Generate simple SPARQL SELECT queries

[lecoqlibre]

In order to query and find data, we should be able to generate a simple SPARQL SELECT query.

This query should support WHERE parameters constructed from the semantic properties.

To do so, we could define a SparqlQueryParameter interface like:

interface SparqlQueryParameter {
    property: string;
    values: string[] | Semanticable[];
}

Then the method could take the form of a static method getSparqlSelectQuery(parameters?: SparqlQueryParameter[]).

Maybe this should not be part of the SemanticObject class? The Decorator design pattern could also be used.

Note: we don't to generate SPARQL queries in the connector codegen to keep it simple. It's better to have this is Semantizer.

Use object as criteria

In the SemanticObject class we could have a find method:

SemanticObject.find() {
    // 1. Generate the SPARQL from all the semantic properties of the object.
    // 2. Create a cancel-able command containing the SPARQL.
    // 3. Send the command to the query planner.
}

Then we can create semantic objects for finding:

new SemanticObject(params...).find()

--> PB when we want to query several values for a property with only one value allowed.

Use findBy methods

Create findBy... methods like:

public static async Catalog.findByMaintainer(connector: IConnector, maintainer: Semanticable callback: Function): Promise<void> {
    return connector.find(Catalog.TYPE, maintainer, callback);
}

public async Connector.findCatalogByMaintainer(maintainer: Semanticable, callback: Function): Promise<void> {
    return this.getSemantizer().find("dfc-b:Catalog", "dfc-b:maintainedBy", maintainer, callback);
}

// Or with collections:
Connector.catalog.findByMaintainer();
Connector.address.findByCountry();