[Resolved] Dictionary in Scriptable Object using Ryan Hipple Method

What I'm trying to do is create a Scriptable Object script for Dictionaries for the most part I got it working except for one part.

I can't call to get a value from dictionary with a key

Here is all my code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public abstract class RuntimeTable<TKey, TValue> : ScriptableObject
6. {
7.     public Dictionary<TKey, TValue> KeyPair = new Dictionary<TKey, TValue>();
8.  
9.     public void Add(TKey key, TValue value)
10.     {
11.         if(!KeyPair.ContainsKey(key)){
12.             KeyPair.Add(key, value);
13.         }
14.     }
15.  
16.     public void Remove(TKey key)
17.     {
18.         if(KeyPair.ContainsKey(key)){
19.             KeyPair.Remove(key);
20.         }
21.     }
22. }
23.  

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. [CreateAssetMenu(fileName = "GeneralTable", menuName = "Data/Tables/General")]
6. public class GeneralRuntimeTable : RuntimeTable<string, string>
7. {}
8.  

Code (CSharp):

1. public class MyScript : MonoBehaviour {
2.  
3.     public GeneralRuntimeTable myTable;
4.  
5.     void Start(){
6.         string catName = myTable["name"];
7.     }
8. }

I can't get myTable["name"] to work it keeps outputting an error

Cannot apply indexing with [] to an expression of type 'GeneralRuntimeTable' [Assembly-CSharp, Assembly-CSharp-Editor]

Only assignment, call, increment, decrement, and new object expressions can be used as a statement [Assembly-CSharp, Assembly-CSharp-Editor]

If you haven't seen or understand Ryan Hipple's talk at Unite Austin 2017 then go watch it.

https://github.com/roboryantron/Unite2017

 

Just a guess (didn't look at the video) but does your RuntimeTable perhaps have to also implement the IDictionary interface? Judging from this:

https://msdn.microsoft.com/en-us/library/s4ys34ea(v=vs.110).aspx

That is what implements the indexing operator.

 

Do you have an example on how I would do this? I'm still very much a C# beginner.

 

Your code inherits from ScriptableObject, and not a dictionary.
Inside the class is a dictionary.

 

It has to inherit from ScriptableObject. That's the the method works.

 

Sure, I get that that's your goal. What I was saying is that scriptable object doesn't have an indexer defined. So, you either have to use your methods, access the dictionary itself and use the indexer, or as mentioned implement an interface and complete it to do the same.

 

Perfect! Thanks for the help!

Working Code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public interface IRuntimeTable<TKey, TValue>{
6.     TValue this[TKey key]{
7.         get;
8.         set;
9.     }
10. }
11.  
12. public abstract class RuntimeTable<TKey, TValue> : ScriptableObject, IRuntimeTable<TKey, TValue>
13. {
14.     public Dictionary<TKey, TValue> KeyPair = new Dictionary<TKey, TValue>();
15.  
16.     public void Add(TKey key, TValue value)
17.     {
18.         if(!KeyPair.ContainsKey(key)){
19.             KeyPair.Add(key, value);
20.         }
21.     }
22.  
23.     public void Remove(TKey key)
24.     {
25.         if(KeyPair.ContainsKey(key)){
26.             KeyPair.Remove(key);
27.         }
28.     }
29.  
30.     public TValue this[TKey key]{
31.         get{
32.             return KeyPair[key];
33.         }
34.         set{
35.             KeyPair[key] = value;
36.         }
37.     }
38. }

 

Getting new error now:

ArgumentNullException: Value cannot be null.

Parameter name: key

System.Collections.Generic.Dictionary`2[TKey,TValue].FindEntry (TKey key) (at <e1a80661d61443feb3dbdaac88eeb776>:0)

System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) (at <e1a80661d61443feb3dbdaac88eeb776>:0)

RuntimeTable`2[TKey,TValue].get_Item (TKey key) (at Assets/BuilderScripts/Tables/RuntimeTable.cs:32)

 

And the code creating the error is? Passing 'null' as a key?

 

I derped .....I had issue with declaring variables.

It works perfectly now. Thanks again methos5k you've been a big help!

This thread is officially resolved

 

Hi Ryan, could you please share the script accessing the Table? "MyTable" with the cat string. Thanks a lot!