yeroc

yeroc

Case Statements for Error Handling in Ecto Changesets

Hi all! Going through the Ecto docs and trying to understand something-

Makes sense to me for their suggestion to use a case statement like

case Friends.Repo.insert(changeset) do
  {:ok, person} ->
    # do something with person
  {:error, changeset} ->
    # do something with changeset
end

for the error handling- just not quite sure how that’s implemented with the an existing Schema changeset like-

def changeset(person, params \\ %{}) do
  person
  |> Ecto.Changeset.cast(params, [:first_name, :last_name, :age])
  |> Ecto.Changeset.validate_required([:first_name, :last_name])
end

How exactly is this case statement wrapped in def changeset?

Additionally, in this case statement: what am I doing with the first {:ok, person} tuple? I understand with the {:error, changeset} tuple I can return something like-

traverse_errors(changeset, fn {msg, opts} ->
  Enum.reduce(opts, msg, fn {key, value}, acc ->
    String.replace(acc, "%{#{key}}", to_string(value))
  end)
end)

Thanks for any help :slight_smile:

Most Liked

dimitarvp

dimitarvp

The Changeset.* functions accept a changeset as a first argument and return an updated changeset. That enables the piping you’re seeing. At any point in the pipe you can inspect whether the changeset now has errors and if you want to do something about it.

Where Next?

Popular in Questions Top

jononomo
I am trying to figure out how Mix knows whether the environment is test, dev, or prod -- where is this set? Thanks.
New
vertexbuffer
Hello, can anybody help here..? I have a list of players and I what to delete an element, but every for loop the list is reverting to ori...
New
mgjohns61585
Could someone help me? I'm making my first elixir program, number guessing game. I can't figure out how to convert the user's guess from ...
New
makeitrein
Hey all, just started picking up Elixir last week and am writing a scraper as a learning project. Baby step #1 is extracting the number ...
New
ashish173
I am using Ecto timestamps with postgres, I can see the timestamps() use the :naive_dateime but for my use case I wanted to store the ti...
New
fireproofsocks
Forgive me if this is obvious, but how does one delete a database record WITHOUT selecting it first? https://hexdocs.pm/ecto/Ecto.Repo.h...
New
electic
Hi, I am new to Elixir. I am trying to use the DateTime component to insert a date into MySQL however the there seems to be no way to fo...
New
beno
I will often find my self writing things similar to: case some_value do nil -> something() "" -> something() _ -> someth...
New
skosch
To my knowledge, put_in, Map.update etc. all have the one limitation of not automatically creating intermediate keys when needed (for exa...
New
lanycrost
Hi everyone! I need implement if…else if…else condition from my elixir code, and anymore of this control flow structures not work proper...
New

Other popular topics Top

srinivasu
How to handle excepions in elixir? Suppose i have A, B, C ,D, E modules. and each module has get() function. A.get() method will call th...
New
albydarned
Hello all! I am typing this post from my new MacBook Pro with the M1 chip. I’m loving it so far, and will probably use it as my daily dr...
New
sergio_101
I am VERY much an elixir newbie. I have taken one elixir course and one phoenix course on Udemy. During that course, I saw the instructor...
New
grych
Hi folks, Few months ago I have announced the proof-of-concept of the library to manipulate the browsers DOM objects directly from Elixi...
639 49522 488
New
minhajuddin
I have seen a lot of code which picks the first element from a list using Enum.at(0) instead of List.first. Is there a reason why people ...
New
vonH
When I run the Plug and I recompile I wind up having to use Ctrl C to quit iex and start again. Witht the help of rlwrap I can use the cu...
New
ovidiubadita
Hey all, I discovered Elixir and I love it. I always wanted to learn a functional programming and I intended to go for Haskell, but afte...
New
chrisalley
ExUnit now has describe blocks which is a welcome addition coming from RSpec. In the docs, it states that nested hierarchies of describe ...
New
skosch
To my knowledge, put_in, Map.update etc. all have the one limitation of not automatically creating intermediate keys when needed (for exa...
New
romenigld
I am trying to run a deploy with docker and I successfully runned with this command: docker build -t romenigld/blog-prod . but when I t...
New

We're in Beta

About us Mission Statement