Constrains a string field's length

MaxLengthAttribute.cs

using UnityEngine;

#if UNITY_EDITOR
using UnityEditor;
#endif

public class MaxLengthAttribute : PropertyAttribute {
	public readonly uint Length;

	public MaxLengthAttribute(uint length) {
		Length = length;
	}
}

#if UNITY_EDITOR
[CustomPropertyDrawer(typeof(MaxLengthAttribute))]
public class MaxLengthAttributeEditor : PropertyDrawer {
	public override void OnGUI(Rect position, SerializedProperty property, GUIContent label) {
		if (property.propertyType == SerializedPropertyType.String) {
			MaxLengthAttribute attr = (MaxLengthAttribute)attribute;
				
			string value = property.stringValue;
			if (value.Length > attr.Length) {
				value = value.Substring(0, (int)attr.Length);
				property.stringValue = value;
				property.serializedObject.ApplyModifiedProperties();
			}
		}
			
		EditorGUI.PropertyField(position, property, label);
	}
}
#endif

Neato 👍