JSON-LD schemas

The main schemas catalog is ips://galacteek.ld/ (accessible with the gs SparQL prefix by default).

Checkout the schemas here

Using SparQL models in your dapp

SparQL documentation

If you don't know SparQL yet here are a few resources to learn:

• SparQL tutorial
• SparQL by example

Declaring your model

From your dapp it's very easy to run SparQL requests and use the results as a Qt list model.

The SparQLCoreModel QML component allows you to specify the SparQL query and graph on which to run the query (if you don't specify graphUri it defaults to urn:ipg:i, the top conjunctive graph). The resulting model is compatible with Qt/QML's model/view system.

Here's an example model which retrieves a list of articles. Note that we use the gs prefix, which maps to ips://galacteek.ld/. You can consult all the available schemas here.

import GForce.models.sparql 1.0

SparQLCoreModel {
  id: amodel
  graphUri: 'urn:ipg:i'

  query: "
    SELECT *
    WHERE {
        ?uri a gs:Article ;
          gs:headline ?headline ;
          gs:dateCreated ?dateCreated .
    }
    ORDER BY DESC(?dateCreated)
  "
}

Bindings

You can use bindings when executing a request. Bindings are variables that will be substituted when the query is run. Here's an example where we filter articles with a regular expression.

import GForce.models.sparql 1.0

SparQLCoreModel {
  id: amodel
  query: "
    SELECT *
    WHERE {
        ?uri a gs:Article ;
          gs:headline ?headline ;
          gs:dateCreated ?dateCreated .
        FILTER(regex(?headline, str(?headlineRegexp), 'i'))
    }
  "

  bindings: { 'headlineRegexp': 'hello.*' }
}

Here we have a binding called headlineRegexp.

It's of course possible to change the bindings dynamically, but do not forget to call the run() function after changing them.

amodel.bindings = { 'headlineRegexp': 'hello.*' }
amodel.run()

You will most likely always define your model in a separate QML file (for example we could call it ArticlesModel.qml) and reuse it.

ArticlesModel {
  id: articles
  bindings: { 'headlineRegexp': 'hello.*' }
}

Use the model in a view

It's then very easy to render your model in a view. The names of the Qt roles are the same as the variables in your SparQL query, here we show the headline in the delegate.

import QtQuick.Controls 1.2

ListView {
  id: view
  model: amodel

  delegate: Text {
    text: headline
  }
}

Please note that if one of your SparQL bindings is a URI (as with the uri binding in the previous example), it will be passed to the Qt model as a string and not as a special url type.

Have a look at the gforce SparQL models for more examples.