CODEWITHSUNDEEP
elixir
BeniaminoBaggins
BeniaminoBaggins

Reputation: 12443

Elixir - update a map which has string keys

How do I update a map which has string keys? I want to update the "brand" value.

My code (product is a map with "brand" key):

  brand = URI.decode(product["brand"])
  IO.inspect(brand, label: "uri decode")
  brand = elem(Poison.decode(brand), 1)
  IO.inspect(brand, label: "json decode")
  Map.put(product, "brand", brand)
  IO.inspect(product["brand"], label: "actual product brand")

outputs:

uri decode: "\"e&ggsssssaaqss\""
json decode: "e&ggsssssaaqss"
actual product brand: "%22e%26ggsssssaaqss%22"

It isn't updating product["brand"]

The actual product brand log should equal the json decode log if it gets updated.

What am I doing wrong?

Upvotes: 3

Views: 2176

Answers (2)

intentionally-left-nil
intentionally-left-nil

Reputation: 8284

A more terse syntax is the | operator

my_map = %{"a" => 1, "b" => 2}
%{my_map | "a" => 100}

or also you can use the put_in method

my_map = %{"a" => 1, "b" => 2}
put_in(my_map["a"], 100)

Upvotes: 2

timbuckley
timbuckley

Reputation: 76

If a map has string keys like so:

my_map = %{"a" => 1, "b" => 2}

You can create a new map with the changed key like this:

my_new_map = Map.put(my_map, "a", 100)

Or you can rebind the existing my_map variable with the updated map like so:

my_map = Map.put(my_map, "a", 100)

Upvotes: 4

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