alzabo::faq(3pm) [debian man page]
Alzabo::FAQ(3pm) User Contributed Perl Documentation Alzabo::FAQ(3pm) NAME
Alzabo::FAQ - Frequently Asked Questions How can I generate the SQL to turn one schema into another? Assuming you have schema objects representing these already created (through reverse engineering for example) and both schemas are for the same RDBMS, you can simply do this: my @sql = $schema1->rules->schema_diff( old => $schema1, new => $schema2 ); The @sql array will contain all the SQL statements necessary to transform the schema in $schema1 into the schema in $schema2. If you want to sync a schema object to the current state of the RDBMS backend's schema, check out the "Alzabo::Create::Schema->sync_back- end" method. How can I make a local copy of the documentation as HTML? Alzabo comes with a script called "make_html_docs.pl". It takes three arguments. The first is the source file directory root. The second is the target directory. The last is the absolute URL path that this target directory represents. If you have perl 5.6.0 or greated installed, it is recommended that you use it to run this script as the Pod::Html module included with more recent Perls does a much better job of making HTML. If you were in the root of the source directory you might run this as: perl ./make_html_docs.pl ./lib /usr/local/apache/htdocs/Alzabo_docs /Alzabo_docs The script will create an index.html file as well as turning the documentation into HTML. How can I optimize memory usage under mod_perl? You should simply preload the Alzabo::Runtime module (which loads all the other modules it needs). In addition, if you are using Alzabo::MethodMaker, make sure it runs in the parent. This module can create a lot of methods on the fly and each method eats up some memory. Finally, you can preload one or more schema objects. The easiest way to do this is to simply pass its name to Alzabo::Runtime when you use it, like this: use Alzabo::Runtime qw( schema1 schema2 ); How can I get objects for tables linked via the Mason GUI? For example, if I have a websites2categories table which maps a list of categories that a given web site should display -- and uses website_id and category_id in a 1..n relationship -- what is the proper way to set that up in the GUI and then in my code? In the GUI, you can simply create a relationship from websites to categories, and declare it n..n. Alzabo will automatically create a ta- ble called websites_categories, and you're free to change the name to whatever you want. Then if you use "Alzabo::MethodMaker", Alzabo will see that you have a table with 2 cols, both of which are part of the PK, and that it has 1..n relationships with 2 other tables, and it will create the appropriate methods. You can see what methods are being created by setting the "ALZABO_DEBUG" environment variable to "METHODMAKER" before loading Alz- abo::MethodMaker. It'll spit everything out to STDERR. There's also the generated documentation, which is available via the "docs_as_pod()" schema method after MethodMaker does its thing. AUTHOR
Dave Rolsky, <autarch@urth.org> perl v5.8.8 2007-12-23 Alzabo::FAQ(3pm)
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Alzabo::QuickRef(3pm) User Contributed Perl Documentation Alzabo::QuickRef(3pm) NAME
Alzabo::QuickRef - A quick reference to methods in the Alzabo classes GENERAL
This reference is intended to provide a quick reference to some of the more commonly used methods that Alzabo provides. In addition, this reference can give you an idea of what classes contain certain types of methods, so you have an idea of where to look in order to figure out how to achieve a certain task. Alzabo, Alzabo::Create, and Alzabo::Runtime These modules are mostly used just to load other modules. The "Alzabo::Runtime" module can be used to preload schemas at compile time by doing: use Alzabo::Runtime qw( schema1 schema2 schema3 ); Alzabo::MethodMaker This module can be used to generate many useful convenience methods. This is done by auto-generating methods in new packages and re-bless- ing some of the schema objects into these packages. To have it generate all the possible methods for a schema you would do: use Alzabo::MethodMaker ( schema => 'some_schema', # Root for new packages class_root => 'My::Data', # Make all possible methods all => 1 ); This will make convenience methods for such things as getting table and column objects, following various types of foreign keys, and get- ting data from row objects. METHODS
Retrieving data Alzabo::Runtime::Schema This object allows you to connect to the database. It contains several data retrieval methods including "join". * load_from_file Load an existing schema object from disk. Returns a new schema object. * set_user ($user) Set the username to be used when connecting to the database. * set_password ($password) Set the password to be used when connecting to the database. * set_host ($host) Set the host to be used when connecting to the database. * connect (%params) Connect to the RDBMS. This will use the previously set username/password/host, though these can be overridden by the %params given to the call. Important: This method must be called before any data retrieval is attempted. * join Fetch rows from one or more tables based on a table join. Returns either a "Alzabo::Runtime::RowCursor" or "Alzabo::Runtime::JoinCur- sor" object. * function/select Allows you to execute arbitrary column aggregate SQL functions such as "AVG" or "MAX" with a multi-table join. * table ($name) Returns an "Alzabo::Runtime::Table" object. This is important because most of the row fetching operations are table object methods. Alzabo::Runtime::Table Objects in this class have methods allowing you to insert new rows as well as retrieving exist data in the form of "Alzabo::Runtime::Row" or "Alzabo::Runtime::RowCursor" objects. All methods that return a single row return an "Alzabo::Runtime::Row" object. All methods that return multiple rows return an "Alzabo::Runtime::RowCursor" object. All methods that return rows can be given the "no_cache" parameter, which ensures that the row(s) returned will not be cached. Rows obtained in this manner should not be updated or deleted, as this will play havoc with the caching system. See the "Alzabo::Runtime::Row" documentation for more details. All methods that return multiple rows in the form of a cursor object can take an "order_by" parameter. See the "Alzabo::Runtime::Table" documentation for more details. * insert Insert a new row and return it. * row_by_pk Returns the row identified by the primary key give. * rows_where Retrieves a set of rows based on a where clause. Please see the method documentation for details on how where clauses are constructed. * all_rows Retrieves all the rows in the table. * function/select Allows you to execute arbitrary column aggregate SQL functions such as "AVG" or "MAX". * potential_row Make a new "Alzabo::Runtime::Row" in the "potential" state. Alzabo::Runtime::Row Objects in this class represent a single row of data. You can retrieve the actual column values from it, update it, or delete it. * select (@list_of_column_names) Given a list of column names, this method returns the values for those columns. * update (%hash_of_columns_and_values) Given a hash of columns and values, this method will update the database and the object to match those values. * delete Deletes the row from the database. Further attempts to retrieve data from this row will throw an exception. * rows_by_foreign_key Given a foreign key object from the row's table to another table, returns either an "Alzabo::Runtime::Row" object or an "Alzabo::Run- time::RowCursor" object for the row(s) in the table to which the relationship exists, based on the value of the relevant column(s) in the current row. This method can also take a "no_cache" and/or "order_by" parameter. Alzabo::Runtime::RowCursor Objects in this class are used to return multiple rows as a cursor, rather than as a list. This is much more efficient, at the expense of a few extra lines in your code. * next Returns the next "Alzabo::Runtime::Row" object, or undef if there are no more. * all_rows Returns a list of all the remaining "Alzabo::Runtime::Row" objects, or an empty list if there are no more. Creating/removing a schema Alzabo::Create::Schema This object represents a schema, and contains one or more table objects. It is only used when creating or altering a schema, as opposed to when fetching data. Data manipulation is done via the "Alzabo::Runtime::*" classes. * reverse_engineer Connect to a database and reverse engineer a schema. Returns a new schema object. * load_from_file Load an existing schema object from disk. Returns a new schema object. * create If the schema has not yet been instantiated in an RDBMS, this method will instantiate the schema. If it has been previously instanti- ated, it will bring the schema in the RDBMS into sync with its object representation (altering tables/columns, etc.) Where possible, exist data will be preserved. * make_sql Returns an array, each element of which is a SQL statement. The SQL is either the SQL to create the schema from scratch or the SQL needed to update the RDBMS to match the current object. See the "create" method for more details. * drop Drop the database from the RDBMS where it was created. Does not remove the schema object itself from disk. * delete Delete the schema object files from disk. Does not drop the database from the RDBMS. AUTHOR
Dave Rolsky, <autarch@urth.org> perl v5.8.8 2007-12-23 Alzabo::QuickRef(3pm)