public class Person
{
public bool FirstNameIsActive { get; set; }
public bool SecondNameIsActive { get; set; }
}
List<Person> persons = new List<Person>();
public IEnumerable<Person> filter(string prop, bool isActive)
{
Func<Person, bool> predicate = null;
if (prop == "FirstNameIsActive")
predicate = x => x.FirstNameIsActive == isActive;
else if (prop == "SecondNameIsActive")
predicate = x => x.SecondNameIsActive == isActive;
return persons.Where(predicate);
}filter() ? То есть мне нужно что-то вродеpredicate = x => x.PROPERTY == isActive;
//property selector
Func<Person, Boolean> propertySelector = person => person.FirstNameIsActive;
//your predicate
Func<Person, Boolean> predicate = person => propertySelector(person) == true;
//new person with true, false properties.
Person p = new Person() {FirstNameIsActive = true,SecondNameIsActive = false};
Console.WriteLine(predicate(p).ToString()); //prints true
//change the property selector
propertySelector = person => person.SecondNameIsActive;
//now the predicate uses the new property selector
Console.WriteLine(predicate(p).ToString()); //prints falsepublic class Person
{
public bool FirstNameIsActive { get; set; }
public bool SecondNameIsActive { get; set; }
}
public List<Person> list = new List<Person>() {
new Person() {
FirstNameIsActive = true,
SecondNameIsActive = false
},
new Person() {
FirstNameIsActive = false,
SecondNameIsActive = true
}
};
private IQueryable<Person> Filter(PropertyInfo property, bool isActive)
{
IQueryable<Person> queryableData = list.AsQueryable<Person>();
//create input parameter
ParameterExpression inputParam = Expression.Parameter(typeof(Person));
//left contition
Expression left = Expression.Property(inputParam, property);
//right condition
Expression right = Expression.Constant(isActive, typeof(bool));
//equals
Expression e1 = Expression.Equal(left, right);
//create call
MethodCallExpression whereCallExpression = Expression.Call(
typeof(Queryable),
"Where",
new Type[] { queryableData.ElementType },
queryableData.Expression,
Expression.Lambda<Func<Person, bool>>(e1, new ParameterExpression[] { inputParam }));
//execute and return
return queryableData.Provider.CreateQuery<Person>(whereCallExpression);
}
private void test()
{
Filter(typeof(Person).GetProperty("FirstNameIsActive"), true);
Filter(typeof(Person).GetProperty("SecondNameIsActive"), true);
}