeachers(string fieldname)
{
  var query = from t in this.Context.Teachers
              // some more joins and logic , etc..
              where t.custom_field == true
 // .... rest of the query
}

我已经将where子句中的字段名称硬编码为custom_field但是有一种方法可以将其作为参数传递给我的方法吗？例如，可能有a.custom_field , a.field2 , a.teahcer_id , etc....

Answer 1

您可以通过创建更高阶函数（请参阅Refactor methods - pass in property name）来完成此操作

public List<Teachers> GetTeachers()
{
    return GetEligibleTeachers(x => x.fieldname);
}

public List<Teachers> GetEligibleTeachers(Func<Teachers, bool> elementIdentity)
{
   var query = Context.Teachers.Where(elementIdentity == true) // rest of query
}

Answer 2

你可以使用这样的东西：

public List<Teachers> GetEligibleTeachers(Func<Teachers, bool> predicate)
{
  var query = this.Context.Teachers.Where(predicate);
 // .... rest of the query
}

并称之为：

var result = GetEligibleTeachers(t => t.SomeField == "SomeValue");

将字段名称传递给linq查询

2 个答案: