Insert Additional data into Lua table at index

Question

I have a table called "inventory", initialized like so:

inventory = {}

inventory[1] = { qty = 0 }

I want to add more data to this table, at the index 1, eg:

val = { id = "example" }

inventory[1] = inventory[1], val

Is there a way I can do this while preserving the data that is already in this table at this index?

The final result should be something like:

inventory[1] = { qty = 0, id = "example" }

But if I try to print the id after trying this code I get:

print(inventory[1].id) == Nil

Possible duplicate of [Lua - merge tables?](https://stackoverflow.com/questions/1283388/lua-merge-tables) — J. Titus, Mar 13 '18 at 17:33

score 2 · Answer 1 · answered Mar 13 '18 at 16:55

2

inventory[1].id = "example"

or

inventory[1]["id"] = "example"

or

this other SO answer with first_table being inventory[1] and second_table being val.

FWIW, you'd need 2 variables on the left side of the expression for inventory[1] = inventory[1], val to work: a, b = x, y.

answered Mar 13 '18 at 16:55

J. Titus

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Thanks for the answer! Is there a way to do it without having to say specifically inventory[1].id? The data in val = { id = "example" } may not actually be called id, and may have more than one entry with different names! – Aaranihlus Mar 13 '18 at 17:01
That would be where the other SO answer comes in. That answer contains code to loop through the `val` table and apply key value pairs regardless of the key names. – J. Titus Mar 13 '18 at 17:32

score 0 · Answer 2 · edited Mar 14 '18 at 04:12

0

You need to take the first key in the table and use it:

local inventory = {}
inventory[1] = { qty = 0 }
local val = { id = "example" }

-- 

local KeyName = next(val)

inventory[1][KeyName] = val[KeyName]

print(inventory[1][KeyName]) 
-- or 
print(inventory[1].id)

edited Mar 14 '18 at 04:12

cyclaminist

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answered Mar 13 '18 at 17:31

Mike V.

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Insert Additional data into Lua table at index

2 Answers2