# Rad Model

> Guide for the RAD (Rapid Application Development) model including defattr, entity definitions, identities, and test builder patterns. Use when working with the data model, creating entities, or understanding database schema. Use when this capability is needed.

- Skill: `tomevault-io/rad-model` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/rad-model`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/rad-model/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/rad-model

---


# RAD Model

See also @ai/clojure-library-source-and-documentation.md in this project.

Our project defines a Datomic database (along with virtual attributes) via a Fulcro RAD attribute model. The
attribute options are defined in the namespace com.fulcrologic.rad.attributes-options. Our model is defined in the
source folder @src/main/myapp/model_rad, with the model.cljc file being the join point for everything.

Each entity in our database model has a model file (e.g. src/main/myapp/model_rad/invoice.cljc), though
entity attributes are actually grouped around an "identity" attribute (i.e. any defattr with `ao/identity?`
set to true.)

The grouping is done with `ao/identities`, which is a set of id attributes whose entities CAN include that
attribute. For example `ao/identities #{:product/id :invoice/id}` would be that the attribute could
appear on products or invoices.

A `defattr` MAY have an optional docstring just after the symbol (just like `def`). So the signature is
`(defattr sym docstring? database-keyword type options-map)`. The `type` is database specific, but most common
types like :int, :string, :keyword, and :ref are supported by Datomic.

The :ref type indicates that the attribute points to one (or many if the ao/cardinality is set to :many) entity. The
value of `ao/target` or `ao/targets` will specify id attributes of the target entities of the reference.

From this you can deduce a lot about the data model, and in fact namespaces like `myapp.lib.rad.introspection` do
just that.

The RAD model is used to generate many things: database schema, pathom resolvers, validations (malli schemas),
reports (see defsc-report) forms (defsc-form), import/export formats (csv, excel, etc.).

The legacy code has "builders" for making instances of objects for tests. In the newer code, we prefer a
pattern where, in the RAD model file, we add a function called `new-MODELNAME`, e.g. `new-product`. Such
functions should look like this:

```
(defn new-product
  "Create a product. The name will be the sku and temporary ID of the product. "
  [sku & {:as addl-attrs}]
  (merge
    {:db/id                      sku
     :product/id                 (new-uuid)
     :product/sku                sku
     :product/description        sku
     :product/inventory-tracked? false}
    addl-attrs))
```

Where the bare minimum arguments for a usable entity are included, and the user can specify named args to
override/fill in things that we give defaults for. Note that Datomic allows us to use strings as a :db/id, and
those will be unified among entities on a single transaction. The :tempids of the datomic result will then
include those strings as keys to the native :db/id of the created entities.
This allows us to quickly build things for tests:

```
(let [c    (new-company "Acme") ; sets :db/id to "Acme"
      ;; assigns a alt description and relates the new product to the company
      p    (new-product "sku-100" :product/company "Acme" :product/description "My Product") 
      conn (test-conn)
      {{:strs [Acme sku-100]} :tempids} (d/transact conn {:tx-data [p c]})]
  ...)
```

You should never change an existing "errant" builder function, since they are widely used in tests.

---
> Converted and distributed by [TomeVault](https://tomevault.io/claim/saskenuba) — claim your Tome and manage your conversions.
<!-- tomevault:4.0:skill_md:2026-04-13 -->