How to display a private field in the Unity Inspector as read-only

Question

I’m working on a Unity project and I have a private field in one of my scripts that I’d like to display in the Unity Inspector. However, I want to ensure that this field is read-only and cannot be modified from the Inspector, just like private fields appear in Debug mode?

Below is a picture showing a private field in Debug mode.

It can be a package, a custom editor, or anything else.

Answer 1

One way to solve it is creating a custom PropertyAttributes/Drawer, like this one:

PropertyAttribute:

using UnityEngine;

public class DisplayWithoutEdit : PropertyAttribute
{
}

PropertyDrawer:

using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(DisplayWithoutEdit))]
public class DisplayWithoutEditDrawer : PropertyDrawer
{
    public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
    {
        return EditorGUI.GetPropertyHeight(property, label, true);
    }

    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        GUI.enabled = false;
        EditorGUI.PropertyField(position, property, label, true);
        GUI.enabled = true;
    }
}

Use it like:

[SerializeField, DisplayWithoutEdit] private int variable = 2;