Class: Pho::Update::ChangesetBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/pho/changeset_builder.rb

Overview

Utility class providing methods for building Changesets from triple hashes

Class Method Summary collapse

Class Method Details

.build(subject_of_change, before, after, creator_name = nil, change_reason = nil) ⇒ Object

Build a single changeset

This method is suitable for building changesets that describe changes made to a single resource If the before/after hashes contain data for other subjects, then an error will be thrown.

The method will return a single Changeset object.

subject_of_change

uri of the resource being updated

before

resource hash describing current state of the resource

after

resource hash describing updated state of the resource

creator_name

name of the creator of the changes

change_reason

description of why the changes are being made



65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/pho/changeset_builder.rb', line 65

def ChangesetBuilder.build(subject_of_change, before, after, creator_name=nil, change_reason=nil)
  removals = Pho::ResourceHash::SetAlgebra.minus(before, after)
  additions = Pho::ResourceHash::SetAlgebra.minus(after, before)
  
  cs = Pho::Update::Changeset.new(subject_of_change, creator_name, change_reason) do |cs|
      cs.add_removals( create_statements(removals) )
      cs.add_additions( create_statements(additions) )      
  end
  
  return cs
  
end

.build_batch(before, after, creator_name = nil, change_reason = nil) ⇒ Object

Build a batch changeset

This method is suitable for building an array of changesets that describe changes made to a number of different resources.

Returns an array of Changeset objects

before

resource hash describing current state of the resource

after

resource hash describing updated state of the resource

creator_name

name of the creator of the changes

change_reason

description of why the changes are being made



22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
 
# File 'lib/pho/changeset_builder.rb', line 22

def ChangesetBuilder.build_batch(before, after, creator_name=nil, change_reason=nil)

  removals = Pho::ResourceHash::SetAlgebra.minus(before, after)
  additions = Pho::ResourceHash::SetAlgebra.minus(after, before)
  
  batch = Array.new
  
  removals.each do |uri, properties|
    cs = Pho::Update::Changeset.new(uri, creator_name, change_reason) do |cs|
        cs.add_removals( create_statements_for_uri(uri, properties) )
        if additions.has_key?(uri)
          cs.add_additions( create_statements_for_uri(uri, additions[uri] ) )
          additions.delete(uri)
        end      
    end
    batch << cs
  end
  
  if !additions.empty?
    additions.each do |uri, properties|
      cs = Pho::Update::Changeset.new(uri, creator_name, change_reason) do |cs|
          cs.add_additions( create_statements_for_uri(uri, properties) )
      end
      batch << cs            
    end
  end
  
  return batch
  
end

.create_statements(triples) ⇒ Object

Takes a resource hash and serializes it as an array of Pho::Update::Statement objects

triples

a resource hash, conforming to RDF-in-JSON structure



81
82
83
84
85
86
87
 
# File 'lib/pho/changeset_builder.rb', line 81

def ChangesetBuilder.create_statements(triples)
  statements = Array.new
  triples.each do |uri, properties|
     statements += create_statements_for_uri(uri, properties)
  end
  return statements
end

.create_statements_for_uri(uri, properties) ⇒ Object

Create statements for a specific uri, using predicate-object values in the provided properties hash

uri

subject of change

properties

hash of predicate-object values



94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
 
# File 'lib/pho/changeset_builder.rb', line 94

def ChangesetBuilder.create_statements_for_uri(uri, properties)
  statements = Array.new
  properties.each do |predicate, val_array|
    val_array.each do |value|
      s = nil
      if value["type"] == "literal"
          s = Pho::Update::Statement.create_literal(uri, predicate, value["value"], value["lang"], value["datatype"])
      else
          #TODO bnodes?
          s = Pho::Update::Statement.create_resource(uri, predicate, value["value"])
      end
      if s != nil
        statements << s
      end
    end
  end
  return statements        
end