#ELIXIR ECTO CAST CODE#

Even though, as mentioned in the documentation, it's typically used for data from a persistent source like a database. Such structs do not contain a _meta_ field, as they are never persisted.įrom the above documentation itself, using `Ecto.Schema` to map external JSON data is an acceptable approach, and it's meant to be used in that way. For example, you can use such schemas to receive data from a command line interface and validate it, without ever persisting it elsewhere. On the other hand, embedded_schema/1 is used for defining schemas that are embedded in other schemas or only exist in-memory. Structs defined with schema/2 also contain a _meta_ field with metadata holding the status of the struct, for example, if it has been built, loaded or deleted. For this reason, the first argument of schema/2 is the source (table) name. Schema/2 is typically used to map data from a persisted source, usually a database table, into Elixir structs and vice-versa. The definition of the schema is possible through two main APIs: schema/2 and embedded_schema/1. To quote from the introduction section of `Ecto.Schema` (emphasis added by me): An Ecto schema is used to map any data source into an Elixir struct.

#ELIXIR ECTO CAST CODE#

First, isn't `Ecto.Schema` and `Ecto.Changeset` typically used for mapping and validating data from a persistent source like a database? Second, isn't this a bit overkill as it adds additional dependency to the API client module? I've been code reading quite a number of Elixir project/module for the past few months and never comes across any third parties Elixir API client which applies such style.įor the first question, it seemed that I don't read the `Ecto.Schema` and `Ecto.Changeset` carefully. When I first read about such usage, two things came to mind. While doing that, we can also use `Echo.Changeset` to filter, cast, and validate the fields of external JSON data. If we want to refine it further, we can use `Ecto.Schema` to map external JSON data to Elixir struct. If we want to go a step further, we can create an Elixir struct (named Elixir Map) through `defstruct/1`. When writing a third party API client, typically we just parse the JSON response as a generic Elixir Map. As I've worked mostly in the third party API client, it never occurred to me that we can actually use `Ecto.Schema` to construct and wrap the external JSON struct. As mentioned in my weekly review, one of the profound Elixir tip that I've been told was to use `Ecto.Schema` to map external JSON struct from third party API endpoint.

Elixir ecto cast