Elixir way to conditionally update a map

It also warns me of this. So confusing :s

Note variables defined inside case, cond, fn, if and similar do not leak. If you want to conditionally override an existing variable “data”, you will have to explicitly return the variable. For example:

So you want to update the body key value pair to the data map when the body key exists?

I just want to add the :body key/value pair into the json blob if the body variable isnt nil. Im’ sending a message, and body is optional, but I can’t send NULL in the json or it literally puts a blank space.

You can use Map.has_key?(data, :body) with a case statement. A more Elixir way might be to pattern match on the presence or absence of the map.

def process(%{body: _} = data), do: data
def process(%{} = data), do: %{data | body: nil}

Is there a way that doesnt require creating methods to do it? I suppose I could do that, i feel like my module will get cluttered very fast if i have so many methods to do something like that

How would the case statement look?

This has got to be the most frustrating day coding since i learned ruby like 10 years ago JESUS CHRIST.

I have spent 3 hours just trying to get a stupid map to update

Here is what i had so far

data =
  Enum.reject(
    %{
      requireInteraction: true,
      title: title,
      body: body,
      icon: icon,
      click_action: click_action
    },
    &(!elem(&1, 1))
  )

damnit it converts it to a list… this gives me so much of a headache. i have never been stuck on such easy stuff in so long, this is by far the hardest coding day in LONG TIME

Imo this is a elixir way as well to do it:

data = %{
  requireInteraction: true,
  title: title,
  icon: icon,
  click_action: click_action
}

data =
    if body do
      Map.put(data, :body, body)
    else
      data
    end

personally I’d prefer to create more functions like MrDoops pointed out, you can do anonymous functions as well

Ok.. I guess skip all my preconceptions and just use the method way. The only problem is it doesnt remove the key it only sets it to NULL (I need to remove the key).

I don’t like to have two variables with same name in scope. For me such code is less readable.

If you have only one variable like that then use if or && with || instead like:

data = %{…}
updated_data = if body, do: Map.put(data, :body, body), else: data
# or
updated_data = body && Map.put(data, :body, body) || data

In case you need to do it multiple times then I recommend to do something like:

data = %{…}
data2 = %{example: 5, body: body, sample: 10}
Enum.reduce(data2, data, fn {key, value}, acc -> value && Map.put(acc, key, value) || acc)

This is equivalent for maps:

:maps.filter(fn _key, value -> not is_nil(value) end, data)