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rdfInterface2easyRdf

A library providing methods for converting between EasyRdf (original library, still maintained fork) and rdfInterface objects (in both directions).

Helpful especially when you have too much EasyRdf code to port it but you would like to develop new code using the rdfInterface ecosystem.

Installation

• Obtain the Composer
• Run composer require sweetrdf/rdfInterface2easyRdf
• Install EasyRdf implementation of your choice, e.g. composer require sweetrdf/easyrdf.
• Install rdfInterface implementation of your choice, e.g. composer require sweetrdf/quick-rdf.

Usage

rdfInterface to EasyRdf

Conversion in this direction is straightforward:

• If you don't care about strong result type checks, just use the rdfInterface2easyRdf\AsEasyRdf::asEasyRdf() method, e.g.:

  • If you want converted data to be appended to an already existing graph, pass it as a second parameter, e.g. (continuing the code from the previous example):
• If you care about stictly defined return data types, use rdfInterface2easyRdf\AsEasyRdf::asLiteral(), rdfInterface2easyRdf\AsEasyRdf::asResource() and rdfInterface2easyRdf\AsEasyRdf::asGraph().
  • Each of them accepts only compatible input types, e.g. rdfInterface2easyRdf\AsEasyRdf::asLiteral() accepts only rdfInterface\LiteralInterface
  • rdfInterface\NodeInterface is accepted both by rdfInterface2easyRdf\AsEasyRdf::asResource() and rdfInterface2easyRdf\AsEasyRdf::asGraph()
  • An EasyRdf\Graph can be passed as an optional second parameter just as with rdfInterface2easyRdf\AsEasyRdf::AsEasyRdf() (see the example above)

EasyRdf to rdfInterface

Conversion in this direction might get tricky. Important remarks:

• As the rdfInterface defines only an interface but no actual implementation, you must always pass an RDF terms factory object (the $dataFactory parameter).
• As the rdfInterface doesn't define a standardized way to create datasets (rdfInterface\DatasetInterface) and dataset nodes (rdfInterface\DatasetNodeInterface) the asRdfInterface() method returns an rdfInterface\QuadIteratorInterface which is a triples iterator. The only way to convert an EasyRdf\Resource or EasyRdf\Graph to a dataset or dataset node is to add triples from the EasyRdf object to an existing rdfInterface\DatasetInterface or rdfInterface\DatasetNodeInterface. The add(), addDataset() and addDatasetNode() methods can be used for that (see examples below).
• There's an ambiguity around the EasyRdf\Resource conversion. You may want convert it to an RDF term (rdfInterface\BlankNode or rdfInterface\NamedNode) or you may want to convert it to a set of triples (quad iterator, dataset or dataset node).
  • The asRdfInterface() method converts to an RDF term if the EasyRdf\Resource object has no properties (no triples) and to a rdfInterface\QuadIteratorInterface otherwise.
  • Use asTerm(), asQuadIterator(), add(), addDataset() or addDatasetNode() to enforce a more specific behavior.

A sample EasyRdf graph and terms factory used in examples below:

• Use asRdfInterface() to guess the output type based on the input.

• Use asTerm() to enforce conversion of an EasyRdf\Resource to a term:

• There are two ways of converting an EasyRdf\Graph and EasyRdf\Resource to a dataset:

• Conversion of an EasyRdf\Resource to a dataset node is relatively most complex:

• In case of add(), addDataset() and addDatasetNode() the parameter used to pass a dataset/dataset node accepts also a callable, e.g.