Ash.Dsl.Entity (ash v1.47.8) View Source
Declares a DSL entity.
A dsl entity represents a dsl constructor who's resulting value is a struct. This lets the user create complex objects with arbitrary(mostly) validation rules.
The lifecycle of creating entities is complex, happening as Elixir is compiling
the modules in question. Some of the patterns around validating/transforming entities
have not yet solidified. If you aren't careful and don't follow the guidelines listed
here, you can have subtle and strange bugs during compilation. Anything not isolated to
simple value validations should be done in
An entity has a
target indicating which struct will ultimately be built. An entity
also has a
schema. This schema is used for documentation, and the options are validated
against it before continuing on with the DSL.
To create positional arguments to the builder, use
args. The values provided to
args need to be in the provided schema as well. They will be positional arguments
in the same order that they are provided in the
auto_set_fields will set the provided values into the produced struct (they do not need
to be included in the schema).
transform is a function that takes a created struct and can alter it. This happens immediately
after handling the DSL options, and can be useful for setting field values on a struct based on
other values in that struct. If you need things that aren't contained in that struct, use an
entities allows you to specify a keyword list of nested entities. Nested entities are stored
on the struct in the corresponding key, and are used in the same way entities are otherwise.
For a full example, see