Model CSV plugin

Adds an import CSV { … } block to the model language, so a model can take its objects from .csv files instead of listing them one by one. A spreadsheet of two hundred tasks becomes a model without two hundred hand-written objects.

At a glance

Plugin id	model-csv-service
Display name	Model CSV
Description	Language support for the CSV import contribution to the model language
Default URL	/plugin/model-csv
Source	app/packages/service-model-csv, app/packages/language-model-csv
Depends on	The Model and Metamodel plugins; the data files are usually CSV files

Only started by the development compose file

infra/docker-compose-dev.yaml builds this service and lists it in DEFAULT_PLUGIN_URLS. docker-compose.yaml and docker-compose-prod.yaml do not, so a production deployment has to add the service and register /plugin/model-csv itself.

Languages contributed

Language id	Name	Extension	Textual editor	Graphical editor	Generated
model-csv	Model CSV	—	❌	❌	✅

The model-csv language

A generated language with no file extension and no editor, following the same pattern as the config contribution plugins: it exists so the import block can be parsed as a language in its own right when the model service asks for the imported data to be computed.

Contribution plugins contributed

Target language	What it adds
model	The import CSV { … } block

Contribution plugin id	model-csv
Short name	csv
Additional keywords	import, CSV, from
Exported types	none

The import block

using "./tasks.mm"

import CSV {
    Task from "./tasks.csv"
    Employee from "./employees.csv"
}

Each entry maps one metamodel class to one CSV file. The class is a cross-reference into the metamodel named by using, so it is completed and validated in the editor like any other class name.

The same class may be imported from several files; the rows are appended.

How rows become objects

The rules below are applied by the plugin's request handler when the model service computes the model's data.

One row, one object. The header row names properties of the class; each following row becomes one object. Objects are named <Class>_<n>, numbered from zero across all files importing that class.

Values are converted to the declared type. A cell is read according to the property's type in the metamodel:

Property type	Cell
int, long	Parsed as an integer; a value that does not parse is kept as text
float, double	Parsed as a decimal; a value that does not parse is kept as text
boolean	true (case-insensitive) is true, everything else is false
enum	The cell is the entry name, e.g. BLUE
Everything else	Text

An empty cell becomes null.

References use the _id column. A reference column holds the _id value of the target row, and several targets are separated by ;:

_id,name,assignee
t1,Design,e1
t2,Build,e1;e2

_id is only a lookup key for the import — it does not become a property of the object.

Problems are warnings, not errors. The import never fails, it records what it could not do:

Situation	Result
Class not in the metamodel	The entry is skipped
File with only a header	The entry is skipped
Column matching no property	The column is ignored
Row shorter than the header	Missing cells treated as blank
Row longer than the header	Extra cells ignored
Reference to an unknown _id	The link is dropped

The warnings travel back to the model service in the warnings field of the response, but nothing surfaces them yet — a malformed row currently shows up as a missing or oddly-valued object rather than as a message in the editor.

Server-side capabilities

Key	Contents
ast	The serialised AST of the import block

The plugin answers the model plugin's request for imported objects. The model service hands over the text of the import CSV block together with a description of the metamodel's classes; this plugin parses that text, reads the referenced .csv files itself, and returns instances and links which the model service merges into the model data the execution services consume.

Class names arrive as plain reference text rather than as resolved references, because the metamodel document is not loaded in this service — the model service has already validated them.