Class: ActiveFacts::Metamodel::EntityType

Inherits:
Object
  • Object
show all
Defined in:
lib/activefacts/generators/transform/surrogate.rb

Instance Method Summary collapse

Instance Method Details

#identifying_refs_from ⇒ Object 



80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
 
# File 'lib/activefacts/generators/transform/surrogate.rb', line 80

def identifying_refs_from
  pi = preferred_identifier
  rrs = pi.role_sequence.all_role_ref

#       REVISIT: This is actually a ref to us, not from
#       if absorbed_via
#         return [absorbed_via]
#       end

  rrs.map do |rr|
    r = references_from.detect{|ref| rr.role == ref.to_role }
    raise "failed to find #{name} identifying reference for #{rr.role.object_type.name} in #{references_from.inspect}" unless r
    r
  end
end

#inject_surrogate ⇒ Object 



165
166
167
168
169
170
171
172
173
174
175
176
177
 
# File 'lib/activefacts/generators/transform/surrogate.rb', line 165

def inject_surrogate
  trace :transform_surrogate, "Injecting a surrogate key into #{self.name}"

  # Disable the preferred identifier:
  pi = preferred_identifier
  trace :transform_surrogate, "pi for #{name} was '#{pi.describe}'"
  pi.is_preferred_identifier = false
  @preferred_identifier = nil   # Kill the cache

  add_surrogate

  trace :transform_surrogate, "pi for #{name} is now '#{preferred_identifier.describe}'"
end

#needs_surrogate ⇒ Object 



96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
 
# File 'lib/activefacts/generators/transform/surrogate.rb', line 96

def needs_surrogate

  # A recursive proc to replace any reference to an Entity Type by its identifying references:
  trace :transform_surrogate_expansion, "Expanding key for #{name}"
  substitute_identifying_refs = proc do |object|
    if ref = object.absorbed_via
      # This shouldn't be necessary, but see the absorbed_via comment above.
      absorbed_into = ref.from
      trace :transform_surrogate_expansion, "recursing to handle absorption of #{object.name} into #{absorbed_into.name}"
      [substitute_identifying_refs.call(absorbed_into)]
    else
      irf = object.identifying_refs_from
      trace :transform_surrogate_expansion, "Iterating for #{object.name} over #{irf.inspect}" do
        irf.each_with_index do |ref, i|
          next if ref.is_unary
          next if ref.to_role.object_type.kind_of?(ActiveFacts::Metamodel::ValueType)
          recurse_to = ref.to_role.object_type

          trace :transform_surrogate_expansion, "#{i}: recursing to expand #{recurse_to.name} key in #{ref}" do
            irf[i] = substitute_identifying_refs.call(recurse_to)
          end
        end
      end
      irf
    end
  end
  irf = substitute_identifying_refs.call(self)

  trace :transform_surrogate, "Does #{name} need a surrogate? it's identified by #{irf.inspect}" do

    pk_fks = identifying_refs_from.map do |ref|
      ref.to && ref.to.is_table ? ref.to : nil
    end

    irf.flatten!

    # Multi-part identifiers are only allowed if:
    # * each part is a foreign key (i.e. it's a join table),
    # * there are no other columns (that might require updating) and
    # * the object is not the target of a foreign key:
    if irf.size >= 2
      if pk_fks.include?(nil)
        trace :transform_surrogate, "#{self.name} needs a surrogate because its multi-part key contains a non-table"
        return true
      elsif references_to.size != 0
        trace :transform_surrogate, "#{self.name} is a join table between #{pk_fks.map(&:name).inspect} but is also an FK target"
        return true
      elsif (references_from-identifying_refs_from).size > 0
        # There are other attributes to worry about
        return true
      else
        trace :transform_surrogate, "#{self.name} is a join table between #{pk_fks.map(&:name).inspect}"
        return false
      end
      return true
    end

    # Single-part key. It must be an Auto Counter, or we will add a surrogate

    identifying_type = irf[0].to
    if identifying_type.needs_surrogate
      trace :transform_surrogate, "#{self.name} needs a surrogate because #{irf[0].to.name} is not an AutoCounter, but #{identifying_type.supertypes_transitive.map(&:name).inspect}"
      return true
    end

    false
  end
end