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Fry-Lib-CDBI-Basic-0.15
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/ Fry::Lib::CDBI::Basic

NAME

Fry::Lib::CDBI::Basic - A basic library of Class::DBI functions for use with Fry::Shell.

VERSION

This document describes version 0.14.

DESCRIPTION

This module contain wrappers around Class::DBI methods for common database functions such as creating,deleting,inserting and updating records. There are also some basic functions to enable and view DBI::Profile logs.

COMMANDS

        Search
                *search_abstract
                *cdbi_search
                *cdbi_search_like
                *cdbi_search_regex
        Search based
                cdbi_delete
                *cdbi_update
                *verify_no_delim
                *replace
                cdbi_find_or_create
        Menu based
                cdbi_delete_obj
                cdbi_update_obj
                verify_no_delim_obj
        Debugging via DBI::Profile
                set_dbi_log_level       
                print_dbi_log
                clear_dbi_log
        Other
                cdbi_create
                cdbi_multi_insert
                display_table_list
                print_columns

        Note: Any command with a * is affected by the variable action_columns

Search Commands

These commands search and give back Class::DBI objects.

        cdbi_search(@search_term): wrapper around &Class::DBI::search
        cdbi_search_like(@search_term): wrapper around &Class::DBI::search_like
        cdbi_search_regex(@search_term): does regular expression searches (ie REGEXP for Mysql or ~ for Postgresql)
        search_abstract(@search_term): wrapper around Class::DBI::AbstractSearch::search_where,
                by default does regular expression searches, change this via
                $cls->Var('abstract_opts')->{cmp}

These commands have a common input format that supports searching a column by a value. A column constraint is in the regular expression form:

        $column$splitter$operator?$column_value

The above form will be represented by $search_term in any argument descriptions of functions. $splitter is controlled by the splitter variable. $operator is only used by &search_abstract and has the possible values:

        > :  greater than
        >= : greater than or equal to
        < : less than
        <= : less than or equal to
        = : equal to
        != : not equal to

Like Class::DBI's search method, multiple column constraints are anded together. To specify multiple column constraints, separate them with white space.

Examples:

Using &search, the input 'hero=superman weakness=kryptonite' translates to (hero=>'superman',weakness=>'kryptonite') being passed to &search and the sql where part being: WHERE hero = 'superman' AND weakness = 'kryptonite'

Using &search_abstract, the input 'id=>41 module=Class::DBI' translates to the sql where part being: WHERE id >= 41 AND module ~ 'Class::DBI'.

Note: To set the columns and tables for a query look at OPTIONS under Fry::Lib::CDBI::Load.

Search based Commands

These commands get the results of a search and then do something with it. The variable cdbi_search contains the search command called for any of these functions. This variable is found in other CDBI libraries and is also an option for easily changing search types.

        cdbi_delete(@search_term): deletes result objects
        cdbi_update(@search_term): result objects printed to a file, user changes file and objects updated

                This function contains two flags, safe_update and only_modified. By
                default, both flags are set. The safe_update flag calls &verify_no_delim_obj to
                verify none of the results contain a display delimiter. If any are found, the command exits
                early. For many records, this may be slow, in which case run
                &verify_no_delim on all the objects once and then turn off the flag.
                The only_modified flag modifies the command to only call &update on
                objects that have been changed. With the flag off, &update would be called
                on all objects. If you don't mind this and want to speed up the update,
                then you can turn off the flag.

        replace(@search_term,$perl_operation): evaluates a perl operation on each column value of the results,
        treating each value as $_
                        
                For example if one result row had the following values:
                '4','many','amazing','some bold punk' 
                and you did the perl operation 's/o/a/g', the result row would be
                converted to:
                '4','many','amazing','same bald punk' 

                note: Since $operation is distinguished from @search_terms by a
                white space, $operation can't contain any white space.

        verify_no_delim(@search_term): Verifies that result objects do not contain the display
                delimiter.  Since this delimiter can be used to separate fields in a
                file, having them in the data could result in incorrect parsing. The
                delimiter is specified by the variable field_delimiter

        cdbi_find_or_create(@search_term): If no result objects found then one is created
 cdbi_delete_obj(@cdbi): same functionality as cdbi_delete
 cdbi_update_obj(@cdbi): same functionality as cdbi_update
 verify_no_delim_obj(@cdbi): same functionality as verify_no_delim

The three menu commands take Class::DBI row objects as input. The only way to currently enter objects as input is via the menu option. To use these commands, first execute a search command with the -m option

        `-m search_abstract tags=goofy`

Then execute one of the menu based commands with numbers specifying which objects you choose from the numbered menu.

        `cdbi_delete_obj 1-4,8-10`

Why not just use the corresponding search based command? You'd use a menu based command when you want to pick only certain results and perform actions on them.

Debugging via DBI::Profile.

There are three commands that wrap around DBI::Profile that manage benchmark data useful in debugging DBI statements, set_dbi_log_level, print_dbi_log and clear_dbi_log. These commands respectively set the log level (which is between -15 and 15), print the current log, and clear the log. To enable debugging, you must first set a log level via &set_dbi_log_level. See DBI::Profile for more details.

Other Commands

        cdbi_create(($value$delim)+): wrapper around &Class::DBI::create. &cdbi_create uses
                &aliasInsert to parse the input into values for the table's columns. The
                columns which map to the parsed values are defined via the variable insert_columns.
                Ie if @insert_columns = ('car','year') and the insert delimiter is ',,' and your
                input is 'chevy,,57' then &create will create a record with car='chevy' and
                year='57'

                note: records with multi-line data can't be inserted this way 

        cdbi_multi_insert($file): same input format as &cdbi_create,reads several lines from
                file and inserts them as new records
        display_table_list(): lists tables in the database
        print_columns(): prints the current table's columns

Library Variables

        editor: sets the editor used by &cdbi_update
        splitter: separates column from its value in arguments of search-based functions and used
                for &Class::DBI::AbstractSearch::search_where searches  
        abstract_opts: optional parameters passed to &Class::DBI:AbstractSearch::search_where
        delim: hash with the following keys:
                display: delimits column values when editing records in file with &cdbi_update
                insert: delimits values when using &cdbi_insert
                tag: delimits values used in CDBI::Tags library.
        insert_columns(\@): implicit order of columns for

Miscellaneous

Input Aliasing

If there are queries you do often then you can alias them to an even shorter command via &aliasInput. The default &aliasInput aliases 'a' to returning all rows of a table and replaces anything matching /c\d/ with the corresponding column.

Changing Output Format

Via the subhook viewsub, it's possible to choose your own subroutine to format your output. By default all search results are displayed using &View::CLI::objAoH. If you want an aligned output similar to most database shells, use &printTextTable ie (-v=tt s id=48).

Writing Class::DBI Libraries

Make sure you've read Fry::Shell's 'Writing Libraries' section.

When writing a Class::DBI library:

        1. Define 'CDBI::Load' as dependent module in your &_default_data.
        2. Refer to Fry::Lib::CDBI::Load for a list of core Class::DBI global data
        to use in your functions.

I encourage not only wrapper libraries around Class::DBI::* modules but any DBI modules. Even libraries that use tables of a specific schema are welcome (see Fry::Lib::CDBI::Tags).

Suggested Modules

Three functions are dependent on external modules. Since their require statements are wrapped in an eval, the functions fail safely if not found.

        &cdbi_update: File::Temp
        &search_abstract: Class::DBI::AbstractSearch
        &print_text_table: Text::Reform

See Also

Fry::Shell, Class::DBI

TO DO

 -port old TESTS!
 -defining relations between tables with has_*
 -provide direct SQL queries
 -support shell-like parsing of quotes to allow spaces in queries
 -specify sorting and limit of queries
 -embed sql or database functions in queries
 -create an easily-parsable syntax for piecing chunks into 'or' and 'and' parts
        to be passed to Class::DBI::AbstractSearch

Thanks

I give a shot out to Kwan for encouraging me to check out Postgresql and Perl when my ideas of a database shell were simply bash and a text file.

A shot out also to Jeff Bisbee for pointing me to Class::DBI when I was pretty naive in the perl world.

AUTHOR

Me. Gabriel that is. I welcome feedback and bug reports to cldwalker AT chwhat DOT com . If you like using perl,linux,vim and databases to make your life easier (not lazier ;) check out my website at www.chwhat.com.

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.