schema_auto_foreign_keys
| Automatically creates foreign keys on referencing columns | Y [schema_plus_columns](https://github.com/SchemaPlus/schema_plus_columns) | Column attributes including `column.indexes` and `column.unique?` | Yschema_plus_db_default
| Use `ActiveRecord::DB_DEFAULT` to set an attribute to the database default | Yschema_plus_default_expr
| Use SQL expressions for database default values | Yschema_plus_enums
| Use enum types in migrations | Yschema_plus_foreign_keys | Extended support for foreign keys, including creation as column options, `:deferrable`, and SQLite3 support | Y [schema_plus_indexes](https://github.com/SchemaPlus/schema_plus_indexes) | Convenience and consistency in using indexes | Y [schema_plus_pg_indexes](https://github.com/SchemaPlus/schema_plus_pg_indexes) |PostgreSQL index features: `case_insenstive`, `expression` and `operator_class` | Y [schema_plus_tables](https://github.com/SchemaPlus/schema_plus_views) | Convenience and consistency in using tables | Y [schema_plus_views](https://github.com/SchemaPlus/schema_plus_views) | Create and drop views in migrations | Y [schema_validations](https://github.com/SchemaPlus/schema_validations) | Automatically defines ActiveRecord validations based on database constraints | See detailed documentation in each gem's README. *Is there some other capability you wish SchemaPlus had a gem for?* Open an issue here. Or try implementing it yourself -- creating ActiveRecord extensions is easy and fun using SchemaPlus's tools [schema_monkey](https://github.com/SchemaPlus/schema_monkey) and [schema_plus_core](https://github.com/SchemaPlus/schema_plus_core)!! ## The `schema_plus` gem The `schema_plus` gem is a wrapper that pulls in a common collection of those gems. But you can feel free to mix and match to get just the gems you want. Note: Prior to version 2.0, `schema_plus` was a single monolothic gem that implemented in itself all the features that are now included by the wrapper. > **IN PROGRESS:** In the prerelease versions of SchemaPlus 2.0, some features have yet to be migrated out to their own gems, and their code is still in the body of schema_plus. Those gems are greyed out in the list above. The documentation for their features is at the end of this README. ### Upgrading from `schema_plus` 1.8.x `schema_plus` 2.0 intends to be a completely backwards-compatible drop-in replacement for SchemaPlus 1.8.x, through restricted to ActiveRecord >= 4.2 and Ruby >= 2.1 If you find any incompatibilities, please report an issue! #### Deprecations In cases where ActiveRecord 4.2 has introduced features previously supported only by SchemaPlus, but using different names, the SchemaPlus 2.0 family of gems now issue deprecation warnings in favor of the rails form. The complete list of deprecations: * Index definition deprecates these options: * `:conditions` => `:where` * `:kind` => `:using` * `drop_table` deprecates this option: * `cascade: true` => `force: :cascade` * Foreign key definitions deprecate options to `:on_update` and `:on_delete`: * `:set_null` => `:nullify` * `add_foreign_key` and `remove_foreign_key` deprecate the method signature: * `(from_table, columns, to_table, primary_keys, options)` => `(from_table, to_table, options)` * `ForeignKeyDefinition` deprecates accessors: * `#table_name` in favor of `#from_table` * `#column_names` in favor of `Array.wrap(#column)` * `#references_column_names` in favor of `#primary_key` * `#references_table_name in favor of `#to_table` * `IndexDefinition` deprecates accessors: * `#conditions` in favor of `#where` * `#kind` in favor of `#using.to_s` ## Compatibility SchemaPlus 2.x is tested against all combinations of: * ruby **2.1.5** with activerecord **4.2**, using **mysql2**, **sqlite3** or **postgresql** ## Installation Install from http://rubygems.org via $ gem install "schema_plus" or in a Gemfile gem "schema_plus" `schema_plus` includes [schema_monkey_rails](https://github.com/SchemaPlus/schema_monkey_rails) so it will automatically be inserted in Rails apps. To use with Padrino, see [schema_monkey_padrino](https://github.com/SchemaPlus/schema_monkey_padrino) ## History * See [CHANGELOG](CHANGELOG.md) for per-version release notes. * SchemaPlus was originally derived from several "Red Hill On Rails" plugins created by [@harukizaemon](https://github.com/harukizaemon) * SchemaPlus was created in 2011 by [@mlomnicki](https://github.com/mlomnicki) and [@ronen](https://github.com/ronen) * And [lots of contributors](https://github.com/SchemaPlus/schema_plus/graphs/contributors) since then. --- --- # Prerelease: Documentation of features still be moved into separate feature gems > **NOTE** The documentation in this README is leftover from the 1.x branch; the functionality is the same, but some of the core features of schema_plus (such as foreign keys & inline index definition) are now provided by ActiveRecord 4.2. schema_plus still provides extra functionality beyond AR 4.2, but the documentation needs to be updated to be clear what's an enhancement of AR 4.2 capabilities rather than completely new features. ### Foreign Key Constraints SchemaPlus adds support for foreign key constraints. In fact, for the common convention that you name a column with suffix `_id` to indicate that it's a foreign key, SchemaPlus automatically defines the appropriate constraint. SchemaPlus also creates foreign key constraints for rails' `t.references` or `t.belongs_to`, which take the singular of the referenced table name and implicitly create the column suffixed with `_id`. You can explicitly specify whether or not to generate a foreign key constraint, and specify or override automatic options, using the `:foreign_key` keyword Here are some examples: t.integer :author_id # automatically references table 'authors', key id t.integer :parent_id # special name parent_id automatically references its own table (for tree nodes) t.integer :author_id, foreign_key: true # same as default automatic behavior t.integer :author, foreign_key: true # non-conventional column name needs to force creation, table name is assumed to be 'authors' t.integer :author_id, foreign_key: false # don't create a constraint t.integer :author_id, foreign_key: { references: :authors } # same as automatic behavior t.integer :author, foreign_key: { reference: :authors} # same default name t.integer :author_id, foreign_key: { references: [:authors, :id] } # same as automatic behavior t.integer :author_id, foreign_key: { references: :people } # override table name t.integer :author_id, foreign_key: { references: [:people, :ssn] } # override table name and key t.integer :author_id, foreign_key: { references: nil } # don't create a constraint t.integer :author_id, foreign_key: { name: "my_fk" } # override default generated constraint name t.integer :author_id, foreign_key: { on_delete: :cascade } t.integer :author_id, foreign_key: { on_update: :set_null } t.integer :author_id, foreign_key: { deferrable: true } t.integer :author_id, foreign_key: { deferrable: :initially_deferred } Of course the options can be combined, e.g. t.integer :author_id, foreign_key: { name: "my_fk", on_delete: :no_action } As a shorthand, all options except `:name` can be specified without placing them in a hash, e.g. t.integer :author_id, on_delete: :cascade t.integer :author_id, references: nil The foreign key behavior can be configured globally (see Config) or per-table (see create_table). To examine your foreign key constraints, `connection.foreign_keys` returns a list of foreign key constraints defined for a given table, and `connection.reverse_foreign_keys` returns a list of foreign key constraints that reference a given table. See doc at [SchemaPlus::ActiveRecord::ConnectionAdapters::ForeignKeyDefinition](http://rubydoc.info/gems/schema_plus/SchemaPlus/ActiveRecord/ConnectionAdapters/ForeignKeyDefinition). #### Foreign Key Issues Foreign keys can cause issues for Rails utilities that delete or load data because referential integrity imposes a sequencing requirement that those utilities may not take into consideration. Monkey-patching may be required to address some of these issues. The Wiki article [Making yaml_db work with foreign key constraints in PostgreSQL](https://github.com/SchemaPlus/schema_plus/wiki/Making-yaml_db-work-with-foreign-key-constraints-in-PostgreSQL) has some information that may be of assistance in resolving these issues. ### Tables SchemaPlus extends `create_table ... force: true` to use `:cascade` ### Column Defaults: Expressions SchemaPlus allows defaults to be set using expressions or constant values: t.datetime :seen_at, default: { expr: 'NOW()' } t.datetime :seen_at, default: { value: "2011-12-11 00:00:00" } Note that in MySQL only the TIMESTAMP column data type accepts SQL column defaults and Rails uses DATETIME, so expressions can't be used with MySQL. The standard syntax will still work as usual: t.datetime :seen_at, default: "2011-12-11 00:00:00" Also, as a convenience t.datetime :seen_at, default: :now resolves to: NOW() # PostgreSQL (DATETIME('now')) # SQLite3 invalid # MySQL If you are using Postgresql with a `json` column, the default value may be an unadorned hash. A hash having just one key `:expr` or `:value` will be taken as schema_plus syntax; i.e, these two are equivalent: t.json :fields, default: { field1: 'a', field2: 'b' } t.json :fields, default: { value: { field1: 'a', field2: 'b' } } ### Column Defaults: Using SchemaPlus introduces a constant `ActiveRecord::DB_DEFAULT` that you can use to explicitly instruct the database to use the column default value (or expression). For example: Post.create(category: ActiveRecord::DB_DEFAULT) post.update_attributes(category: ActiveRecord::DB_DEFAULT) (Without `ActiveRecord::DB_DEFAULT`, you can update a value to `NULL` but not to its default value.) Note that after updating, you would need to reload a record to replace `ActiveRecord::DB_DEFAULT` with the value assigned by the database. Note also that Sqlite3 does not support `ActiveRecord::DB_DEFAULT`; attempting to use it will raise `ActiveRecord::StatementInvalid` ### Enums (PostgreSQL only) SchemaPlus provides support for creating, altering and dropping enums. In a migration, a enum can be created: create_enum :color, :red, :green, :blue # default schema is 'public' create_enum :cmyk, :cyan, :magenta, :yellow, :black, :schema => 'color' And can be altered: (added a new value) alter_enum :color, :black alter_enum :color, :purple, :after => 'red' alter_enum :color, :pink, :before => 'purple' alter_enum :color, :white, :schema => 'public' Finally, a enum can be dropped: drop_enum :color drop_enum :cmyk, :schema => 'color' ### Schema Dump and Load (schema.rb) When dumping `schema.rb`, SchemaPlus orders the views and tables in the schema dump alphabetically, but subject to the requirement that each table or view be defined before those that depend on it. This allows all foreign key constraints to be defined within the scope of the table definition. (Unless there are cyclical dependencies, in which case some foreign keys constraints must be defined later.) Also, when dumping `schema.rb`, SchemaPlus dumps explicit foreign key definition statements rather than relying on the auto-creation behavior, for maximum clarity and for independence from global config. And correspondingly, when loading a schema, i.e. with the context of `ActiveRecord::Schema.define`, SchemaPlus ensures that auto creation of foreign key constraints is turned off regardless of the global setting. But if for some reason you are creating your schema.rb file by hand, and would like to take advantage of auto-creation of foreign key constraints, you can re-enable it: ActiveRecord::Schema.define do SchemaPlus::ForeignKeys.config.auto_create = true SchemaPlus::ForeignKeys.config.auto_index = true create_table ...etc... end