Class: Exwiw::QueryAstBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/exwiw/query_ast_builder.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(table_name, table_by_name, dump_target, logger, allow_reverse: true) ⇒ QueryAstBuilder

Returns a new instance of QueryAstBuilder.



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# File 'lib/exwiw/query_ast_builder.rb', line 11

def initialize(table_name, table_by_name, dump_target, logger, allow_reverse: true)
  @table_name = table_name
  @table_by_name = table_by_name
  @dump_target = dump_target
  @logger = logger
  @allow_reverse = allow_reverse
end

Instance Attribute Details

#dump_target ⇒ Object (readonly)

Returns the value of attribute dump_target.



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# File 'lib/exwiw/query_ast_builder.rb', line 9

def dump_target
  @dump_target
end

#table_by_name ⇒ Object (readonly)

Returns the value of attribute table_by_name.



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# File 'lib/exwiw/query_ast_builder.rb', line 9

def table_by_name
  @table_by_name
end

#table_name ⇒ Object (readonly)

Returns the value of attribute table_name.



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# File 'lib/exwiw/query_ast_builder.rb', line 9

def table_name
  @table_name
end

Class Method Details

.run(table_name, table_by_name, dump_target, logger, allow_reverse: true) ⇒ Object 



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# File 'lib/exwiw/query_ast_builder.rb', line 5

def self.run(table_name, table_by_name, dump_target, logger, allow_reverse: true)
  new(table_name, table_by_name, dump_target, logger, allow_reverse: allow_reverse).run
end

Instance Method Details

#run ⇒ Object 



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# File 'lib/exwiw/query_ast_builder.rb', line 19

def run
  table = table_by_name.fetch(table_name)

  where_clauses = build_where_clauses(table, dump_target)
  join_clauses = build_join_clauses(table, table_by_name, dump_target)

  # Reverse / "referenced_by" extraction. A table with no belongs_to path to
  # the dump target produces no where/join clauses and would otherwise dump
  # every row (see the "no relation -> dump all" case). If an extractable
  # child table references it via a foreign key (e.g. active_storage_blobs is
  # referenced by active_storage_attachments.blob_id), constrain it to just
  # the referenced ids instead. Disabled (@allow_reverse=false) while building
  # a child's subquery, so this never recurses.
  if @allow_reverse && table.name != dump_target.table_name &&
     where_clauses.empty? && join_clauses.empty?
    reverse_clause = build_referenced_by_clause(table)
    where_clauses.push(reverse_clause) if reverse_clause
  end

  QueryAst::Select.new.tap do |ast|
    ast.from(table.name)
    if table.rails_managed?
      ast.select_all!
    else
      ast.select(table.columns)
    end
    join_clauses.each { |join_clause| ast.join(join_clause) }
    where_clauses.each { |where_clause| ast.where(where_clause) }
  end
end