shacl-form

This repository contains a Python package that generates HTML + JS webforms from given W3C Shapes Constraint Language (SHACL) "shapes". The intention is to allow for the auto-generation of web UIs, given only a logical expression of the required data that the UI is to facilitate the input of. Additionally, this can convert submitted form data back into RDF format.

License

This work is licensed using the GPL v3 license. See LICENSE for the deed.

Contacts

This work is being conducted by a Griffith University Industrial Placement student at the CSIRO.

Laura Guillory
Lead Developer
Griffith University Industrial Placement Student at CSIRO Land & Water
laura.guillory@griffithuni.edu.au

Nicholas Car
Product Owner
Senior Experimental Scientist
CSIRO Land & Water
nicholas.car@csiro.au

How to use

This package is intended to fulfil two main functions - to convert a SHACL Shapes file into a HTML + JS webform, and to convert form data back into RDF format.

Please see the example at shacl-form-example.

Supplying a SHACL shapes file
A SHACL Shapes file must be supplied to define the data that the form accommodates. While optional, it is ideal to use the SHACL constraints sh:name, sh:description and sh:order. These are non-validating SHACL properties that will improve the appearance of the form.

This tool is intended to generate a form for only one Shape at a time, though a Shape may consist of multiple NodeShapes. If multiple NodeShapes are present in the file, this tool will attempt to determine which NodeShape is the 'root' Shape. If two unrelated NodeShapes are present, only one will be present in the form and results may be inconsistent.

Generating the webform
Use generate_form(). You must supply a Shapes Graph or a file-like object containing a SHACL Shape in RDF Turtle format. You must also supply the desired destination for of the HTML form and the RDF map file.

It will generate two files:

• view/templates/form_contents.html is a Jinja2 template which extends form.html. You will want to edit form.html to control where the form appears on your site.
• map.ttl is a Turtle RDF file which is used to convert information submitted to the form back into RDF.

These two files are a pair and can't be interchanged with files generated for another shape.

If you want to run this tool from the command line, use:

python generate_form.py <SHACL file path> <optional: HTML form destination> <optional: RDF map destination>

Converting form data
Use Form2RDFController, supplying the base_uri (which determines the URI that will be generated for the entries submitted by the form), the request received from the form, and the path of map.ttl.

It will return an RDF graph containing the data that was submitted to the form.

Supported constraints

These constraints are optional unless stated otherwise.

Each property in a supplied SHACL Shapes file corresponds to one input field in the resulting webform. Each constraint applied to a property affects the corresponding input field in the following ways:

sh:path
Determines the HTML name of the input field, and if there is no sh:name, determines the user-readable label that accompanies the input field. A required constraint, since the sh:path defines its property in a Shape.

sh:nodeKind
Determines what kind of node the property refers to. Options for sh:NodeKind are: sh:Literal, sh:IRI, sh:BlankNode, sh:BlankNodeOrIRI, sh:IRIOrLiteral, sh:BlankNodeOrLiteral

1. Literal - Entered as a plain value (for example, a string, number or date) with constraints applying as normal
2. IRI - A pattern is applied to ensure the value entered looks like an IRI, but the validity of the IRI is not checked. An IRI should refer to a node that already exists. For example, you might want a person to be a supervisor of another person, so you would enter the IRI of the other person.
3. BlankNode - The property will consist of other properties. For example, an address will be made up of a street name, postcode, country, etc.
4. BlankNodeOrIRI - The user can pick between entering a BlankNode or IRI
5. IRIOrLiteral - The user can pick between entering an IRI or Literal
6. BlankNodeOrLiteral - The user can pick between entering a Blank Node or Literal.

If the property doesn't fit the specified nodeKind, shacl-form will provide a warning and the property will look odd/empty.

sh:name
Determines the user-readable label that accompanies the input field.

sh:description
Determines the user-readable description that accompanies the input field.

sh:defaultValue
Determines the default value of the input field.

sh:group
Determines the group that the input field belongs to. All input fields belonging to a group will appear together. The group must refer to an existing Property Group in the SHACL Shapes file. The Property Group may use rdfs:label to specify the label for the group of properties, and may use sh:order to specify the order in which groups appear (if there are multiple groups).

sh:order
Determines the order in which the input fields appear. Also used in Property Groups to determine the order in which groups appear. The order is as follows:

1. All ordered groups in ascending order

   • (Within each group) All ordered properties in ascending order
   • (Within each group) All unordered properties

2. All unordered groups

   • (Within each group) All ordered properties in ascending order
   • (Within each group) All unordered properties

3. All ungrouped ordered properties in ascending order

4. All ungrouped unordered properties

sh:minCount
Determines the minimum number of input fields that may be present for each property.

sh:maxCount
Determines the maximum number of input fields that may be present for each property.

sh:in
Should supply a list of options. The input field will be a dropdown containing all the options.

sh:datatype
The datatype will determine the input field type.

Datatype	Input Type
xsd:integer, xsd:float, xsd:double	number
xsd:date	date
xsd:time	time
xsd:boolean	checkbox

Otherwise, it will be of type text.

sh:minInclusive
Will set the minimum accepted value of the input field, including the value provided. The user will not be able to submit values outside the accepted range.

sh:maxExclusive
Will set the maximum accepted value of the input field, excluding the value provided. The user will not be able to submit values outside the accepted range.

sh:maxInclusive
Will set the maximum accepted value of the input field, including the value provided. The user will not be able to submit values outside the accepted range.

sh:minExclusive
Will set the minimum accepted value of the input field, excluding the value provided. The user will not be able to submit values outside the accepted range.

sh:maxlength
Will set the maximum length of the input field.

sh:minLength Will set the minimum length of the input field.

sh:pattern
Will set the regex pattern of the input field. Note that a blank field will still be accepted unless the field is also required. ^ and $ will be added around the pattern provided.

sh:flags
For use with sh:pattern. The flags set the modifier to be used with the regex expression. Available flags: m, i

sh:hasValue
This input field will be present when the form is submitted, but will be hidden from the user.

sh:equals
This input field will be required to equal the referenced property. Note that unless the field is required, an empty field will be valid.

sh:disjoint
This input field will not be permitted to equal the referenced property.

sh:lessThan
This input field must have a value that is less than the referenced property.

sh:lessThanOrEquals
This input field must have a value that is less than or equal to the referenced property.

Other
foaf:mbox
If a property requires a foaf:mbox predicate, the corresponding input field will have input type email.

foaf:phone
If a property requires a foaf:phone predicate, the corresponding input field will have input type tel.

Other Features

Open/Closed Shapes
Shapes may have a property of sh:closed.
If sh:closed is True, only properties that are explicitly defined will be present in the form.
If sh:closed is False, the user will be able to add custom properties in addition to properties that have been explicitly defined
If sh:closed is absent, it will be assumed that it is equal to False.

If a Shape is closed, its form will also contain input fields for properties specified in sh:ignoredProperties.