Erebus NPM | npm.io

Erebus

Erebus is a data generation tool that:

is based on schema files, so changing the structure of the data is easy
is seeded, so it will always generate the same data as long as the seed remains constant*
can generate extremely interconnected data to better simulate real situations
can use different "flavors" of data, so you can pull names from Lord of the Rings, for example.

* note: changing the schemas will also (naturally) change the data generated.

How to use

This is kind of a weird thing to document. I'll do my best below, but you'll probably get a better feel for it by reading the tutorial.

npm install -g erebus

It takes several options, all of which can instead be put into an erebus.json file, if you prefer. Or whatever filename you pass with --config.

`schemaDir` (short: `-i`, default: `./schemas`)

The directory where your schema files reside.

`outputDir` (short: `-o`, default: `./data`)

The directory where the generated data will be written.

`flavor` (short: `-f`)

The dataset(s) from which to pull values when generating. You can declare multiple sources, for example

$ erebus -f asoiaf -f lotr

`fallback` (short: `-F`)

Make flavor selection fallback rather than merge (the default). Using the above example,

$ erebus -F -f asoiaf -f lotr

Erebus will first try to find a value in the asoiaf dataset, and only if that dataset lacks a generator for the requested value will it look at lotr.

`verbose` (short: `-v`)

Increase the verbosity. Only errors/warnings by default, -v includes some info, and -vv will spit out entirely too much.

`seed` (short: `-s`)

The seed to use when generating data. Can be a number or a string.

Schema format

Schema files should be objects, even if the data to generate is an array. The actual schema is a property of the object.

__generated__ - indicates that this file is one Erebus ought to parse. Otherwise it will be treated as a static datafile.
type - "Array" if this should generate an array of data, otherwise leave it out
count - [min, max] range of entries to generate
relatedData - an object, where each key is an alias to use, and each value is another object. The other object has:
- use - the name of the schema to which this alias refers
- count - another [min, max] type thing
- backRef - key/value pairs for references to put into the use-schema-generated data. The value is the current objects own properties.
schema - the actual schema. The keys are the real keys that will be used in the output, the values can be. If a value begins with "$", then it will look up that value in the datasets. If a value begins with "@", then it is a cross-reference, and it will look it up per relatedData (above).