DTOs

The DTO language can generate a polymorphic view or input from an inheritance root. Common properties are declared normally and type-specific properties are placed in #types branches.

Client.dto

export com.example.model.Client
    -> package com.example.dto

ClientView {
    id
    name
    #types {
        Organization {
            taxCode
        }
        Person {
            firstName
            lastName
        }
    }
}

The generated DTO metadata creates a root fetcher with matching forType branches. Converting an entity to the DTO selects the generated branch according to the actual entity type.

Exhaustive and Default Branches

Use #exhaustive when every instantiable entity type must have an explicit branch:

ClientView {
    id
    #types {
        #exhaustive
        Organization {
            taxCode
        }
        Person {
            firstName
        }
    }
}

Compilation fails if a concrete branch is missing. Without #exhaustive, types without an explicit branch use an implicit catch-all branch containing the common properties.

Declare default to customize that catch-all branch or give it a generated class name:

ClientView {
    id
    #types {
        default class Other {
            name
        }
        Organization class Company {
            taxCode
        }
    }
}

An explicit branch can also use class SomeName to customize its generated Java/Kotlin name.

Polymorphic Inputs

The same syntax is supported by input DTOs:

input ClientInput {
    id
    name
    #types {
        #exhaustive
        Organization {
            taxCode
        }
        Person {
            firstName
            lastName
        }
    }
}

Generated input branches implement Input<Client> and convert to the matching derived entity type, so they can be passed directly to save commands.

For JSON polymorphism, Jimmer generates Jackson type metadata using the entity discriminator property and each branch's discriminator value. Standard @JsonTypeInfo, @JsonTypeName, and @JsonSubTypes annotations in the DTO file can override that metadata when the external API uses different type tags.

The discriminator property may also be selected as an ordinary DTO field, renamed with as, or used by a default input branch to route conversion to a known entity type.

For the general DTO language syntax, see DTO Language.