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# frozen-string-literal: true
#
# The provenance dataset extension tracks the locations of all
# dataset clones that resulted in the current dataset, and includes
# the information as a comment in the dataset's SQL. This makes it
# possible to see how a query was built, which can aid debugging.
# Example:
#
# DB[:table].
# select(:a).
# where{b > 10}.
# order(:c).
# limit(10)
# # SQL:
# # SELECT a FROM table WHERE (b > 10) ORDER BY c LIMIT 10 --
# # -- Dataset Provenance
# # -- Keys:[:from] Source:(eval at bin/sequel:257):2:in `<main>'
# # -- Keys:[:select] Source:(eval at bin/sequel:257):3:in `<main>'
# # -- Keys:[:where] Source:(eval at bin/sequel:257):4:in `<main>'
# # -- Keys:[:order] Source:(eval at bin/sequel:257):5:in `<main>'
# # -- Keys:[:limit] Source:(eval at bin/sequel:257):6:in `<main>'
#
# With the above example, the source is fairly obvious and not helpful,
# but in real applications, where datasets can be built from multiple
# files, seeing where each dataset clone was made can be helpful.
#
# The Source listed will skip locations in the Ruby standard library
# as well as Sequel itself. Other locations can be skipped by
# providing a Database :provenance_caller_ignore Regexp option:
#
# DB.opts[:provenance_caller_ignore] = /\/gems\/library_name-/
#
# Related module: Sequel::Dataset::Provenance
#
module Sequel
class Dataset
module Provenance
SEQUEL_LIB_PATH = (File.expand_path('../../..', __FILE__) + '/').freeze
RUBY_STDLIB = RbConfig::CONFIG["rubylibdir"]
INTERNAL = '<internal'
if TRUE_FREEZE
# Include provenance information when cloning datasets.
def clone(opts = nil || (return self))
super(provenance_opts(opts))
end
else
# :nocov:
def clone(opts = OPTS) # :nodoc:
super(provenance_opts(opts))
end
# :nocov:
end
%w'select insert update delete'.each do |type|
# Include the provenance information as a comment when preparing dataset SQL
define_method(:"#{type}_sql") do |*a|
sql = super(*a)
if provenance = @opts[:provenance]
comment = provenance.map do |hash|
" -- Keys:#{hash[:keys].inspect} Source:#{hash[:source]}".to_s.gsub(/\s+/, ' ')
end
comment << ""
comment.unshift " -- Dataset Provenance"
comment.unshift " -- "
comment = comment.join("\n")
if sql.frozen?
sql += comment
sql.freeze
elsif @opts[:append_sql] || @opts[:placeholder_literalizer]
sql << comment
else
sql += comment
end
end
sql
end
end
private
# Return a copy of opts with provenance information added.
def provenance_opts(opts)
provenance = {source: provenance_source, keys: opts.keys.freeze}.freeze
opts = opts.dup
opts[:provenance] = ((@opts[:provenance] || EMPTY_ARRAY).dup << provenance).freeze
opts
end
# Return the caller line for the provenance change. This skips
# Sequel itself and the standard library. Additional locations
# can be skipped using the :provenance_caller_ignore Dataset option.
def provenance_source
ignore = db.opts[:provenance_caller_ignore]
caller.find do |line|
!(line.start_with?(SEQUEL_LIB_PATH, RUBY_STDLIB, INTERNAL) ||
(ignore && line =~ ignore))
end
end
end
register_extension(:provenance, Provenance)
end
end
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