I’m trying to get commands from a Rails migration file as an array based on a specific migration command, using regex. My code works well on most cases, but when there is a command with multiline code, it broke and I couldn’t fix.
Example
class AddMissingUniqueIndices < ActiveRecord::Migration
def self.up
add_index :tags, :name, unique: true
remove_index :taggings, :tag_id
remove_index :taggings, [:taggable_id, :taggable_type, :context]
add_index :taggings,
[:tag_id, :taggable_id, :taggable_type, :context, :tagger_id, :tagger_type],
unique: true, name: 'taggings_idx'
end
def self.down
remove_index :tags, :name
remove_index :taggings, name: 'taggings_idx'
add_index :taggings, :tag_id
add_index :taggings, [:taggable_id, :taggable_type, :context]
end
end
My objective is return an array with the separated commands as string. What I expect:
[
"add_index :tags, :name, unique: true",
"remove_index :taggings, :tag_id",
"remove_index :taggings, [:taggable_id, :taggable_type, :context]",
"add_index :taggings, [:tag_id, :taggable_id, :taggable_type, :context, :tagger_id, :tagger_type], unique: true, name: 'taggings_idx'"
]
First, I separe the block of change or self.up (for old migrations), and then try to use the above regex code to collect each add/remove index commands into an array:
migration_content = 'migration file in txt'
@table_name = 'taggings'
regex_pattern = /(add|remove)_indexs+:#{@table_name}.*w+:s+?w+/m
columns_to_process = migration_content.to_enum(:scan, regex_pattern).map { Regexp.last_match.to_s.squish }
puts columns_to_process
=> ["remove_index :taggings, :tag_id remove_index :taggings, [:taggable_id, :taggable_type, :context] add_index :taggings, [:tag_id, :taggable_id, :taggable_type, :context, :tagger_id, :tagger_type], unique: true"]
As you can see, didn’t work, returning just 2 commands, and both in same string.
This works fine for inline code, my problem starts when the user can use a block like the last self.up action, specially this case where has much elements, I couldn’t adapt the regex to all cases, also tried to get all content between add_index/remove_index or end, but didn’t work. Can anyone help me?
1
I think before scanning the file content you could replace all the line breaks that come after coma with space:
migration_content = migration_content.gsub(/,s*R/, ', ')
Maybe can also use gsub(/(s*R/, '(') to replace multiline function calls where the code line ends with (
This will get all the commands correctly:
@table_name = 'taggings'
commands = []
current_command = ""
inside_method = false
migration_content.each_line do |line|
stripped_line = line.strip
if stripped_line =~ /^defs+self.(up|down)/
inside_method = true
elsif stripped_line =~ /^end$/
inside_method = false
if current_command.include?(":#{@table_name}")
commands << current_command.strip unless current_command.empty?
end
current_command = ""
elsif inside_method && stripped_line =~ /^(add|remove)_index/
if current_command.include?(":#{@table_name}")
commands << current_command.strip unless current_command.empty?
end
current_command = stripped_line
elsif inside_method && !current_command.empty?
current_command += " #{stripped_line}"
end
end
if current_command.include?(":#{@table_name}")
commands << current_command.strip unless current_command.empty?
end
puts commands
Output:
["remove_index :taggings, :tag_id", "remove_index :taggings, [:taggable_id, :taggable_type, :context]", "add_index :taggings, [:tag_id, :taggable_id, :taggable_type, :context, :tagger_id, :tagger_type], unique: true, name: 'taggings_idx'", "remove_index :taggings, name: 'taggings_idx'", "add_index :taggings, :tag_id", "add_index :taggings, [:taggable_id, :taggable_type, :context]"]