Created
May 30, 2017 20:32
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Rails task printing tables sorted by foreign key dependencies
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| namespace :db do | |
| desc "Prints tables sorted by foreign key dependencies" | |
| task fk: :environment do | |
| connection = ActiveRecord::Base.connection | |
| ignored_tables = [ActiveRecord::Base.schema_migrations_table_name, ActiveRecord::Base.internal_metadata_table_name] | |
| fs_names = connection.tables.sort - ignored_tables | |
| foreign_keys = fs_names | |
| .map { |table_name| connection.foreign_keys(table_name) }.flatten | |
| .map { |foreign_key| { 'from': foreign_key.from_table, 'to': foreign_key.to_table } }.uniq | |
| print " tables: "; p fs_names | |
| print " foreign keys: "; p foreign_keys | |
| def sort_by_dependencies(unsorted, dependencies) | |
| left = unsorted | |
| sorted = [] | |
| dependencies = dependencies.select{ |d| left.include?(d[:from]) && left.include?(d[:to]) } | |
| while !left.empty? | |
| exclude = dependencies.map{ |d| d[:from] }.uniq | |
| add = left - exclude | |
| sorted = sorted + add | |
| if add.empty? | |
| warn "Circular dependencies" | |
| return unsorted | |
| end | |
| left = left - add | |
| dependencies = dependencies.select{ |d| !add.include?(d[:to]) } | |
| end | |
| sorted | |
| end | |
| print "sorted tables: "; p sort_by_dependencies(fs_names, foreign_keys) | |
| end | |
| end |
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