form-codegen

Models + Forms: typed model.Definition → ormc → everything else

The ONE pattern (source of truth)

A model is authored as a typed model.Definition literal. The var name MUST end in Model — that is how ormc discovers it:

import (
    "github.com/tinywasm/form/input"
    "github.com/tinywasm/model"
)

var LoginDataModel = model.Definition{
    Name: "login_data",
    Fields: model.Fields{
        {Name: "email",    Type: model.FieldText, NotNull: true, Widget: input.Email()},
        {Name: "password", Type: model.FieldText, NotNull: true, Widget: input.Password()},
    },
}

var ProductModel = model.Definition{
    Name: "product",
    Fields: model.Fields{
        {Name: "id",    Type: model.FieldInt,  DB: &model.FieldDB{PK: true, AutoInc: true}},
        {Name: "name",  Type: model.FieldText, NotNull: true, Permitted: model.Permitted{Minimum: 2}, Widget: input.Text()},
        {Name: "price", Type: model.FieldFloat, Widget: input.Number()},
    },
}

• DB tables: fields carry DB: &model.FieldDB{...} metadata.
• Form-only DTOs (login, filters, …): NO DB metadata — same pattern, just no table.
• UI binding: Widget: input.Email() etc. (typed expression from tinywasm/form/input). A field without Widget gets NO input in forms.

Then generate:

go generate ./...   # runs ormc (//go:generate ormc); install:
go install github.com/tinywasm/orm/cmd/ormc@latest

ormc parses the Definition literal (including the Widget: expressions) and generates the concrete Go struct plus ModelName(), Schema(), Pointers(), Validate(), EncodeFields()/DecodeFields() (typed codec) and the *List type, into the generated *_orm.go file. Never edit generated files — they are overwritten on every run.

FORBIDDEN (these are the bugs this skill exists to prevent)

• ❌ Struct tags as source of truth (input:"email", db:"pk" on hand-written structs). The Definition literal is typed; tags are the old, removed pattern.
• ❌ Hand-writing the struct or any generated method (Schema, Pointers, ModelName, Validate, Encode/DecodeFields).
• ❌ Stdlib encoding/json anywhere. Only tinywasm/json, which works exclusively through the generated typed codec — a hand-written DTO without generated Encode/DecodeFields cannot travel.
• ❌ form.RegisterInput as a fix for empty forms. form.New binds inputs ONLY via Field.Widget from the schema — there is no name matching. If a form renders without fields, the Definition is missing Widget: entries → fix the Definition and regenerate; never patch at the consumer.

Library roles

| Library | Responsibility | Knows about | |---|---|---| | model | Definition, Field, Fielder, Widget iface, Permitted, ValidateFields, typed codec contracts | nothing else | | orm / ormc | DB mapping + THE code generator (Definition → struct + methods) | model | | form | form.New(parentID, &Generated{}) — schema-driven form; SSR + reactive render | model, dom, form/input | | form/input | Concrete widgets with validation (Email, Password, Phone, Text, Number, Checkbox, Textarea, …) | model | | json | Zero-reflection codec over generated Encode/DecodeFields | model | | dom | Pure HTML layout elements + signals. NO form functions (no Input(), Form(), …) | — |

Validation flow (same code front + back)

model.ValidateFields(action, m)
  → per field: NotNull → Widget.Validate (semantic) → Permitted (chars/length)

Runs identically in WASM (form.Validate()) and on the server (after decode, before persistence).

How to instruct an agent in a PLAN.md

1. Write the model.Definition literal(s) — var name ending in Model, every form-visible field with an explicit Widget:.
2. Delete any hand-written struct the Definition replaces (ormc generates it; names would collide).
3. Run go generate ./... (ormc). Verify the generated schema carries the widgets and codecs.
4. Regression test: form.New(id, &Generated{}) yields exactly the expected number of inputs — catches a future regeneration that loses widgets.

Custom inputs

A project may define custom widgets (same model.Widget contract) and use them in its Definitions like any input.Xxx(). They live with the consumer; stdlib widgets live in tinywasm/form/input.