In Unity development, we often need to store key-value pairs of data, and Dictionary is one of the most efficient data structures to achieve this. However, one of the limitations of Unity’s default inspector is that it does not display Dictionary contents directly, which can be a hassle during development, especially when we want to inspect, modify, or debug dictionary data. In this article, we will explore a clean solution to display a Dictionary in Unity’s Inspector, helping you improve your workflow and streamline data management within the Unity Editor.

1. Why Should You Display a Dictionary in the Inspector?

A Dictionary in C# allows you to store data as key-value pairs, providing an easy way to retrieve values based on their corresponding keys. This structure is useful when you need fast lookups, such as managing game settings, configurations, player stats, or item inventories.

However, Unity’s default Inspector does not natively support Dictionary serialization, which means that you can’t directly view or modify the dictionary data in the Unity Editor. Without being able to easily inspect dictionary contents, debugging and data modification can become tedious and error-prone. Displaying a Dictionary in the Inspector enables:

  • Easier debugging: Quickly check the contents of the dictionary while the game is running.
  • Real-time editing: Adjust dictionary values directly in the editor.
  • Enhanced workflow: Spend less time manually logging data and more time optimizing game features.

2. How to Display a Dictionary in Unity’s Inspector

There are several ways to make Dictionary data visible in the Inspector. The most efficient approach is to use Custom Property Drawers and Serializable Lists as intermediaries. By serializing the keys and values as Lists, Unity can serialize them, and we can draw these lists with custom functionality. Below, we will walk through the process in detail.

2.1 Creating the Custom Property Drawer

We need to create a Custom Property Drawer to render our dictionary keys and values in the inspector. Unity’s PropertyDrawer class allows you to customize how specific properties are displayed.

To start, we’ll create a custom drawer that will allow the keys and values to be serialized and displayed as Lists.

using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

[CustomPropertyDrawer(typeof(MyDictionary))]
public class DictionaryDrawer : PropertyDrawer
{
    // This method controls the appearance of the dictionary in the inspector.
    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        // Get the keys and values lists from the serialized dictionary
        SerializedProperty keys = property.FindPropertyRelative("keys");
        SerializedProperty values = property.FindPropertyRelative("values");

        // Draw the keys and values as lists
        EditorGUI.PropertyField(new Rect(position.x, position.y, position.width, 20), keys);
        EditorGUI.PropertyField(new Rect(position.x, position.y + 25, position.width, 20), values);

        // Optionally, you can add custom logic for handling specific data
        if (keys.arraySize != values.arraySize)
        {
            EditorGUI.HelpBox(new Rect(position.x, position.y + 50, position.width, 20),
                "Keys and Values do not match in size", MessageType.Warning);
        }
    }
}

2.2 Creating the MyDictionary Class

Now we need to create the class that will store our Dictionary data. Since Unity doesn’t natively support serializing Dictionaries, we’ll serialize them as Lists. The keys and values will be stored as separate lists, and we’ll use these lists to mimic the behavior of a dictionary.

[System.Serializable]
public class MyDictionary
{
    // We serialize the keys and values as Lists so Unity can handle them in the inspector
    public List<string> keys = new List<string>();
    public List<int> values = new List<int>();

    // Add a new key-value pair to the dictionary
    public void Add(string key, int value)
    {
        keys.Add(key);
        values.Add(value);
    }

    // Retrieve a value based on the key
    public int GetValue(string key)
    {
        int index = keys.IndexOf(key);
        return (index >= 0) ? values[index] : -1; // Return -1 if key doesn't exist
    }

    // Remove a key-value pair
    public void Remove(string key)
    {
        int index = keys.IndexOf(key);
        if (index >= 0)
        {
            keys.RemoveAt(index);
            values.RemoveAt(index);
        }
    }

    // Check if the dictionary contains a specific key
    public bool ContainsKey(string key)
    {
        return keys.Contains(key);
    }

    // Get the number of elements in the dictionary
    public int Count()
    {
        return keys.Count;
    }
}

2.3 Using the Dictionary in a MonoBehaviour Class

Now we will use the MyDictionary class inside a MonoBehaviour to store key-value pairs. When we attach this class to a GameObject, Unity’s Inspector will allow us to view and modify the dictionary contents.

public class GameSettings : MonoBehaviour
{
    public MyDictionary settings = new MyDictionary();

    void Start()
    {
        // Adding some initial values
        settings.Add("PlayerHealth", 100);
        settings.Add("EnemyDamage", 25);
        settings.Add("MovementSpeed", 5);
    }
}

3. Advantages and Disadvantages

3.1 Advantages

  1. Real-time Editor Access: By displaying Dictionary contents in the Inspector, developers can quickly inspect and modify values without needing to write custom logging or data visualization code.
  2. Easy Debugging: It simplifies debugging, as developers can immediately see and adjust data related to game settings or states directly within the Unity Editor.
  3. Flexible and Scalable: This method works for various types of Dictionaries. You can adjust it for different key and value types (e.g., string to int, string to float, etc.).
  4. Simplifies Workflows: You can manage complex datasets like game configuration settings, player stats, or even quest progression directly in the editor.

3.2 Disadvantages

  1. Complexity of Setup: This approach requires writing a custom drawer and managing the serialized lists, which can add some complexity to the project setup.
  2. Performance Considerations: Serializing large amounts of data in Lists may introduce some performance overhead, especially for games with a vast amount of data stored in dictionaries.
  3. Not Native to Unity: Since Unity doesn’t natively support Dictionary serialization, this workaround may not be as intuitive as working with other data types directly supported by Unity.

4. Use Cases and Real-world Applications

4.1 Managing Game Settings

You could use this method to manage various game settings such as audio levels, graphics options, and other configuration data. Displaying these settings as a Dictionary in the inspector would allow designers to tweak settings quickly without needing to dive into the code.

public class GameSettings : MonoBehaviour
{
    public MyDictionary settings = new MyDictionary();

    void Start()
    {
        settings.Add("AudioVolume", 80);
        settings.Add("GraphicsQuality", 3);
        settings.Add("FullScreen", 1);
    }
}

4.2 Storing and Modifying Player Stats

Another practical example is using a Dictionary to store player stats. With the dictionary displayed in the inspector, you can easily modify player attributes like health, attack power, or movement speed without manually changing the code or using external tools.

public class PlayerStats : MonoBehaviour
{
    public MyDictionary playerStats = new MyDictionary();

    void Start()
    {
        playerStats.Add("Health", 100);
        playerStats.Add("Attack", 50);
        playerStats.Add("Defense", 30);
    }
}

4.3 Dynamic Game Content

For dynamic content such as a quest system, where each quest has its unique conditions and rewards, you can use a Dictionary to store quest IDs and their associated data. This would enable designers to easily adjust and debug the quests in the editor.

public class QuestSystem : MonoBehaviour
{
    public MyDictionary quests = new MyDictionary();

    void Start()
    {
        quests.Add("Quest1", 100); // Quest1 requires 100 points to complete
        quests.Add("Quest2", 200); // Quest2 requires 200 points
    }
}

5. Conclusion

In this article, we explored how to display a Dictionary in Unity’s Inspector by leveraging Custom Property Drawers and Lists. This approach not only makes debugging and data management easier but also significantly improves the efficiency of your workflow by allowing real-time editing within the Unity Editor.

While this method adds some complexity to your codebase, the benefits of managing large datasets efficiently and debugging data visually far outweigh the initial setup cost. For developers working with a lot of dynamic data, using Dictionaries and exposing them in the inspector is a highly useful tool in your game development arsenal.

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