datahub-tslib

A typescript module for writing datahub transform scripts with strict typing.

Usage

Prerequisites

the tt transpiler that comes with this package requires node version 17 or higher.

Installation

If you don't have an existing npm project yet, create one:

mkdir myproject && cd myproject
npm init

Install the datahub-tslib package.

npm install mimiro-io/datahub-tslib --save-dev

Now you have an executable available called tt, which takes the name of a typescript file as parameter and transpiles to javascript. You can add it as build script to package.json or call it directly using npx tt <filename.ts>.

package.json should look like this now:

{
    "scripts": {
        "build": "tt"
    },
    "devDendencies": {
        "datahub-tslib": "github:mimiro-io/datahub-tslib"
    }
}

Create and transpile a transform script.

To make use of the library, create a typescript file: touch mytransform.ts.

Now add an import for our datahub module from datahub-tslib, and add a global scope function called transform_entities with the signature given in the following example.

import * as dh from "datahub-tslib/datahub"

export function transform_entities(entities: dh.Entity[]): dh.Entity[] {
    entities.forEach((e: dh.Entity) => {
        dh.Log(dh.GetId(e))
    })
}

To transpile the typescript transform to javascript, run:

npx tt mytransform.ts

or, if you added tt as build script to package.json:

npm run build mytransform.ts

Given there are no compilation errors, this will emit transpiled and bundled javascript code, which can be used as transform in a datahub job.