如何获取数组嵌套属性的propertyinfo

Question

How can i get the propertyinfo of array child property. How can i access OtherAddress property in customer[0]

List<Orders> order = new List<Orders>(); 

Customer[] cs = { new Customer { CustNum = 5, OtherAddress = "Hello" }, new Customer { CustNum = 986, OtherAddress = "Other" } };

Customer[] cso = { new Customer { OtherAddress = "T", CustNum = 5 }, new Customer { CustNum = 777, OtherAddress = "other" } };

order.Add(new Orders(code + 1, "ALFKI", i + 0, 2.3 * i, "Mumbari", "Berlin", cs));
order.Add(new Orders(code + 2, "ANATR", i + 2, 3.3 * i, "Sydney", "Madrid", cso));
order.Add(new Orders(code + 3, "ANTON", i + 1, 4.3 * i, "NY", "Cholchester", cs));
order.Add(new Orders(code + 4, "BLONP", i + 3, 5.3 * i, "LA", "Marseille", cso));
order.Add(new Orders(code + 5, "BOLID", i + 4, 6.3 * i, "Cochin", "Tsawassen", cs));

To access the table operation

complexData = "customer.0.OtherAddress".split('.'); 
type = typeof(orders);

PropertyInfo propInfo = type.GetProperty(complexData[0]);
for (var i = 1; i < complexData.Count(); i++)
{
    propInfo = propInfo.PropertyType.GetProperty(complexData[i]);
}
return propInfo.PropertyType;

Answer 1

Assuming you have classes like follows:

public class Customer
{
    public int CustNum { get; set; }
    public string OtherAddress { get; set; }
}

public class Orders
{
    public Orders(/* ..other parameters.. */ Customer[] customers)
    {
        this.CustomersArray = customers;
    }

    // I use name CustomersArray instead of Customer to make the answer
    // easier to read
    public Customer[] CustomersArray { get; set; }
}

Then you can get the Type of the Customer.OtherAddress property as follows:

var propInfo = typeof(Orders)
   .GetProperty("CustomersArray")  // Orders -> Orders.CustomersArray
   .PropertyType.GetElementType()  // Customer[] -> Customer
   .GetProperty("OtherAddress");   // Customer -> Customer.OtherAddress

The main point is how to get the Type of Customer form the property Orders.CustomersArray . Since the Type of Orders.CustomersArray is array, you have to use GetElementType() to get the Type of array item, then proceed further down the path.

The generalized code that can retrieve Type of Customer.OtherAddress given a string path looks like this:

var complexData = "CustomersArray.0.OtherAddress".Split('.');
var type = typeof(Orders);
PropertyInfo propInfo = null;

for (var i = 0 ; i < complexData.Length ; i++)
{
    if (complexData[i] == "0")
    {
        type = type.GetElementType();
    }
    else
    {
        propInfo = type.GetProperty(complexData[i]);
        type = propInfo.PropertyType;
    }
}

return propInfo.PropertyType;

Also note that I replaced .Count() with .Length in the for loop, because .Count() comes from Linq and it's an O(n) operation -- it performs a loop over the complexData array every iteration of the for loop, which makes your for loop O(N^2). But this is just a side note.

Answer 2

Here's a simple way you can do this-

class Customer
{
    public int ID { get; set; }
    public string Name { get; set; }
}

List<Customer> ls = new List<Customer>();
ls.Add(new Customer() { ID = 1, Name = "Name 1" });
ls.Add(new Customer() { ID = 2, Name = "Name 2" });

PropertyInfo info = ls[0].GetType().GetProperty("ID");

This is just an illustration. GetProperty(<name>) accepts property name in case sensitive format.

In your case you have to do something like this-

complexData = "Customer.0.OtherAddress".split('.'); 

PropertyInfo propInfo = cs[0].GetType().GetProperty(complexData[2]); //access cs through index

complexData[2] is the property name for OtherAddress . You can loop through the complexData to retrieve property info of other properties, but make sure you pass the property name correctly in case sensitive way.