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Model specification

Source: vignettes/model-specification.Rmd
model-specification.Rmd

See Authoring model definitions to create your first model.

Field types and constraints

Every field declares a type:

  • string: text.
  • email: text matching ^[^\s@]+@[^\s@]+\.[^\s@]+$; mailbox existence is not checked.
  • integer: a finite number without a fractional part.
  • number: a finite number.
  • boolean: true or false.
  • latitude: a finite number in decimal degrees, from -90 to 90 inclusive.
  • longitude: a finite number in decimal degrees, from -180 to 180 inclusive.
  • date: a valid date string in YYYY-MM-DD format.
  • datetime: a valid UTC datetime string in YYYY-MM-DDTHH:MM:SSZ format.

Coordinate types already include their geographic bounds. Missing values are governed by requiredness.

Optional constraints are:

  • mandatory: requires a filled value; omitted means false.
  • required_field: requires a value when the named field on the same sheet is filled.
  • enum: a nonempty list of distinct, non-null values matching the type, bounds and pattern.
  • minimum, maximum: inclusive numeric bounds; integer bounds must be whole numbers.
  • maximum_field: the value must not exceed the named numeric field on the same sheet; compare only valid, present values.
  • pattern: a PCRE regular expression for string, email, date or datetime fields.
  • sequence: consecutive integer numbering in worksheet order, grouped by same-sheet fields. Declare sequence: {start: 1, group_by: [trip_id, catch_id]} on an integer or string table field.
  • unique: requires distinct values within a repeated table field.
  • code_list: an ID declared under references.code_lists for a string or email field.
  • registry: an ID declared under references.registries for a string or email field.

Enums are constraints, not a separate type. Quote numeric-looking string codes: enum: ["01", "02"].

For conditional fields, required_field: length makes the unit required when length is filled, including zero.

In tables, this applies within the same row. A field cannot depend on itself; mutual dependencies are allowed.

The condition still permits a unit when length is empty.

Both bindings default to error severity. Use code_list: {id: observers, severity: warning} for a warning.

For registries, use registry: {id: contacts, column: email, severity: warning}. Matching defaults to exact; name requires a string field. Registry aliases belong to the supplied registry snapshot, not the form field.

For example, declare the registry under references, then bind a string field:

references:
  registries: [contacts]

The field declaration is:

contact_email: {location: C4, type: email, registry: {id: contacts, column: email, severity: warning}}

The model declares IDs and matching policy, but carries no reference data. Callers supply code-list and registry snapshots when validating submitted data.

See ?form_fields for the effective field properties returned by accessors.

Workbook layouts

sheets is an ordered mapping of worksheet names. Every declared sheet is required; names are unique ignoring case.

Each sheet has a layout, an optional primary_key, and fields, keyed by local field name.

  • kind: cells: requires column_count. Each field needs a unique uppercase A1 location, such as E3.
  • kind: table: requires start_row. Field order defines columns; omit field location and layout column_count.

Table column counts are derived from the fields. An explicit column_count must match that count.

Rows before start_row are preamble.

An optional row_count declares the exact physical row count. Fixed locations must fit declared dimensions.

Coordinates are one-based. An empty sheet can declare fields: {}; an empty table derives a column count of zero.

Primary keys

A table can declare one field or an ordered combination of fields as its primary key:

primary_key: [station, observation_id]

Every component must be filled; the combination identifies one row within that sheet of a submitted form.

Individual components may repeat in a composite key. Field-level unique still means individual uniqueness.

Use local field names. Keys must be nonempty, contain no repeated fields, and reference declared table fields.

Omit primary_key when no key is defined. Fixed-cell sheets cannot declare a primary key.

form_sheets() and form_definition() retain the declaration without changing field constraints.

This package checks key definitions. Checking submitted key values belongs to the validation package.

YAML conventions

Use one UTF-8 document. Tags, anchors, aliases, merges, directives and document markers are unsupported.

Mapping keys must be unique strings. Unknown properties are errors.

Quote versions and codes, especially leading-zero codes such as "01".

Use true and false for booleans. Quote text codes such as "yes", "no", "on" and "off".

Empty YAML values, null and ~ mean null; "" means an empty string. Omit unused optional properties.

Identifiers start with an ASCII letter, followed by letters, digits, dots, underscores or hyphens.

Full field IDs combine the sheet and field names: <sheet>.<field>.

Write field properties in this order: mandatory when true, location for cells, type, required_field, then constraints.

schema_version: "1.0.0" selects the package contract. form.version independently identifies your model version.

Change form.version when the model meaning changes. New schema properties require a supported contract version.

Definition checks

Load a file with read_form_model() to check its structure and consistency.

Use check_form_model() on a definition list to get diagnostics with source, property path and message.

Consistency checks run only after structure passes. Submitted-data validation belongs to form.validation.