npm i @ulb-darmstadt/shacl-formHTML5 web component for editing/viewing RDF data that conform to SHACL shapes.
<html>
<head>
<!-- load web component -->
<script src="https://cdn.jsdelivr.net/npm/@ulb-darmstadt/shacl-form/dist/form-default.js" type="module"></script>
</head>
<body>
<!--
SHACL shapes can be defined on the attribute 'data-shapes'
or can be loaded by setting attribute 'data-shapes-url'
-->
<shacl-form data-shapes="
@prefix sh: <http://www.w3.org/ns/shacl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix ex: <http://example.org#> .
ex:ExampleShape
a sh:NodeShape, rdfs:Class ;
sh:property [
sh:name 'my value' ;
sh:path ex:exampleValue ;
sh:maxCount 3 ;
] .
"></shacl-form>
<script>
const form = document.querySelector("shacl-form")
form.addEventListener('change', event => {
// check if form data validates according to the SHACL shapes
if (event.detail?.valid) {
// get data graph as RDF triples and
// log them to the browser console
const triples = form.serialize()
console.log('entered form data', triples)
// store the data somewhere, e.g. in a triple store
}
})
</script>
</body>
</html>| Attribute | Description |
|---|---|
| data-shapes | SHACL shape definitions (e.g. a turtle string) to generate the form from |
| data-shapes-url | When data-shapes is not set, the SHACL shapes are loaded from this URL |
| data-shape-subject | Optional subject (id) of the SHACL node shape to use as root for the form. If not set, the first found node shape will be used |
| data-values | RDF triples (e.g. a turtle string) to use as existing data graph to fill the form |
| data-values-url | When data-values is not set, the data graph triples are loaded from this URL |
| data-value-subject | The subject (id) of the generated data. If this is not set, a blank node with a new UUID is created. If data-values or data-values-url is set, this id is also used to find the root node in the data graph to fill the form |
| data-values-namespace | RDF namespace to use when generating new RDF subjects. Default is empty, so that subjects will be blank nodes. |
| data-language | Language to use if shapes contain langStrings, e.g. in sh:name or rdfs:label. Default is navigator.language |
| data-loading | Text to display while the web component is initializing. Default: "Loading..." |
| data‑ignore‑owl‑imports | By default, owl:imports URLs are fetched and the resulting RDF triples are added to the shapes graph. Setting this attribute to any value disables this feature |
| data-view | When set, turns the web component into a viewer that displays the given data graph without editing functionality |
| data-collapse | When set, sh:groups and properties with sh:node and sh:maxCount != 1 are displayed in a collapsible accordion-like widget to reduce visual complexity of the form. The collapsible element is initially shown closed, except when this attribute's value is "open" |
| data-submit-button | [Ignored when data-view attribute is set] Whether to add a submit button to the form. The value of this attribute is used as the button label. submit events get emitted only when the form data validates |
toRDF(graph?: Store): StoreAdds the form values as RDF triples to the given graph. If no graph object is provided, creates a new N3 Store.
serialize(format?: string, graph?: Store): stringSerializes the given RDF graph to the given format. If no graph object is provided, this function calls toRDF() (see above) to construct the form data graph. Supported formats: text/turtle (default), application/ld+json, application/n-triples, application/n-quads, application/trig.
validate(ignoreEmptyValues: boolean): Promise<boolean>Validates the form data against the SHACL shapes graph and displays validation results as icons next to the respective input fields. If ignoreEmptyValues is true, empty form fields will not be marked as invalid. This function is also internally called on change and submit events.
registerPlugin(plugin: Plugin)Register a plugin to customize editing/viewing certain property values. Plugins handle specific RDF predicates or xsd:datatypes or both. Examples: Leaflet, Mapbox, FixedList
setTheme(theme: Theme)Set a design theme to use for rendering. See section Theming.
setClassInstanceProvider((className: string) => Promise<string>)Sets a callback function that is called when a SHACL property has an sh:class definition. The expected return value is a string (e.g. in format text/turtle) that contains RDF class instance definitions of the given class. Instances can be defined e.g. like:
example:Instance a example:Classexample:Instance a owl:NamedIndividual; skos:broader example:Class
Class hierarchies can be built using rdfs:subClassOf or skos:broader.
In edit mode, <shacl-form> validates the constructed data graph using the library rdf-validate-shacl and displays validation results as icons next to the respective form fields.
<shacl-form> requires only a shapes graph as input via the attribute data-shapes (or data-shapes-url) to generate an empty form and create new RDF data from the form input fields. Using the attributes data-values (or data-values-url) and data-value-subject, you can also bind an existing data graph to the form. The given data graph is then used to fill the form input fields.
<shacl-form> not only is an RDF data editor, but can also be used as a viewer by setting attribute data-view and binding both, a shapes and a data graph. See the demo for an example.
Apart from setting the element attributes data-shapes or data-shapes-url, there are two ways of adding RDF data to the shapes graph:
-
While parsing the triples of the shapes graph, any encountered
owl:importspredicate that has a valid HTTP URL value will tried to be fetched with the HTTP Accept header set to all of the supported MIME types. A successful response will be parsed and added to the shapes graph. The example shapes graph contains the following triples:example:Attribution owl:imports <https://w3id.org/nfdi4ing/metadata4ing/> ; sh:property [ sh:name "Role" ; sh:path dcat:hadRole ; sh:class prov:Role ; ] .In this case, the URL references an ontology which among other things defines instances of class
prov:Rolethat are then used to populate the "Role" dropdown in the form. -
The
<shacl-form>element has a functionsetClassInstanceProvider((className: string) => Promise<string>)that registers a callback function which is invoked when a SHACL property has ansh:classpredicate. The expected return value is a (promise of a) string (e.g. in formattext/turtle) that contains RDF class instance definitions of the given class. Instances can be defined e.g. like:example:Instance a example:Classexample:Instance a owl:NamedIndividual; skos:broader example:Class
Class hierarchies can be built using
rdfs:subClassOforskos:broader.In this example, the code:
form.setClassInstanceProvider((clazz) => { if (clazz === 'http://example.org/Material') { return ` <http://example.org/steel> a <http://example.org/Material>; <http://www.w3.org/2000/01/rdf-schema#label> "Steel". <http://example.org/wood> a <http://example.org/Material>; <http://www.w3.org/2000/01/rdf-schema#label> "Wood". <http://example.org/alloy> a <http://example.org/Material>; <http://www.w3.org/2000/01/rdf-schema#label> "Alloy". <http://example.org/plaster> a <http://example.org/Material>; <http://www.w3.org/2000/01/rdf-schema#label> "Plaster". ` } )
returns instances of the class
http://example.org/Materialthat are then used to populate the "Artwork material" dropdown in the form.A more realistic use case of this feature is calling some API endpoint to fetch class instance definitions from existing ontologies.
<shacl-form> supports using sh:or to let users select between different options on nodes or properties.
The example shapes graph has the following triples:
example:Attribution
a sh:NodeShape ;
sh:property [
sh:maxCount 1 ;
sh:minCount 1 ;
sh:path prov:agent ;
sh:or (
[ sh:node example:Person ; rdfs:label "Person" ]
[ sh:node example:Organisation ; rdfs:label "Organisation" ]
)
] .
When adding a new attribution, <shacl-form> renders a dropdown to let the user select between the two options Person/Organisation. After selecting one of the options, the dropdown is replaced by the input fields of the selected node shape.
When binding an existing data graph to the form, the sh:or constraint is tried to be resolved depending on the respective data value:
- For RDF literals, an
sh:oroption with a matchingsh:datatypeis chosen - For blank nodes or named nodes, the
rdf:typeof the value is tried to be matched with a node shape having a correspondingsh:targetClassor with a property shape having a correspondingsh:class
SHACL defines two ways of inheriting shapes: sh:and
and sh:node. <shacl-form> supports both. In this example, node shape example:ArchitectureModelDataset extends example:Dataset by defining the following RDF triple:
example:ArchitectureModelDataset sh:node example:Dataset .
Properties of inherited shapes are displayed first.
Plugins can modify rendering of the form and add functionality to edit and view certain RDF datatypes or predicates (or a combination of both). As an example, the JavaScript of this page contains the following code:
import { LeafletPlugin } from '@ulb-darmstadt/shacl-form/plugins/leaflet.js'
const form = document.getElementById("shacl-form")
form.registerPlugin(new LeafletPlugin({ datatype: 'http://www.opengis.net/ont/geosparql#wktLiteral' }))In effect, whenever a SHACL property has an sh:datatype of http://www.opengis.net/ont/geosparql#wktLiteral, the plugin is called to create the editor and/or viewer HTML elements. This specific plugin uses Leaflet to edit or view geometry in format well known text on a map.
Custom plugins can be built by extending class Plugin.
Properties can be grouped using sh:group in the shapes graph. This example defines a group "Physical properties" and assigns certain properties to it.
When the element attribute data-collapse is set, <shacl-form> creates an accordion-like widget that toggles the visibility of grouped properties in order to reduce the visual complexity of the form. If the grouped properties should initially be shown, set data-collapse="open".
Apart from grouped properties, all properties having an sh:node predicate and sh:maxCount != 1 are collapsed.
<shacl-form> comes in 3 different bundles, each providing a specific theme. See the demo page for an example.
| Theme | Import statement |
|---|---|
| Default (slightly customized default browser styles) | import '@ulb-darmstadt/shacl-form/form-default.js' |
| Bootstrap [alpha status] | import '@ulb-darmstadt/shacl-form/form-bootstrap.js' |
| Material Design [alpha status] | import '@ulb-darmstadt/shacl-form/form-material.js' |
Custom themes can be employed by extending class Theme, then calling function setTheme() on the <shacl-form> element.