Unity 5 Inventory system not working - unity3d

Question

Hello programmers all around the world. I have made myself an inventory system for my game. Only problem is that when I click on item and then drag it to and empty slot it doesn't move and I kinda don't see the error which I am having and I have tried to debug it but without success any help? Here is the code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
public class Inventory : MonoBehaviour {
private RectTransform inventoryRect;
private float inventoryWidth;
private float inventoryHeight;
public int slots;
public int rows;
public float slotPaddingLeft;
public float slotPaddingTop;
public float slotSize;
public GameObject slotPrefab;
private static Slot from;
private static Slot to;
private List<GameObject> allslots;
public GameObject iconPrefab;
private static GameObject hoverObject;
private static int emptySlots;
public Canvas canvas;
private float hoverYOffset;
private bool isPressed;
public EventSystem eventSystem;
public static int EmptySlots{
get{ return emptySlots;}
set{ emptySlots = value;}
}
// Use this for initialization
void Start () {
CreateLayout ();
canvas.enabled = false;
isPressed = false;
}
// Update is called once per frame
void Update () {
if (Input.GetKeyDown (KeyCode.I)) {
if (Input.GetKeyDown (KeyCode.I)) {
canvas.enabled = false;
}
canvas.enabled = true;
}
if (Input.GetMouseButtonUp (0)) {
if (!eventSystem.IsPointerOverGameObject (-1) && from != null) {
from.GetComponent<Image> ().color = Color.white;
from.ClearSlot ();
Destroy (GameObject.Find ("Hover"));
to = null;
from = null;
hoverObject = null;
}
}
if (hoverObject != null) {
Vector2 position;
RectTransformUtility.ScreenPointToLocalPointInRectangle (canvas.transform as RectTransform, Input.mousePosition, canvas.worldCamera, out position);
position.Set (position.x, position.y - hoverYOffset);
hoverObject.transform.position = canvas.transform.TransformPoint (position);
}
}
private void CreateLayout(){
allslots = new List<GameObject> ();
hoverYOffset = slotSize * 0.01f;
emptySlots = slots;
inventoryWidth = (slots / rows) * (slotSize + slotPaddingLeft) + slotPaddingLeft;
inventoryHeight = rows * (slotSize + slotPaddingTop) + slotPaddingTop;
inventoryRect = GetComponent<RectTransform> ();
inventoryRect.SetSizeWithCurrentAnchors (RectTransform.Axis.Horizontal, inventoryWidth);
inventoryRect.SetSizeWithCurrentAnchors (RectTransform.Axis.Vertical, inventoryHeight);
int colums = slots / rows;
for (int y = 0; y < rows; y++) {
for (int x = 0; x < colums; x++) {
GameObject newSlot = (GameObject)Instantiate (slotPrefab);
RectTransform slotRect = newSlot.GetComponent<RectTransform> ();
newSlot.name = "Slot";
newSlot.transform.SetParent (this.transform.parent);
slotRect.localPosition = inventoryRect.localPosition + new Vector3 (slotPaddingLeft * (x + 1) + (slotSize * x), -slotPaddingTop * (y + 1) - (slotSize * y));
slotRect.SetSizeWithCurrentAnchors (RectTransform.Axis.Horizontal, slotSize);
slotRect.SetSizeWithCurrentAnchors (RectTransform.Axis.Vertical, slotSize);
allslots.Add (newSlot);
}
}
}
public bool AddItem(Item item){
if (item.maxSize == 1) {
PlaceEmpty (item);
return true;
}
else {
foreach (GameObject slot in allslots) {
Slot temporary = slot.GetComponent<Slot> ();
if (!temporary.IsEmpty) {
if (temporary.CurrentItem.type == item.type && temporary.IsAvailable) {
temporary.AddItem (item);
return true;
}
}
}
if (emptySlots > 0) {
PlaceEmpty (item);
}
}
return false;
}
private bool PlaceEmpty(Item item){
if (emptySlots > 0) {
foreach (GameObject slot in allslots) {
Slot temporary = slot.GetComponent<Slot> ();
if (temporary.IsEmpty) {
temporary.AddItem (item);
emptySlots--;
return true;
}
}
}
return false;
}
public void MoveItem(GameObject clicked){
if (from == null) {
if (!clicked.GetComponent<Slot> ().IsEmpty) {
from = clicked.GetComponent<Slot> ();
from.GetComponent<Image> ().color = Color.gray;
hoverObject = (GameObject)Instantiate (iconPrefab);
hoverObject.GetComponent<Image> ().sprite = clicked.GetComponent<Image> ().sprite;
hoverObject.name = "Hover";
RectTransform hoverTransform = hoverObject.GetComponent<RectTransform> ();
RectTransform clickedTransform = clicked.GetComponent<RectTransform> ();
hoverTransform.SetSizeWithCurrentAnchors (RectTransform.Axis.Horizontal, clickedTransform.sizeDelta.x);
hoverTransform.SetSizeWithCurrentAnchors (RectTransform.Axis.Vertical, clickedTransform.sizeDelta.y);
hoverObject.transform.SetParent (GameObject.Find ("Canvas").transform, true);
hoverObject.transform.localScale = from.gameObject.transform.localScale;
}
}
else if (to = null) {
to = clicked.GetComponent<Slot> ();
Destroy (GameObject.Find ("Hover"));
}
if (to != null && from != null) {
Stack<Item> tmpTo = new Stack<Item> (to.Items);
to.AddItems (from.Items);
if (tmpTo.Count == 0) {
from.ClearSlot ();
}
else {
from.AddItems (tmpTo);
}
from.GetComponent<Image> ().color = Color.white;
to = null;
from = null;
hoverObject = null;
}
}
}
The method which is causing the problem is the MoveItem() sadly it is not a nullreference or nullpointer and I simply am out of ideas been strugling with it for a couple of days... Any advice on how to fix this would be helpfull and much welcomed indeed. Thanks in advance!

Answer 1

I haven't taken a long look at your code but right away I saw this issue:
else if (to = null) {
to = clicked.GetComponent<Slot> ();
Destroy (GameObject.Find ("Hover"));
}
This is causing the end location to be set to null. To fix this, change to double equals like so:
else if (to == null) {
to = clicked.GetComponent<Slot> ();
Destroy (GameObject.Find ("Hover"));
}
If this does not solve your problem, let me know and I'll look at your code harder.