Check properties of object is null

Question

I have List of Albums objects (photo albums for example). I check properties of the object is null.

Just example:

if (albums.Last() != null 
      && albums.Last().Photos != null 
      && albums.Last().Photos.Description != null) { //action }

Can I do this check shorter in code?

You can use combination of expressions and Reflection - here is my complete code for this http://stackoverflow.com/questions/429112/how-can-i-manage-the-onslaught-of-null-checks/20434899#20434899 — Konrad Kokosa, Jul 02 '14 at 05:35
What about `try { //action } catch (NullReferenceException){}`? I guess its not good practice to ignore exceptions? — DerApe, Jul 02 '14 at 05:42
@derape: you centainly don't want the overhead of exception handling for something simple like this. — Patrick Hofman, Jul 02 '14 at 05:43
Why don't create a Method to handle this in the object itself? — MarmiK, Jul 02 '14 at 06:22

score 4 · Answer 1 · answered Jul 02 '14 at 05:34

Just wrap it in a function:

public static bool IsInitialized(a Album) {
    return a != null &&
        a.Photos != null &&
        a.Photos.Description != null;
}

Then your calling code becomes:

var album = albums.LastOrDefault();

if (Album.IsInitialized(album)) {
    // its fine
}

Amir Popovich · Accepted Answer · 2014-07-02T05:38:15.237

2

You can't.

BTW:

use vars instead of calling a function all the time(Last()).

use LastOrDefault() and prevent crashes.

var lastAlbum = albums.LastOrDefault();
if(lastAlbum != null && lastAlbum.Photos != null && lastAlbum.Photos.Description != null){//action}

edited Jul 02 '14 at 05:38

answered Jul 02 '14 at 05:35

Amir Popovich

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brainless coder · Answer 3 · 2014-07-02T05:55:09.420

2

You could use an Extension Method -

public static class ListExtension {
     public static bool IsLastPhotoNotNull(this List<Album> albums){
          var album = albums.LastOrDefault();
          return album != null && album.Photos != null && album.Photos.Description != null;
     }
}

Then call it with the list

List<Album> albums;

if(!albums.IsLastPhotoNotNull()){
    //...do other actions
}

edited Jul 02 '14 at 05:55

answered Jul 02 '14 at 05:42

brainless coder

6,310
1
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36

score 1 · Answer 4 · answered Jul 02 '14 at 05:35

Shorter, no. But more efficient, yes.

You are calling the Last() method multiple times. That could harm performance if there are for example database actions involved in that call.

Pull the method outside the if:

var last = albums.Last();
if (last != null 
  && last.Photos != null 
  && last.Photos.Description != null)
{ //action }

Check properties of object is null

4 Answers4