X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FManual%2FCookbook.pod;h=9b9f9cefc02abe669cf426272be50dd779ac9794;hb=47d7b769c034e04989840b1efc2f5991518cff23;hp=3c080046f92a0dfec85174d5084fd2b942adeaca;hpb=70e6d5f7d5881c08702f71c6de80effc2f264ade;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Manual/Cookbook.pod b/lib/DBIx/Class/Manual/Cookbook.pod
index 3c08004..9b9f9ce 100644
--- a/lib/DBIx/Class/Manual/Cookbook.pod
+++ b/lib/DBIx/Class/Manual/Cookbook.pod
@@ -117,7 +117,12 @@ almost like you would define a regular ResultSource.
 
   __PACKAGE__->table_class('DBIx::Class::ResultSource::View');
 
-  # ->table, ->add_columns, etc.
+  # For the time being this is necessary even for virtual views
+  __PACKAGE__->table($view_name);
+
+  #
+  # ->add_columns, etc.
+  #
 
   # do not attempt to deploy() this view
   __PACKAGE__->result_source_instance->is_virtual(1);
@@ -326,10 +331,10 @@ You can write subqueries relatively easily in DBIC.
   });
 
   my $rs = $schema->resultset('CD')->search({
-    artist_id => { 'IN' => $inside_rs->get_column('id')->as_query },
+    artist_id => { -in => $inside_rs->get_column('id')->as_query },
   });
 
-The usual operators ( =, !=, IN, NOT IN, etc.) are supported.
+The usual operators ( '=', '!=', -in, -not_in, etc.) are supported.
 
 B<NOTE>: You have to explicitly use '=' when doing an equality comparison.
 The following will B<not> work:
@@ -349,8 +354,8 @@ from, select, and +select attributes.
   my $rs = $cdrs->search({
     year => {
       '=' => $cdrs->search(
-        { artist_id => { '=' => { -ident => 'me.artist_id' } } },
-        { alias => 'inner' }
+        { artist_id => { -ident => 'me.artist_id' } },
+        { alias => 'sub_query' }
       )->get_column('year')->max_rs->as_query,
     },
   });
@@ -359,11 +364,11 @@ That creates the following SQL:
 
   SELECT me.cdid, me.artist, me.title, me.year, me.genreid, me.single_track
     FROM cd me
-   WHERE year = (
-      SELECT MAX(inner.year)
-        FROM cd inner
-       WHERE artist_id = me.artist_id
-      )
+  WHERE year = (
+    SELECT MAX(sub_query.year)
+      FROM cd sub_query
+    WHERE artist_id = me.artist_id
+  )
 
 =head2 Predefined searches
 
@@ -413,44 +418,62 @@ Using SQL functions on the left hand side of a comparison is generally not a
 good idea since it requires a scan of the entire table. (Unless your RDBMS
 supports indexes on expressions - including return values of functions - and
 you create an index on the return value of the function in question.) However,
-it can be accomplished with C<DBIx::Class> when necessary.
-
-Your approach for doing so will depend on whether you have turned
-quoting on via the C<quote_char> and C<name_sep> attributes. If you
-explicitly defined C<quote_char> and C<name_sep> in your
-C<connect_info> (see L<DBIx::Class::Storage::DBI/"connect_info">) then
-you are using quoting, otherwise not.
-
-If you do not have quoting on, simply include the function in your search
-specification as you would any column:
-
-  $rs->search({ 'YEAR(date_of_birth)' => 1979 });
+it can be accomplished with C<DBIx::Class> when necessary by resorting to
+literal SQL:
 
-With quoting on, or for a more portable solution, use literal SQL values with
-placeholders:
-
-  $rs->search(\[ 'YEAR(date_of_birth) = ?', [ plain_value => 1979 ] ]);
+  $rs->search(
+    \[ 'YEAR(date_of_birth) = ?', 1979 ]
+  );
 
   # Equivalent SQL:
   # SELECT * FROM employee WHERE YEAR(date_of_birth) = ?
 
-  $rs->search({
+To include the function as part of a larger search, use the '-and' keyword
+to collect the search conditions:
+
+  $rs->search({ -and => [
     name => 'Bob',
-    -nest => \[ 'YEAR(date_of_birth) = ?', [ plain_value => 1979 ] ],
-  });
+    \[ 'YEAR(date_of_birth) = ?', 1979 ]
+  ]});
 
   # Equivalent SQL:
   # SELECT * FROM employee WHERE name = ? AND YEAR(date_of_birth) = ?
 
-Note: the C<plain_value> string in the C<< [ plain_value => 1979 ] >> part
-should be either the same as the name of the column (do this if the type of the
-return value of the function is the same as the type of the column) or
-otherwise it's essentially a dummy string currently (use C<plain_value> as a
-habit). It is used by L<DBIx::Class> to handle special column types.
+Note: the syntax for specifying the bind value's datatype and value is
+explained in L<DBIx::Class::ResultSet/DBIC BIND VALUES>.
 
 See also L<SQL::Abstract/Literal SQL with placeholders and bind values
 (subqueries)>.
 
+=head2 Software Limits
+
+When your RDBMS does not have a working SQL limit mechanism (e.g. Sybase ASE)
+and L<GenericSubQ|SQL::Abstract::Limit/GenericSubQ> is either too slow or does
+not work at all, you can try the
+L<software_limit|DBIx::Class::ResultSet/software_limit>
+L<DBIx::Class::ResultSet> attribute, which skips over records to simulate limits
+in the Perl layer.
+
+For example:
+
+  my $paged_rs = $rs->search({}, {
+    rows => 25,
+    page => 3,
+    order_by => [ 'me.last_name' ],
+    software_limit => 1,
+  });
+
+You can set it as a default for your schema by placing the following in your
+C<Schema.pm>:
+
+  __PACKAGE__->default_resultset_attributes({ software_limit => 1 });
+
+B<WARNING:> If you are dealing with large resultsets and your L<DBI> or
+ODBC/ADO driver does not have proper cursor support (i.e. it loads the whole
+resultset into memory) then this feature will be extremely slow and use huge
+amounts of memory at best, and may cause your process to run out of memory and
+cause instability on your server at worst, beware!
+
 =head1 JOINS AND PREFETCHING
 
 =head2 Using joins and prefetch
@@ -581,7 +604,7 @@ C<LinerNotes>:
   # SELECT cd.*, artist.*, liner_notes.* FROM cd
   # JOIN artist ON cd.artist = artist.id
   # JOIN liner_notes ON cd.id = liner_notes.cd
-  # WHERE artist.name = 'Bob Marley'
+  # WHERE artist.name = 'Bob Marley' AND liner_notes.notes LIKE '%some text%'
   # ORDER BY artist.name
 
 =head2 Multi-step joins
@@ -694,9 +717,9 @@ SQL statements:
 
 =head1 ROW-LEVEL OPERATIONS
 
-=head2 Retrieving a row object's Schema
+=head2 Retrieving a result object's Schema
 
-It is possible to get a Schema object from a row object like so:
+It is possible to get a Schema object from a result object like so:
 
   my $schema = $cd->result_source->schema;
   # use the schema as normal:
@@ -941,7 +964,7 @@ B<Test File> test.pl
 Alternatively you can use L<DBIx::Class::DynamicSubclass> that implements
 exactly the above functionality.
 
-=head2 Skip row object creation for faster results
+=head2 Skip result object creation for faster results
 
 DBIx::Class is not built for speed, it's built for convenience and
 ease of use, but sometimes you just need to get the data, and skip the
@@ -1040,7 +1063,7 @@ See L<DBIx::Class::ResultSetColumn> for more documentation.
 
 =head2 Creating a result set from a set of rows
 
-Sometimes you have a (set of) row objects that you want to put into a
+Sometimes you have a (set of) result objects that you want to put into a
 resultset without the need to hit the DB again. You can do that by using the
 L<set_cache|DBIx::Class::Resultset/set_cache> method:
 
@@ -1089,7 +1112,7 @@ If you want to get a filtered result set, you can just add add to $attr as follo
 
  __PACKAGE__->has_many('pages' => 'Page', 'book', { where => { scrap => 0 } } );
 
-=head2 Many-to-many relationships
+=head2 Many-to-many relationship bridges
 
 This is straightforward using L<ManyToMany|DBIx::Class::Relationship/many_to_many>:
 
@@ -1334,9 +1357,9 @@ row.
     });
   } catch {
     $exception = $_;
-  }
+  };
 
-  if ($caught) {
+  if ($exception) {
     # There was an error while handling the $job. Rollback all changes
     # since the transaction started, including the already committed
     # ('released') savepoints. There will be neither a new $job nor any
@@ -1381,14 +1404,21 @@ retry if the server goes away mid-operations, unlike C<txn_do>.
 L<DBIx::Class::Schema::Loader> will connect to a database and create a
 L<DBIx::Class::Schema> and associated sources by examining the database.
 
-The recommend way of achieving this is to use the
+The recommend way of achieving this is to use the L<dbicdump> utility or the
+L<Catalyst> helper, as described in
+L<Manual::Intro|DBIx::Class::Manual::Intro/Using DBIx::Class::Schema::Loader>.
+
+Alternatively, use the
 L<make_schema_at|DBIx::Class::Schema::Loader/make_schema_at> method:
 
   perl -MDBIx::Class::Schema::Loader=make_schema_at,dump_to_dir:./lib \
-    -e 'make_schema_at("My::Schema", { debug => 1 }, [ "dbi:Pg:dbname=foo","postgres" ])'
+    -e 'make_schema_at("My::Schema", \
+    { db_schema => 'myschema', components => ["InflateColumn::DateTime"] }, \
+    [ "dbi:Pg:dbname=foo", "username", "password" ])'
 
-This will create a tree of files rooted at C<./lib/My/Schema/> containing
-source definitions for all the tables found in the C<foo> database.
+This will create a tree of files rooted at C<./lib/My/Schema/> containing source
+definitions for all the tables found in the C<myschema> schema in the C<foo>
+database.
 
 =head2 Creating DDL SQL
 
@@ -1707,7 +1737,7 @@ methods:
     numbers => [1, 2, 3]
   });
 
-  $row->update(
+  $result->update(
     {
       numbers => [1, 2, 3]
     },
@@ -1731,8 +1761,41 @@ See L<SQL::Abstract/array_datatypes> and L<SQL::Abstract/Literal SQL with
 placeholders and bind values (subqueries)> for more explanation. Note that
 L<DBIx::Class> sets L<SQL::Abstract/bindtype> to C<columns>, so you must pass
 the bind values (the C<[1, 2, 3]> arrayref in the above example) wrapped in
-arrayrefs together with the column name, like this: C<< [column_name => value]
->>.
+arrayrefs together with the column name, like this:
+C<< [column_name => value] >>.
+
+=head2 Formatting DateTime objects in queries
+
+To ensure C<WHERE> conditions containing L<DateTime> arguments are properly
+formatted to be understood by your RDBMS, you must use the C<DateTime>
+formatter returned by L<DBIx::Class::Storage::DBI/datetime_parser> to format
+any L<DateTime> objects you pass to L<search|DBIx::Class::ResultSet/search>
+conditions. Any L<Storage|DBIx::Class::Storage> object attached to your
+L<Schema|DBIx::Class::Schema> provides a correct C<DateTime> formatter, so
+all you have to do is:
+
+  my $dtf = $schema->storage->datetime_parser;
+  my $rs = $schema->resultset('users')->search(
+    {
+      signup_date => {
+        -between => [
+          $dtf->format_datetime($dt_start),
+          $dtf->format_datetime($dt_end),
+        ],
+      }
+    },
+  );
+
+Without doing this the query will contain the simple stringification of the
+C<DateTime> object, which almost never matches the RDBMS expectations.
+
+This kludge is necessary only for conditions passed to
+L<DBIx::Class::ResultSet/search>, whereas
+L<create|DBIx::Class::ResultSet/create>,
+L<find|DBIx::Class::ResultSet/find>,
+L<DBIx::Class::Row/update> (but not L<DBIx::Class::ResultSet/update>) are all
+L<DBIx::Class::InflateColumn>-aware and will do the right thing when supplied
+an inflated C<DateTime> object.
 
 =head2 Using Unicode
 
@@ -1878,8 +1941,9 @@ just looking for this.
 For example, say that you have three columns, C<id>, C<number>, and
 C<squared>.  You would like to make changes to C<number> and have
 C<squared> be automagically set to the value of C<number> squared.
-You can accomplish this by wrapping the C<number> accessor with
-L<Class::Method::Modifiers>:
+You can accomplish this by wrapping the C<number> accessor with the C<around>
+method modifier, available through either L<Class::Method::Modifiers>,
+L<Moose|Moose::Manual::MethodModifiers> or L<Moose-like|Moo> modules):
 
   around number => sub {
     my ($orig, $self) = (shift, shift);
@@ -1889,10 +1953,10 @@ L<Class::Method::Modifiers>:
       $self->squared( $value * $value );
     }
 
-    $self->next::method(@_);
-  }
+    $self->$orig(@_);
+  };
 
-Note that the hard work is done by the call to C<next::method>, which
+Note that the hard work is done by the call to C<< $self->$orig >>, which
 redispatches your call to store_column in the superclass(es).
 
 Generally, if this is a calculation your database can easily do, try
@@ -2099,8 +2163,8 @@ L</Using joins and prefetch>.
 =item *
 
 Use L<populate|DBIx::Class::ResultSet/populate> in void context to insert data
-when you don't need the resulting L<DBIx::Class::Row> objects, if possible, but
-see the caveats.
+when you don't need the resulting L<result|DBIx::Class::Manual::ResultClass> objects,
+if possible, but see the caveats.
 
 When inserting many rows, for best results, populate a large number of rows at a
 time, but not so large that the table is locked for an unacceptably long time.