How to find object value in list

Question

I have a list of area object, how to find object value?

List<object> _area = new List<object>();
_area.Add(new { area_pid = _area_pid, info = _area_name });

I need to find area_pid in list if it is not found then it adds a new object.

This is a great use case for not using anonymous objects like this, C# is not JavaScript, if you simply created your self a class to hold this information and not use List — TheGeneral, May 14 '19 at 05:01

Caius Jard · Accepted Answer · 2019-05-14T05:18:33.060

If you can't be bothered creating a full on class for your area (and I don't see why not, it just seems to be a couple of properties, maybe 3 lines of code) you can use a ValueTuple

List<(int area_pid, string area_name)> areas = new List<(int, string)>();
areas.Add((3,"New York"));
areas.Add((4,"New Jersey"));
areas.Add((5,"Chicago"));

//find example
var newAreas = areas.Where(a => a.area_name.StartsWith("New"));

Personally I'm not a fan over creating a dedicated storage class, but it may be of interest to you. There are a c# 7 / .net 4.7 construct by the way

See for more:

https://blogs.msdn.microsoft.com/mazhou/2017/05/26/c-7-series-part-1-value-tuples/

How to create a List of ValueTuple?

I was just about to add ValueTuples +1 – TheGeneral May 14 '19 at 05:15 — TheGeneral, May 14 '19 at 05:15

TheGeneral · Answer 2 · 2019-05-14T05:11:10.997

4

Given

public class Something
{
   public Something(string area, string name)
   {
      Area = area;
      Name = name;
   }

   public string Area { get; set; }
   public string Name { get; set; }      
}

Usage

Then you could simply use a Where statement

var somethings = new List<Something>();
somethings.Add(new Something("sad", "bobo"));

var results = somethings.Where(x => x.Area == "asd");

Or if you assume there is only one SingleOrDefault or FirstOrDefault

var result = somethings.SingleOrDefault(x => x.Area == "asd");

edited May 14 '19 at 05:11

answered May 14 '19 at 05:05

TheGeneral

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This is the route I would go, even though I answered with some intro to the ValueTuple facility – Caius Jard May 14 '19 at 05:19

Tan Boon Jun · Answer 3 · 2019-05-14T05:21:55.613

0

Your can use

foreach(Object item in _area) {

  System.Reflection.PropertyInfo pi = item.GetType().GetProperty("name");
  String yourValue = (String)(pi.GetValue(item, null));
}

But, I suggest your to have a model (Class) to store.

edited May 14 '19 at 05:21

answered May 14 '19 at 05:06

Tan Boon Jun

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12

Anu Viswan · Answer 4 · 2019-05-14T05:22:19.273

0

Another option is to use ToList() method for defining _area.

var _area = new []{new { area_pid = _area_pid, info = _area_name}}.ToList();
_area.Add(new { area_pid = _area_pid2, info = _area_name2 });

Now you could use

_area.Where(x=>x.area_pid==1);

Update: Based on comment by Enigmativity,

var _area = new []{new { area_pid = default(int), info = default(string)}}.Take(0).ToList();
_area.Add(new { area_pid = _area_pid2, info = _area_name2 });

edited May 14 '19 at 05:22

answered May 14 '19 at 05:17

Anu Viswan

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If you had a `.Take(0)` before the `.ToList()` then this would be a great answer. – Enigmativity May 14 '19 at 05:18

4 Answers4