Concepts

Dynamic Model distinguishes two kinds of entities:

Dynamic attributes can be added to both static and dynamic entities. This means you can enrich existing application entities with new attributes and, independently, introduce completely new entities that exist only in the runtime model.

The dynamic model is a declarative description of enumerations, entities, attributes, and views. You edit it graphically in the admin UI: you create entities, add attributes with their types and constraints, define enumerations, and declare views and menu items.

Behind the scenes, the model is serialized as YAML. You normally work with the graphical editor and do not edit the YAML directly, but the YAML form is useful for review, export, and import. For the full list of elements, supported values, and defaults, see YAML Reference.

The model definition is stored in the database as a set of versioned configurations. Each apply saves a new version, and only one version is active at a time. Previous versions are kept, and you can see them in the model history. To return to an earlier model, copy its YAML from the history and apply it again.

On application startup, the framework can automatically apply the active version so that the running application reflects the latest deployed model. This behavior is controlled by the jmix.dynmodel.deploy-on-app-start property.

When you apply the model, the framework builds a new metadata generation from the model definition and publishes it atomically. Until the new generation is fully prepared, the running application keeps using the previous one, so a failed apply never exposes a partially applied model.

Destructive cleanup — such as dropping columns or tables that are no longer part of the model — is deferred until the previous generation is no longer used by in-flight work. This keeps running operations consistent while the model changes.

Already open views are not switched over automatically; they pick up the changes after a reload.

The framework also checks that nobody applied another model after you opened the model for editing. If someone did, your apply is refused, so that it does not silently discard the other changes. In this case, reload the model settings and repeat your changes.

Dynamic Model can work in an application cluster. When cluster support is enabled:

To enable cluster support:

The jmix.dynmodel.cluster.apply-lock-timeout-sec property sets when the lock left by a node that stopped during an apply expires. Set it to a value greater than the longest apply in your application.

Dynamic Model keeps the runtime data in dedicated database tables:

Each entity can specify a physical store through its store property; when omitted, the entity uses the main data store. References and collections are allowed only between entities that belong to the same physical store.

The table-name prefixes are configurable; see YAML Reference and Application Properties for the relevant settings.

Dynamic entities and dynamic attributes are shown in the views of the Data Tools add-on:

Dynamic Model supports the following databases: