Class: MoSQL::Schema

Inherits:
Object
  • Object
show all
Includes:
Logging
Defined in:
lib/mosql/schema.rb

Instance Method Summary collapse

Methods included from Logging

#log

Constructor Details

#initialize(map) ⇒ Schema

Returns a new instance of Schema.



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# File 'lib/mosql/schema.rb', line 56

def initialize(map)
  @map = {}
  map.each do |dbname, db|
    @map[dbname] = { :meta => parse_meta(db[:meta]) }
    db.each do |cname, spec|
      next unless cname.is_a?(String)
      begin
        @map[dbname][cname] = parse_spec("#{dbname}.#{cname}", spec)
      rescue KeyError => e
        raise SchemaError.new("In spec for #{dbname}.#{cname}: #{e}")
      end
    end
  end
end

Instance Method Details

#all_columns(schema, copy = false) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 202

def all_columns(schema, copy=false)
  cols = []
  schema[:columns].each do |col|
    cols << col[:name] unless copy && !copy_column?(col)
  end
  if schema[:meta][:extra_props]
    cols << "_extra_props"
  end
  cols
end

#all_columns_for_copy(schema) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 213

def all_columns_for_copy(schema)
  all_columns(schema, true)
end

#all_mongo_dbs ⇒ Object 



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# File 'lib/mosql/schema.rb', line 258

def all_mongo_dbs
  @map.keys
end

#check_columns!(ns, spec) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 31

def check_columns!(ns, spec)
  seen = Set.new
  spec[:columns].each do |col|
    if seen.include?(col[:source])
      raise SchemaError.new("Duplicate source #{col[:source]} in column definition #{col[:name]} for #{ns}.")
    end
    seen.add(col[:source])
  end
end

#collections_for_mongo_db(db) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 262

def collections_for_mongo_db(db)
  (@map[db]||{}).keys
end

#copy_column?(col) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mosql/schema.rb', line 198

def copy_column?(col)
  col[:source] != '$timestamp'
end

#copy_data(db, ns, objs) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 217

def copy_data(db, ns, objs)
  schema = find_ns!(ns)
  db.synchronize do |pg|
    sql = "COPY \"#{schema[:meta][:table]}\" " +
      "(#{all_columns_for_copy(schema).map {|c| "\"#{c}\""}.join(",")}) FROM STDIN"
    pg.execute(sql)
    objs.each do |o|
      pg.put_copy_data(transform_to_copy(ns, o, schema) + "\n")
    end
    pg.put_copy_end
    begin
      pg.get_result.check
    rescue PGError => e
      db.send(:raise_error, e)
    end
  end
end

#create_schema(db, clobber = false) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 71

def create_schema(db, clobber=false)
  @map.values.each do |dbspec|
    dbspec.each do |n, collection|
      next unless n.is_a?(String)
      meta = collection[:meta]
      log.info("Creating table '#{meta[:table]}'...")
      db.send(clobber ? :create_table! : :create_table?, meta[:table]) do
        collection[:columns].each do |col|
          opts = {}
          if col[:source] == '$timestamp'
            opts[:default] = Sequel.function(:now)
          end
          column col[:name], col[:type], opts

          if col[:source].to_sym == :_id
            primary_key [col[:name].to_sym]
          end
        end
        if meta[:extra_props]
          column '_extra_props', 'TEXT'
        end
      end
    end
  end
end

#fetch_and_delete_dotted(obj, dotted) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 124

def fetch_and_delete_dotted(obj, dotted)
  pieces = dotted.split(".")
  breadcrumbs = []
  while pieces.length > 1
    key = pieces.shift
    breadcrumbs << [obj, key]
    obj = obj[key]
    return nil unless obj.is_a?(Hash)
  end

  val = obj.delete(pieces.first)

  breadcrumbs.reverse.each do |obj, key|
    obj.delete(key) if obj[key].empty?
  end

  val
end

#fetch_special_source(obj, source) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 143

def fetch_special_source(obj, source)
  case source
  when "$timestamp"
    Sequel.function(:now)
  else
    raise SchemaError.new("Unknown source: #{source}")
  end
end

#find_db(db) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 97

def find_db(db)
  unless @map.key?(db)
    @map[db] = @map.values.find do |spec|
      spec && spec[:meta][:alias].any? { |a| a.match(db) }
    end
  end
  @map[db]
end

#find_ns(ns) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 106

def find_ns(ns)
  db, collection = ns.split(".")
  unless spec = find_db(db)
    return nil
  end
  unless schema = spec[collection]
    log.debug("No mapping for ns: #{ns}")
    return nil
  end
  schema
end

#find_ns!(ns) ⇒ Object

Raises:



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# File 'lib/mosql/schema.rb', line 118

def find_ns!(ns)
  schema = find_ns(ns)
  raise SchemaError.new("No mapping for namespace: #{ns}") if schema.nil?
  schema
end

#parse_meta(meta) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 48

def parse_meta(meta)
  meta = {} if meta.nil?
  meta[:alias] = [] unless meta.key?(:alias)
  meta[:alias] = [meta[:alias]] unless meta[:alias].is_a?(Array)
  meta[:alias] = meta[:alias].map { |r| Regexp.new(r) }
  meta
end

#parse_spec(ns, spec) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 41

def parse_spec(ns, spec)
  out = spec.dup
  out[:columns] = to_array(spec.fetch(:columns))
  check_columns!(ns, out)
  out
end

#primary_sql_key_for_ns(ns) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 266

def primary_sql_key_for_ns(ns)
  find_ns!(ns)[:columns].find {|c| c[:source] == '_id'}[:name]
end

#quote_copy(val) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 235

def quote_copy(val)
  case val
  when nil
    "\\N"
  when true
    't'
  when false
    'f'
  when Sequel::SQL::Function
    nil
  else
    val.to_s.gsub(/([\\\t\n\r])/, '\\\\\\1')
  end
end

#table_for_ns(ns) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 254

def table_for_ns(ns)
  find_ns!(ns)[:meta][:table]
end

#to_array(lst) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 7

def to_array(lst)
  array = []
  lst.each do |ent|
    if ent.is_a?(Hash) && ent[:source].is_a?(String) && ent[:type].is_a?(String)
      # new configuration format
      array << {
        :source => ent.fetch(:source),
        :type   => ent.fetch(:type),
        :name   => (ent.keys - [:source, :type]).first,
      }
    elsif ent.is_a?(Hash) && ent.keys.length == 1 && ent.values.first.is_a?(String)
      array << {
        :source => ent.first.first,
        :name   => ent.first.first,
        :type   => ent.first.last
      }
    else
      raise SchemaError.new("Invalid ordered hash entry #{ent.inspect}")
    end

  end
  array
end

#transform(ns, obj, schema = nil) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 152

def transform(ns, obj, schema=nil)
  schema ||= find_ns!(ns)

  obj = obj.dup
  row = []
  schema[:columns].each do |col|

    source = col[:source]
    type = col[:type]

    if source.start_with?("$")
      v = fetch_special_source(obj, source)
    else
      v = fetch_and_delete_dotted(obj, source)
      case v
      when BSON::Binary, BSON::ObjectId, Symbol
        v = v.to_s
      when Hash, Array
        v = JSON.dump(v)
      end
    end
    row << v
  end

  if schema[:meta][:extra_props]
    # Kludgily delete binary blobs from _extra_props -- they may
    # contain invalid UTF-8, which to_json will not properly encode.
    extra = {}
    obj.each do |k,v|
      case v
      when BSON::Binary
        next
      when Float
        # NaN is illegal in JSON. Translate into null.
        v = nil if v.nan?
      end
      extra[k] = v
    end
    row << JSON.dump(extra)
  end

  log.debug { "Transformed: #{row.inspect}" }

  row
end

#transform_to_copy(ns, row, schema = nil) ⇒ Object 



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# File 'lib/mosql/schema.rb', line 250

def transform_to_copy(ns, row, schema=nil)
  row.map { |c| quote_copy(c) }.compact.join("\t")
end