Class TaliaCore::RdfResource
In: lib/talia_core/rdf_resource.rb
Parent: Object

This class encapsulates all functionality to access a specific resource in the RDF store. It is analogous to the RDFS::Resource class in ActiveRDF.

However, it‘s specifically tailored for the use with Talia, and avoids some of the pitfalls of the original class.

Methods

[]   clear_rdf   default_types   direct_predicates   direct_write_predicate   inverse   inverse_predicates   new   object_class   remove   save   types   uri  

Included Modules

ActiveRDF::ResourceLike

Attributes

object_class  [W]  The class of objects that will be "produced" by this RdfResource

Public Class methods

default_types()

A list of "default" types that will be added to all resources

[Source]

    # File lib/talia_core/rdf_resource.rb, line 15
15:       def default_types
16:         @default_types ||= [
17:           N::SourceClass.new(N::RDFS.Resource)
18:         ]
19:       end
new(uri)

Initialize a new resource with the given URI

[Source]

    # File lib/talia_core/rdf_resource.rb, line 31
31:     def initialize(uri)
32:       raise ArgumentError, "No blank URI allowed here" if(uri.to_s.blank?)
33:       @uri = N::URI.new(uri)
34:     end

Public Instance methods

[](predicate)

Returns the value(s) of the given predicates as a PropertyList filled with the defined object_class objects.

[Source]

    # File lib/talia_core/rdf_resource.rb, line 54
54:     def [](predicate)
55:       predicate = N::URI.new(predicate) unless(predicate.kind_of?(N::URI))
56:       
57:       property_list = ActiveRDF::Query.new(object_class).distinct(:o).where(self, predicate, :o).execute
58:       
59:       PropertyList.new(predicate, property_list, self, source_exists?)
60:     end
clear_rdf()

Clears all rdf for this resource. FIXME: Not context-aware.

[Source]

    # File lib/talia_core/rdf_resource.rb, line 42
42:     def clear_rdf
43:       ActiveRDF::FederationManager.delete_all(self)
44:     end
direct_predicates()

Returns the predicates that are directly defined for this resource

[Source]

    # File lib/talia_core/rdf_resource.rb, line 96
96:     def direct_predicates
97:       ActiveRDF::Query.new(N::Predicate).distinct(:p).where(self, :p, :o).execute
98:     end
direct_write_predicate(predicate, value)

Direct writing of a predicate, with having to fetch a list first

[Source]

    # File lib/talia_core/rdf_resource.rb, line 37
37:     def direct_write_predicate(predicate, value)
38:       ActiveRDF::FederationManager.add(self, predicate, value)
39:     end
inverse()

Returns an on-the-fly object that can be used to query for "inverse" properties of this resource (meaning triples that have the current resource as an object.)

The returned object will respond to a [] (array accessor) call which allows the user to specify the predicate to use.

Example: resource.inverse[N::DNCS::title]

The [] method will return a list of objects that are instances of object_class

[Source]

    # File lib/talia_core/rdf_resource.rb, line 72
72:     def inverse
73:       inverseobj = Object.new
74:       inverseobj.instance_variable_set(:@obj_uri, self)
75:       inverseobj.instance_variable_set(:@obj_class, object_class)
76:       
77:       class <<inverseobj     
78:         
79:         def [](property)
80:           property = N::URI.new(property) unless(property.kind_of?(N::URI))
81:           ActiveRDF::Query.new(@obj_class).distinct(:s).where(:s, property, @obj_uri).execute
82:         end
83:         private(:type)
84:       end
85:       
86:       return inverseobj
87:     end
inverse_predicates()

Returns the "inverse" predicates for the resource. these are the predicates for which this resource exists as an object

[Source]

     # File lib/talia_core/rdf_resource.rb, line 102
102:     def inverse_predicates
103:       qry = ActiveRDF::Query.new.distinct.select(:p)
104:       qry.where(:s, :p, N::URI.new(uri.to_s))
105:       qry.execute.collect{ |res| N::Predicate.new(res.uri) }
106:     end
object_class()

[Source]

    # File lib/talia_core/rdf_resource.rb, line 26
26:     def object_class
27:       @object_class ||= TaliaCore::Source
28:     end
remove(predicate, value = nil)

Removes the given predicate (restrict to the triple with the given value if a value is given).

[Source]

    # File lib/talia_core/rdf_resource.rb, line 48
48:     def remove(predicate, value = nil)
49:       ActiveRDF::FederationManager.delete(self, predicate, value)
50:     end
save()

Saves the current resource and it‘s properties to the RDF. (This has been optimized so that if only one RDF backend is present it won‘t do any copying around.

[Source]

     # File lib/talia_core/rdf_resource.rb, line 111
111:     def save
112:       if((ActiveRDF::ConnectionPool.read_adapters.size == 1) &&
113:             (ActiveRDF::ConnectionPool.write_adapter == ActiveRDF::ConnectionPool.read_adapters.first))
114:         save_default_types # Only write the "default" types to the store
115:       else
116:         full_save # Do the full save operation
117:       end
118:     end
types()

Returns the types of this resource as N::SourceClass objects

[Source]

     # File lib/talia_core/rdf_resource.rb, line 121
121:     def types
122:       types = ActiveRDF::Query.new(N::SourceClass).distinct(:t).where(self,N::RDF::type,:t).execute
123:       # Add the "default" types if necessary
124:       self.class.default_types.each do |def_type|
125:         types << def_type unless(types.include?(def_type))
126:       end
127:       
128:       # Make a property list for the types.
129:       PropertyList.new(N::RDF::type, types, self, source_exists?)
130:     end
uri()

Returns the uri of this resource as a string

[Source]

    # File lib/talia_core/rdf_resource.rb, line 91
91:     def uri
92:       @uri.to_s
93:     end

[Validate]