(time_manager 0.1.0) lib/time_manager_web/controllers/workingtime_controller.ex:1: /2 (time_manager 0.1.0) lib/time_manager_web/controllers/workingtime_controller.ex:16: /2 (time_manager 0.1.0) lib/time_manager/workingtimes.ex:63: _workingtime/1 (time_manager 0.1.0) lib/time_manager/workingtimes/workingtime.ex:16: /2 |> validate_required()Īnd here is my create function in the controller: def create(conn, workingtime_params) do This is the POST request i'm trying to do: In this case, you're most likely using conn somewhere in your template, and it's trying to run Dict.fetch(changeset, :conn), which delegates to (changeset, :conn) as changeset is a struct, and ends up calling (changeset, :conn). Most of the time this isn't an issue, but it does lead to a little inflexibility (and this is always a trade off).I've been stuck with a casting error with naivedatetime. I will cover this in the next article.įor myself, when I moved from Rails to Elixir, it made me realise how much was going on behind the scenes that I took for granted. These data contexts can be based off macros to give an inheritance like functionality. the CRUD operations) and then put any extra functionality into another context. In practice, you might want to have a Data context which deals solely with tying the schema to the database (e.g. you either have all the required fields at once, or the model is invalid). Thank you That’s what I was looking for (don’t worry, validating the. without inserting to the DB), you can use /1 but be careful: it’s gonna return a struct regardless if the changes was valid or not, so you’ll probably want to validate it explicitly first. In Rails, this is an all or nothing situation (e.g. When you want to turn changeset into struct (e.g. You might even have a multi phase scaffolding process which only requires some fields to be updated at a time (user sign up is one). What we mainly use it for is to allow us to easily have different changesets for different situations (e.g. The changeset is automatically defined for you in Rails. The functionality is separate from the data.Īnother thing that looks weird is having to define the changeset. If you dont have an else branch and the condition is false, the return value is nil.
In if statements, the last value of both its true and false branch is its return value. In Elixir, the last value in a block is its return value.
#ELIXIR ECTO CHANGESET SERIES#
Everything is a series of data transformations. Youre not returning the modified changesets properly in validaterequiredinclusionformat.
#ELIXIR ECTO CHANGESET CODE#
What I found in Phoenix and Elixir is that you can move great chunks of code around quite easily compared to Rails because there is no state on the models/structs. # PS this is also an example of destructuring which I will cover laterĭef full_name(%) doĪuthor_full_name = _name(author)Īdmin_full_name = _name(admin) #implement other data access methods as requiredĪlias One author has many articles, one article has many comments and a comment also has an author as well.Ĭlass Article cast(params, Context.Articles do I will probably do a follow up on this, but essentially using macros we created a pseudo inheritance pattern where all our data layer modules get default read and write actions (as well as return the data in tuples for error handling).Īnyways, an example is worth a thousand lines of text, so let's see how we would implement a basic blog data model in Rails vs Phoenix. In the project I am working on, we added another convention which was to have a contextual data layer which dealt with all the CRUD operations of our schema. If you want to transform the data on your struct, you would use a context module (basically a collection of functions which take the struct in one format and return it in another). Using the schema file, your "instance" is essentially a data structure (with no methods on it). You have a schema file (where you have to list out all the attributes and relationships). What happens in one file in Rails, happens in essentially two (or more). In fact we don't really have models (as Elixir is a functional paradigm). First of all, the database schema doesn't automatically map to the "model". Your instance of the model has all the methods built in. Let's define the schema and the changeset function for a post which may receive tags as a string: defmodule MyApp.Post do use Ecto.Schema schema 'posts' do field :title field :body manytomany :tags, MyApp.Tag. This file is also where you set your model relationships (e.g. In putassoc/4, we give Ecto structs or changesets instead of parameters, giving us the ability to manipulate the data as we want. You have an Active Record model which maps to the database table, the schema of the model comes directly from the database schema and you place your model specific methods on the Active Record model. (The final argument of each is optional). Rails has a very well established Active Record pattern for dealing with the database. There are two ways of making an Ecto changeset.
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