返回类的所有属性，而不是null c＃

Question

I've been looking and found this which describes to return a bool if value is null . The code, I'm using is from this snippet Client client = new Client{ FirstName = "James"};

client.GetType().GetProperties()
.Where(pi => pi.GetValue(client) is string)
.Select(pi => (string) pi.GetValue(client))
.Any(value => string.IsNullOrEmpty(value));

But instead of returning if the value is null or not (the bool) I would like to retrieve all the properties values where they are not null.

I've tried making changes to the code, but unsuccessful.

Many thanks

EDIT

public class Client
{
   public string FirstName { get; set; }
   public string LastName { get; set; }
   //...
}

Client client = new Client();
client.FirstName = "James";
client.LastName = "";

Using my 'Client' class, I would like to iterate over all the properties within my class, and where the value isn't null or empty string, I would return the value, in this example, I would only return a string "James".

Hope that makes sense.

Answer 1

There are some issues:

return myObject.GetType().GetProperties()
.Where(pi => pi.GetValue(myObject) is string) // this wastes time getting the value
.Select(pi => (string) pi.GetValue(myObject))
.Any(value => string.IsNullOrEmpty(value)); //  Any will return a bool

So change this to:

return myObject.GetType().GetProperties()
.Where(pi => pi.PropertyType == typeof(string)) // check type
.Select(pi => (string)pi.GetValue(myObject)) // get the values
.Where(value => !string.IsNullOrEmpty(value)); // filter the result (note the !)

Also, ensure that your properties are properties and not fields.

Answer 2

Use Where instead of Any . Also you were missing an ! at !string.IsNullOrEmpty(value) .

I modified your code to return a dictionary with property values indexed by name.

var stringPropertyValuesByName = client.GetType().GetProperties()
    .Where(pi => pi.PropertyType == typeof(string)) // use type check as Steve Harris suggested 
    .Select(pi => new { Val = (string) pi.GetValue(client), Name = pi.Name })
    .Where(pi => !string.IsNullOrEmpty(pi.Val))
    .ToDictionary(pi => pi.Name, pi => pi.Val);

C# Fiddle

Answer 3

If you want to get all not null properties that are also not empty strings i suggest:

using System;
using System.Linq;

class Cls
{
    public string Prop1 {get; set;}

    public object Prop2 {get; set;}

    public int Prop3 {get; set;}

    public string Prop4 {get; set;}

}

public class Program
{
    public static void Main()
    {
        var obj = new Cls() { Prop1 = "abc", Prop3 = 5 };

        var props = obj
            .GetType()
            .GetProperties()
            .Select(p => p.GetValue(obj))
            .Where(x => x != null || ( x is string && (string)x != ""))
            .ToList();

        Console.WriteLine(string.Join(",", props));
    }
}

produces:

abc,5