godot invalid get index '-1'(on base 'array') during A.P.I

Question

I'm making an A.P.I. that displays dialogue, choices, sprites, audio etc. etc., i was able to do it after looking up this video on youtube but i keep getting this error invalid get '-1' (on base 'array') here's my code so you can see

    extends Control 

onready var bg_rect = get_node("Media_Sys/BG_Rect")
onready var char_sprite = get_node("Media_Sys/Sprite")
onready var text_box = get_node("Dialog_Sys/Dialog_Text")
onready var text_nam = get_node("Dialog_Sys/Label/Name")
onready var click = get_node("ClickManager")

var player = []

var lu = "Lu"
var ciel = "Ciel"

func _ready():
    click.request_ready()


func write(char_name_str, text_str=null):

    if text_str == null:

        text_str = char_name_str
        char_name_str = ""

    player.push_front({"type": "dialogue","name": char_name_str, "text": text_str})

func write_component():

    text_nam.clear()
    text_box.clear()
    text_nam.add_text(player[player.size() - 1]["name"])#the debugger says the problem is here
    text_box.add_text(player[player.size() - 1]["text"])#as well as here if you remove the first line.
    player.pop_back()

func _input(event):

    if event is InputEventMouseButton:

        write_component()

I have some people say that it's because i didn't define the size of the array, i have some people say that it's really weird that my code somehow set the player as an integer. I've check the array docs page for this and came up with nothing, I've changed some minor things in the code but it still churns out the same invalid error.

extends Node

onready var g = get_parent()

var lu = "Lu"
var ciel = "Ciel"


func _ready():
    g.write(lu, "hello")

One thing to note is that it does display the dialogue and name, i just get the error immediantly afterwards.

Your array "player" is empty when initialized, so when you try to access it in "Write_Component" with [player.size() - 1], if player.size() == 0, then you will get -1 as an array index. Write_Component is probably being called before Write. Try testing the size of player, e.g. " if player.size() > 0: add_text, pop_back else: #do_nothing — Nikolaj Baer, Dec 05 '18 at 18:51

score 1 · Accepted Answer · answered Dec 07 '18 at 01:37

You initialize the player variable to be an empty list. Then, in write_component you attempt to access this list with the calculated index [player.size() - 1]. The issue is that if player is empty, this ends up as [0-1] or [-1] as an index, which is not valid in GDScript. Your code assumes Write will be called first (and it may, some of the time) so that player is not empty by the time write_component is called.

The most immediate solution is to check if player.size() == 0 before attempting to access the last element.

func write_component():
    text_nam.clear()
    text_box.clear()
    if player.size() > 0:
        text_nam.add_text(player[player.size() - 1]["name"])
        text_box.add_text(player[player.size() - 1]["text"])        
        player.pop_back()

it works; but when try to transition next page of dialogue I get this error `Invalid get 'name'(on base 'dictionary')` what can i do to fix. also the error appears here. `text_nam.add_text(player[player.size() - 1]["name"])` — Lynn Len, Dec 07 '18 at 08:04
You are still trying to access the `player[]` array when it is empty. You need to review your logic to see what to do in the case that it is empty, or ensure that push something into `player` before accessing it. — Nikolaj Baer, Dec 07 '18 at 21:25

godot invalid get index '-1'(on base 'array') during A.P.I

1 Answers1