How to make mongodb work with virtual graphs?

Support
1

this is my users collection.

image

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i'm trying to follow tuts from here

PREFIX : <http://kim.jong.un/onto#>

MAPPING <urn:users>
FROM JSON {
    "users": {
        "_id": "?id",
        "username": "?username"
    }
}
TO {
    ?user a :User;
        :username ?username .
}
WHERE {
    BIND (template("http://kim.jong.un/onto#{id}") AS ?user)
}

but no result were found.

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2

You probably need to declare the : prefix in your SPARQL query at the top:
prefix : <http://kim.jong.un/onto#>

3

weird i've this in Namespaces

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after adding this still doesn't return anything.

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4

Can you click "Show Plan" and then "Text" and paste it here? You can use three backticks to quote text blocks.

5 
prefix : <http://kim.jong.un/onto#>

Distinct [#1]
`─ Projection(?user, ?username) [#1]
   `─ Empty [#1]

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6

You've registered the virtual graph named "users", right? What happens if you put ?s ?p ?o in the graph <...> { block? Can you show the plan again?

7

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this is my ttl file and its almost empty

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@prefix : <http://kim.jong.un/onto#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@base <http://kim.jong.un/onto> .

<http://kim.jong.un/onto> rdf:type owl:Ontology .

#################################################################
#    Annotation properties
#################################################################

###  http://kim.jong.un/onto#标签名称
:标签名称 rdf:type owl:AnnotationProperty .


#################################################################
#    Data properties
#################################################################

###  http://kim.jong.un/onto#_id
:_id rdf:type owl:DatatypeProperty .


###  http://kim.jong.un/onto#username
:username rdf:type owl:DatatypeProperty .


#################################################################
#    Classes
#################################################################

###  http://kim.jong.un/onto#User
:User rdf:type owl:Class .


###  Generated by the OWL API (version 4.2.8.20170104-2310) https://github.com/owlcs/owlapi
8

Did you create the virtual graph? Can you show that tab?

9

Can you try it with reasoning disabled?

10

oh sorry i thought i put this in first comment

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and yes i've tried toggle reasoning

PREFIX : <http://kim.jong.un/onto#>

MAPPING <urn:users>
FROM JSON {
    "users": {
        "_id": "?id",
        "username": "?username"
    }
}
TO {
    ?user a :User;
        :username ?username .
}
WHERE {
    BIND (template("http://kim.jong.un/onto#{id}") AS ?user)
}
11

The virtual graph name showing in the screenshot is dezhi. In your SPARQL query, you should reference the graph virtual://dezhi.

1 Like
12

awesome

i thought virtual:// is from "keyword" after "MAPPING"

13

No, that's a way to refer to the mapping in the case of multiple mappings. I'll get the documentation updated to clarify this. Glad you got it working.

1 Like
14

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