--- name: "Rose::DB::Object::Metadata::Relationship::OneToMany" section: "3pm" platform: "linux" package: "librose-db-object-perl" version: "1:0.820-2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/Rose::DB::Object::Metadata::Relationship::OneToMany" --- # Rose::DB::Object::Metadata::Relationship::OneToMany(3pm) One to many table relationship metadata object. ## NAME Rose::DB::Object::Metadata::Relationship::OneToMany - One to many table relationship metadata object. ## SYNOPSIS ``` use Rose::DB::Object::Metadata::Relationship::OneToMany; $rel = Rose::DB::Object::Metadata::Relationship::OneToMany->new(...); $rel->make_methods(...); ... ``` ## DESCRIPTION Objects of this class store and manipulate metadata for relationships in which a single row from one table refers to multiple rows in another table. This class inherits from Rose::DB::Object::Metadata::Relationship. Inherited methods that are not overridden will not be documented a second time here. See the Rose::DB::Object::Metadata::Relationship documentation for more information. ## METHOD MAP - "count" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'count'"` ... - "find" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'find'"` ... - "iterator" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'iterator'"` ... - "get\_set" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'get_set'"` ... - "get\_set\_now" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'get_set_now'"` ... - "get\_set\_on\_save" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'get_set_on_save'"` ... - "add\_now" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'add_now'"` ... - "add\_on\_save" Rose::DB::Object::MakeMethods::Generic, objects\_by\_key, `"interface => 'add_on_save'"` ... See the Rose::DB::Object::Metadata::Relationship documentation for an explanation of this method map. ## CLASS METHODS - **default\_auto\_method\_types \[TYPES\]** Get or set the default list of auto\_method\_types. TYPES should be a list of relationship method types. Returns the list of default relationship method types (in list context) or a reference to an array of the default relationship method types (in scalar context). The default list contains "find", "get\_set\_on\_save", and "add\_on\_save". ## OBJECT METHODS - **build\_method\_name\_for\_type TYPE** Return a method name for the relationship method type TYPE. For the method types "get\_set", "get\_set\_now", and "get\_set\_on\_save", the relationship's name is returned. For the method types "add\_now" and "add\_on\_save", the relationship's name prefixed with "add\_" is returned. For the method type "find", the relationship's name prefixed with "find\_" is returned. For the method type "count", the relationship's name suffixed with "\_count" is returned. For the method type "iterator", the relationship's name suffixed with "\_iterator" is returned. Otherwise, undef is returned. - **is\_singular** Returns false. - **manager\_class \[CLASS\]** Get or set the name of the Rose::DB::Object::Manager-derived class used to fetch objects. The make\_methods method will use Rose::DB::Object::Manager if this value is left undefined. **Note:** when the name of a relationship that has `"manager_args"` is used in a Rose::DB::Object::Manager with\_objects or require\_objects parameter value, *only* the sort\_by argument will be copied from `"manager_args"` and incorporated into the query. - **manager\_method \[METHOD\]** Get or set the name of the manager\_class class method to call when fetching objects. The make\_methods method will use get\_objects if this value is left undefined. - **manager\_count\_method \[METHOD\]** Get or set the name of the manager\_class class method to call when counting objects. The make\_methods method will use get\_objects\_count if this value is left undefined. - **manager\_iterator\_method \[METHOD\]** Get or set the name of the manager\_class class method to call when creating an iterator. The make\_methods method will use get\_objects\_iterator if this value is left undefined. - **manager\_args \[HASHREF\]** Get or set a reference to a hash of name/value arguments to pass to the manager\_method when fetching objects. For example, this can be used to enforce a particular sort order for objects fetched via this relationship. For example: ``` Product->meta->add_relationship ( code_names => { type => 'one to many', class => 'CodeName', column_map => { id => 'product_id' }, manager_args => { sort_by => CodeName->meta->table . '.name', }, }, ); ``` This would ensure that a `"Product"`'s `"code_names()"` are listed in alphabetical order. Note that the "name" column is prefixed by the name of the table fronted by the `"CodeName"` class. This is important because several tables may have a column named "name." If this relationship is used to form a JOIN in a query along with one of those tables, then the "name" column will be ambiguous. Adding a table name prefix disambiguates the column name. Also note that the table name is not hard-coded. Instead, it is fetched from the Rose::DB::Object-derived class that fronts the table. This is more verbose, but is a much better choice than including the literal table name when it comes to long-term maintenance of the code. See the documentation for Rose::DB::Object::Manager's get\_objects method for a full list of valid arguments for use with the `"manager_args"` parameter, but remember that you can define your own custom manager\_class and thus can also define what kinds of arguments `"manager_args"` will accept. - **map\_column LOCAL \[, FOREIGN\]** If passed a local column name LOCAL, return the corresponding column name in the foreign table. If passed both a local column name LOCAL and a foreign column name FOREIGN, set the local/foreign mapping and return the foreign column name. - **column\_map \[HASH \| HASHREF\]** Get or set a reference to a hash that maps local column names to foreign column names. - **query\_args \[ARRAYREF\]** Get or set a reference to an array of query arguments to add to the query passed to the manager\_method when fetching objects. - **type** Returns "one to many". ## AUTHOR John C. Siracusa (siracusa@gmail.com) ## LICENSE Copyright (c) 2010 by John C. Siracusa. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.