CODEWITHSUNDEEP
erlanglogic
user3550934
user3550934

Reputation: 11

how to generate list of records using list of lists data in erlang

I have list of lists like ItemListData = [[1,"ABC","DEF",30],[2,"AXN","FOO",23],[3,"BDE","FO1",21],..] and I would like to form list of records using record Item{ItemNo, Name, Description, quantity}. Items list length would be varying. What would be the best way to create new list of records using ItemListData.

Upvotes: 1

Views: 89

Answers (4)

Ed'ka
Ed'ka

Reputation: 7158

Just use list_to_tuple:

rd(item, {num, name, descr, qty}),    
Ls = [[1,"ABC","DEF",30],[2,"AXN","FOO",23],[3,"BDE","FO1",21]],
[list_to_tuple([item|L]) || L <- Ls].

Upvotes: 0

BlackMamba
BlackMamba

Reputation: 10252

You just need this:

rd(item, {num, name, descr, qty}).
L = [[1,"ABC","DEF",30],[2,"AXN","FOO",23],[3,"BDE","FO1",21]].
lists:map(fun([No, Name, Des, Qty]) -> #item{num = No, name=Name, descr=Des, qty=Qty} end, L).

Upvotes: 0

fenollp
fenollp

Reputation: 2496

@graymalkin's answer involves a lot of copying through the use of the ++ binary operator. One should prefer list comprehensions here:

make_records(Records) ->
    [#item{'#'=No, name=Name, descr=Descr, qty=Qty}
    || [No,Name,Descr,Qty] <- Records].

Edit: Use this function thusly: (in the shell)

1> rd(item, {'#', name, descr, qty}).
2> ItemListData = [[1,"ABC","DEF",30],[2,"AXN","FOO",23],[3,"BDE","FO1",21]].
3> some_module:make_records(ItemListData).

Upvotes: 1

graymalkin
graymalkin

Reputation: 51

Something like this would do...

make_records([], Records) -> Records; make_records([[No,Name,Desc,Qty]|Xs], Records) -> make_records(Xs, Records ++ Item{itemNo = No, name = Name, desc = Desc, qty = Qty}).

Upvotes: 0

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