![]() ![]() ![]() # Annotate the action we tried to perform so the UI shows errorsĬhangeset = % _all "profiles", Registration.to_profile(registration) _all "accounts", Registration.to_account(registration) # Get the modified registration struct out of the changeset Now that the registration changes are mapped and validated, we can check if the resulting changeset is valid and act accordingly: if changeset.valid? do With the schema in hand, we can use Ecto changesets and validations to process the data: fields = We used embedded_schema because it is not our intent to persist it anywhere. For such, let’s define a schema named Registration that will take care of casting and validating the form data exclusively, mapping directly to the UI fields: defmodule Registration do ![]() The first will cast and validate the external data with its own structure which you then transform and write to the database. One alternative solution is to break the “Database Ecto schema Forms / API” mapping in two parts. If the Profile schema is used for both reading and writing data, it may end-up in an awkward place where it is not useful for any, as it contains fields that map just to one or the other operation. It is not hard to see how we are polluting our Profile schema with UI requirements by adding fields such first_name and last_name. One of such schemas would be: defmodule Profile doįield :first_name, :string, virtual: true One approach would be to have two schemas, Account and Profile, with virtual fields such as first_name and last_name, and use associations along side nested forms to tie the schemas to your UI. Given the requirements above, how would we implement the Sign Up feature in the backend? Furthermore, you know it would be useful to break the “Sign Up” information across two tables, the “accounts” and “profiles” tables. Although your client is decided on presenting both fields, they are a UI concern, and you don’t want the UI to dictate the shape of your data. You know there are a couple problems with this approach.įirst of all, not everyone has a first and last name. Imagine you are working with a client that wants the “Sign Up” form to contain the fields “First name”, “Last name” along side “E-mail” and other information. It is important to understand how the schema is sitting between your database and your API because in many situations it is better to break this mapping in two. Where: a.start_at > type(^start_at, Ecto.DateTime) and It is often simpler to write a query that returns only the data you need, without taking schemas into account: import Ecto.Query If you are writing a reporting view, it may be counter-productive to think how your existing application schemas relate to the report being generated. insert_all was the last piece of the puzzle. Schemaless queriesĮcto 2.0 allows read, create, update and delete operations to be done without a schema. With schemaless queries, we get direct access to all underlying database operations, allowing us to perform both reads and writes operations without being coupled to a schema. While the benefits of schemas are known, we don’t talk as frequently about the downsides of schemas: which is exactly the coupling of the database representation to your application, leading developers to represent both reads and writes operations on top of the same structure. In the example above, the “votes” field was automatically cast from string to an integer based on its schema type. |> (params, )īy relying on the schema information, Ecto knows the shape of the data when it reads from the database and know how to manage changes. One possible benefit of using schemas is that you define the shape of the data once and you can use this shape to retrieve data from the database as well as coordinate changes happening on the data. Schemas are useful because they give shape to external data and enforce its types: defmodule Post do One important decision in this direction was the removal of Ecto.Model in favor of Ecto.Schema.Īt this point, it is worth asking: what are schemas?Įcto schemas are used to map any data source into an Elixir struct. We want developers to think of Ecto as a tool instead of their domain layer. The trouble with schemasĬonceptually speaking, Ecto 2.0 is quite different from Ecto 1.0 as it moves to a more data-oriented approach. To understand more about these goals, let’s talk about Ecto schemas. insert_all allows developers to insert multiple entries at once into a repository: _all(Post, ,Īlthough insert_all is just a regular Elixir function, it plays an important role in Ecto 2.0 goals. One of the functions added to Ecto 2.0 is _all/3. Ecto’s insert_all and schemaless queries May 4, 2016 ![]()
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