Is there any way to associate a "custom asset" with a particular file type?

[swquinn]

I've seen similar questions already asked, but none seemed to answer the core of my question, that is: is it possible to create a custom asset (i.e. an object extending `ScriptableObject`) and associate it with a specific file type?

As an example, if I have an object:

FooAsset.cs

using UnityEngine;

public class FooAsset : ScriptableObject {
  public Object _asset;
}

FooAssetEditor.cs

using UnityEditor;
using UnityEngine;

[CustomEditor(typeof(FooAsset))]
public class FooAssetEditor : Editor {
  protected FooAsset _fooAsset;

  public override void OnInspectorGUI() {
    _fooAsset = (FooAsset) target;
    _fooAsset.Asset = (Object) EditorGUILayout.ObjectField(
        "Foo File", _fooAsset.Asset, typeof(Object));
  }
}

Is there any way that upon using the `EditorGUILayout.ObjectField(...)` method, or some other combination of methods/GUI objects that can I associate the `_asset` field on `FooAsset` with a completely arbitrary file type (e.g. `.foo`) that resides underneath my Assets folder?

I have a very simple custom editor right now doing what I want with the `ObjectField(...)` method, except that I can't see assets of type `.foo` within its selection window. (NB: my actual extension, not `.foo`, identifies a binary file--specifically an archive containing xml data. I haven't quite figured out how to even work with the file once I get it loaded in the manner I would like to load it in, but I'll cross that bridge when I come to it).

Any help is appreciated, if you can point me to projects, tutorials, or snippets of code that I may have missed in my search, I'd be forever grateful!

---

If there is no "easy" way to accomplish the above using what is already in Unity, perhaps someone can point me in the right direction for what I will need to customize?

I suspect I will have to do some combination of the following to achieve a custom field editor with behavior similar to that of the ObjectField:

1. Create a custom editor which presents the user with a field (Drag-and-Drop enabled) to accept assets.
2. A file browser/asset selection window that targets specifically only the file type (or types) I'm looking for, but is not necessarily confined to a specific folder (e.g. Resources).

[Bunny83]

I still don’t fully understand the question. Arbitrary assets (ScriptableObjects) needs the extension “.asset”. You can’t use another extension, see AssetDatabase.CreateAsset.

Windows users (like myself) are used to the fact that the extension tells you the type of the file. Unity does it in a similar way but you have to see the situation from Unitys point of view. The assetdatabase is designed to handle the build-in types in the first place. The scriptable object is a way to store arbitrary data. Unity doesn’t care about the derived type, so it’s just an “asset”.

If you want to handle the assets based on the file name, give it a meaningful name. For example a scriptable object that contains an instance of FooAsset could be named like this:

"MyFoo.foo.asset", "MyFoo(foo).asset", "Foo_MyFoo.asset", ...

Now you can check the name (not the real file extension) for your additional extension or any other way to store the type information in the filename.

Unity supports only a few asset types. For example if you need any type of binary / text / xml asset you have to use “.txt” so it’s imported as TextAsset which is stored as it is in the project.