Class: EmptyEye::ShardCollection

Inherits:
Object
  • Object
show all
Defined in:
lib/empty_eye/shard_collection.rb

Instance Method Summary collapse

Constructor Details

#initialize(primary_shard_klass) ⇒ ShardCollection

a collection of all the view_shards these are wranglers for the shards uses ‘array’ as a proxy performs array methods by passing things off in method missing



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# File 'lib/empty_eye/shard_collection.rb', line 9

def initialize(primary_shard_klass)
  @master_class = primary_shard_klass.master_class
  @primary = PrimaryShard.new(primary_shard_klass)
  @array = [@primary]
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(m, *args, &block) ⇒ Object

delegate to the array proxy when the method is missing



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# File 'lib/empty_eye/shard_collection.rb', line 77

def method_missing(m, *args, &block)
  if respond_to?(m)
    array.send(m, *args, &block)
  else
    super
  end
end

Instance Method Details

#array ⇒ Object

the proxy object for instances



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# File 'lib/empty_eye/shard_collection.rb', line 16

def array
  @array
end

#create_view_sql ⇒ Object

generates view sql



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# File 'lib/empty_eye/shard_collection.rb', line 90

def create_view_sql
  #determine what shard will handle what columns
  map_attribute_management
  #start with primary table
  query = primary_arel_table
  
  #build select clause with correct table handling the appropriate columns
  query = query.project(*arel_columns)
  
  #build joins
  each do |shard|
    next if shard.primary
    current = shard.arel_table
    key = shard.foreign_key.to_sym
    if shard.type_column
      query.join(current).on(
        primary.key.eq(current[key]), shard.type_column.eq(shard.type_value)
      )
    else
      query.join(current).on(
        primary.key.eq(current[key])
      )
    end
  end
  
  #we dont need to keep this data
  free_arel_columns
  
  #STI condition if needed
  if primary.sti_also?
    query.where(primary.type_column.eq(primary.type_value))
  end
  
  #build view creation statement
  @view_sql = "CREATE VIEW #{primary.klass.compute_view_name} AS\n#{query.to_sql}"
end

#create_with(assoc) ⇒ Object

add shard based on association from master_class



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# File 'lib/empty_eye/shard_collection.rb', line 36

def create_with(assoc)
  new_shard = Shard.new(assoc)
  reject! {|shard| shard.name == new_shard.name}
  push(new_shard)
  new_shard
end

#delegate_map(name, hash) ⇒ Object

takes the name of shard and a hash of intended updates from master instance returns a subset of hash with only values the shard handles



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# File 'lib/empty_eye/shard_collection.rb', line 49

def delegate_map(name, hash)
  keys = update_mapping[name] & hash.keys
  keys.inject({}) do |res, col|
    res[col] = hash[col] if hash[col]
    res
  end
end

#descend(klass) ⇒ Object 



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# File 'lib/empty_eye/shard_collection.rb', line 30

def descend(klass)
  @master_class = klass
  self
end

#inspect ⇒ Object

we want to see the proxy object not the class info



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# File 'lib/empty_eye/shard_collection.rb', line 21

def inspect
  array.inspect
end

#klasses ⇒ Object

array of shard classes



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# File 'lib/empty_eye/shard_collection.rb', line 63

def klasses
  map(&:klass)
end

#master_class ⇒ Object

the class to which the shards belongs



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# File 'lib/empty_eye/shard_collection.rb', line 26

def master_class
  @master_class
end

#names ⇒ Object 



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# File 'lib/empty_eye/shard_collection.rb', line 67

def names
  map(&:name)
end

#primary ⇒ Object

the primary shard



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# File 'lib/empty_eye/shard_collection.rb', line 58

def primary
  @primary
end

#respond_to?(m) ⇒ Boolean

this object responds to array methods

Returns:

  • (Boolean) 


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# File 'lib/empty_eye/shard_collection.rb', line 72

def respond_to?(m)
  super || array.respond_to?(m)
end

#schema_version ⇒ Object 



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# File 'lib/empty_eye/shard_collection.rb', line 43

def schema_version
  @schema_version
end

#view_sql ⇒ Object 



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# File 'lib/empty_eye/shard_collection.rb', line 85

def view_sql
  @view_sql
end