On 2021-09-22 11:01 am, Maatary Okouya wrote:
I assumed that in my example that the list is made up of blank
Property Shape? am i correct ?
```
ex:PersonAddressShape a sh:NodeShape ;
sh:targetClass ex:Person ;
sh:property [ //shprop1
sh:path ex:address ;
sh:or (
[ //shprop2
sh:datatype xsd:string ;
]
[ //shprop3
sh:class ex:Address ;
]
)
] .
```
The prop2 and prop3 constraints above are node shapes. But they are
applied to all value nodes of the surrounding property shape.
Hence i am interested in how one read this informally as much as
formally. I don't think, as in the previous example above, sh:node or
sh:property applies. Hence, little confused on this one
In general, both types of shapes apply to a focus node and its value
node(s). For node shapes the value node == the focus node. If you would do
ex:PersonAddressShape
sh:property [
sh:path ex:address ;
sh:or (
[
sh:path ex:postalCode ;
sh:maxLength 4 ;
sh:minCount 1 ;
]
...
this would mean that all value nodes of ex:address must have another
property ex:postalCode with min length 4.
So basically the terminology "focus node" and "value node" matters a
lot. Once this is clear, both types of shapes can be used interchangeably.
In the WG we had long long discussions about whether property shapes and
node shapes can be used interchangeably, and I was hesitant and actually
actively against too much flexibility here because it would confuse
users. Sometimes less is more, and I believe your discussion and input
from many other users have confirmed that the current design requires
quite a level of abstraction to understand properly.
Holger
/Note: I have been using all of this thing in my application
without problem, as i had the intuition about how those works and the
support of TBC. But recently i have had to parse shacl, and that is
when the issue of what is what exactly, or what is allowed where
comes in.
/
On Wednesday, September 22, 2021 at 1:44:32 AM UTC+1 Maatary Okouya wrote:
Just to conclude and be complete about my last question, which is
all that sparked the original question actually:
/(Note: I'm using rdfs:subclassOf informally here, just to
express the idea)/
When we have
```
ex:PersonAddressShape a sh:NodeShape ;
sh:targetClass ex:Person ;
sh:property [ //shprop1
sh:path ex:address ;
sh:or (
[ //shprop2
sh:datatype xsd:string ;
]
[ //shprop3
sh:class ex:Address ;
]
)
] .
```
Are we saying that shProp1 rdfs:subClassOf at least shProp1 or shProp2
On Wednesday, September 22, 2021 at 1:35:56 AM UTC+1 Maatary
Okouya wrote:
1 - Does that mean that fundamentally, the list of shape in an
sh:Or or sh:And is heterogenous ? That is, it may contain both
propertyShape and NodeShape at the same time ?
2 - This bring me to the question of how to read this ?
>>>>
ex:ExampleAndShape a sh:NodeShape ;
sh:targetNode ex:ValidInstance, ex:InvalidInstance ;
sh:and (
ex:SuperShape
[
sh:path ex:property ;
sh:maxCount 1 ;
] ) .
>>>>
2-1 - With respect to s:SuperShape: is it saying that
ex:ExampleAndShap rdfs:SubClassOf ex:SuperShape ?
2-2 - With respect to
[
sh:path ex:property ;
sh:maxCount 1 ;
]
is it saying
ex:ExampleAndShape *has the propertyshape i.e. sh:property*
[
sh:path ex:property ;
sh:maxCount 1 ;
]
???
On Wednesday, September 22, 2021 at 1:01:59 AM UTC+1 Holger
Knublauch wrote:
On 2021-09-22 9:54 am, Maatary Okouya wrote:
Taken from the specification:
>>>
A node shape is a shape
<https://www.w3.org/TR/shacl/#dfn-shape> in the shapes
graph
<https://www.w3.org/TR/shacl/#dfn-shapes-graph> that is
not the subject
<https://www.w3.org/TR/shacl/#dfn-subject> of a triple
<https://www.w3.org/TR/shacl/#dfn-rdf-triple> with
*sh:path* as its predicate
<https://www.w3.org/TR/shacl/#dfn-predicate>. SHACL
instances
<https://www.w3.org/TR/shacl/#dfn-shacl-instance> of sh:NodeShape
cannot
have a value <https://www.w3.org/TR/shacl/#dfn-value> for
the property sh:path.
>>>
Yet when talking Or Constraint or And Constraint, that
takes list of shapes, we find example like what follow:
>>>>
ex:SuperShape a sh:NodeShape ;
sh:property [ sh:path ex:property ; sh:minCount 1 ; ] .
ex:ExampleAndShape a sh:NodeShape ;
sh:targetNode ex:ValidInstance, ex:InvalidInstance ;
sh:and (
ex:SuperShape
[
sh:path ex:property ;
sh:maxCount 1 ;
] ) .
>>>>
With the following explanation
>>>
The following example illustrates the use of sh:and in a
shape to specify the condition that certain focus nodes
have exactly one value of ex:property. This is achieved
via the conjunction of a separate named shape
(ex:SuperShape) which specifies the minimum count, and a
*blank node shape* that additionally specifies the
maximum count. As shown here, sh:and can be used to
implement a specialization mechanism between shapes.
>>>>
How on earth is this a Blank Node shape if it is the
subject of an sh:path, am I missing something ?
It should be a "blank property shape". I have recorded a
bug report to the spec's Errata:
https://github.com/w3c/data-shapes/issues/140
<https://github.com/w3c/data-shapes/issues/140>
Note the error is in an informative block of text, so it
doesn't change implementations.
Thanks for pointing this out
Holger
```
[
sh:path ex:property ;
sh:maxCount 1 ;
]
```
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