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Properly handle complex foreign key associations.
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The previous commit didn't properly handle the case where a table
had multiple foreign key associations (with and without cascades)
to one or more tables.

The new logic implements the following rules:

* a table which has fk cascades to more than one table must be an
  Association

* a table which has multiple fk cascades to a single table (even if it
  has fk non-cascades) is a Composition.

* a table with multiple fk cascades to a single ref table combines
  those cascades into a single Composition

* a table with fk cascades and non-cascades to a single ref table
  splits the cascades into a Composition and the non-cascades to an
  Association

Associations and Compositions are merged if possible.
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@djerius
djerius committed Aug 13, 2015
1 parent a2b09b0 commit c5b5033
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Showing 2 changed files with 195 additions and 27 deletions.
98 changes: 79 additions & 19 deletions lib/DBIx/DataModel/Schema/Generator.pm
View file
Original file line number Diff line number Diff line change
Expand Up @@ -294,27 +294,86 @@ sub perl_code {
or croak "can't generate schema: no data. "
. "Call parse_DBI() or parse_DBIx_Class() before";

# make sure there is no duplicate role on the same table

# if a table has multiple cascaded foreign keys make it part of an
# Association, not a Composition, as a table can't be part of
# multiple Compositions.
# [1] a table which has fk cascades to more than one table must be an
# Association

# [2] a table which has multiple fk cascades to a single table (even
# if it has fk non-cascades) is a Composition.

# [3] a table with multiple fk cascades to a single ref table combines
# those cascades into a single Composition

# [4] a table with fk cascades and non-cascades to a single ref table
# splits the cascades into a Composition and the non-cascades to an Association

my %seen_role;
my %relationship;
foreach my $assoc (@{$self->{assoc}}) {
my $count;
$count = ++$seen_role{$assoc->[0]{table}}{$assoc->[1]{role}};
$assoc->[1]{role} .= "_$count" if $count > 1;
$count = ++$seen_role{$assoc->[1]{table}}{$assoc->[0]{role}};
$assoc->[0]{role} .= "_$count" if $count > 1;

$relationship{ $assoc->[1]{table} }{ $assoc->[1]{is_cascade} ? 'Composition' : 'Association' }++;
my %tblassoc;
foreach my $assoc (@{$self->{assoc}}) {
my ( $t0, $t1 ) = @{ $assoc };

# separate cascades from non cascades, group by tables
# $tblassoc{t1}[is_cascade ? 0 : 1 ]{t0}[ @assocs ];
my $tassoc =
(
(
$tblassoc{ $t1->{table} } ||= [ ]
)->[ !!$t1->{is_cascade} || 0 ] ||= {}
)->{ $t0->{table} } ||= [];

push @{ $tassoc }, $assoc;
}

# an association which has more than one Composition reverts to an Association.
$_ = $_->{Association} || $_->{Composition} != 1 ? 'Association' : 'Composition'
for values %relationship;

my @relationship = ( 'Association', 'Composition' );

my @associations; # final list of associations;
my %seen_role; # ensure role names are unique;

for my $t1 ( values %tblassoc ) {

# [1]
my $cascades = $t1->[1];

if ( keys %$cascades > 1 ) {

# make them all Associations
while( my ( $t0, $assocs ) = each %{$cascades } ) {

push @{ $t1->[0]{$t0} }, @$assocs;

}

$t1->[1] = {};
}

# Merge multiple associations between two tables. Assumes that
# multiplicities are the same for the associations.

for my $ridx ( 0..1 ) {

my $rel = $t1->[$ridx];

while( my ( $t0, $assocs ) = each %{ $rel } ) {

# use the first association as a template
my $assoc = $assocs->[0];

for my $tidx ( 0..1 ) {

# combine columns
$assoc->[$tidx]->{col} = join( ' ', map { $_->[$tidx]{col} } @$assocs );

my $count = ++$seen_role{$assoc->[$tidx]->{table}}{$assoc->[1-$tidx]->{role}};
$assoc->[1-$tidx]->{role} .= "_$count" if $count > 1;
}

# add it to the final list of associations
push @associations, [ $relationship[$ridx], $assoc ];

}
}
}

# compute max length of various fields (for prettier source alignment)
my %l;
Expand Down Expand Up @@ -372,7 +431,10 @@ __END_OF_CODE__
$code .= sprintf("# $colsizes\n", qw/Class Role Mult Join/)
. sprintf("# $colsizes", qw/===== ==== ==== ====/);

foreach my $a (@{$self->{assoc}}) {
foreach my $assoc (@associations) {

my ( $relationship, $a ) = @$assoc;


# for prettier output, make sure that multiplicity "1" is first
@$a = reverse @$a if $a->[1]{mult_max} eq "1"
Expand All @@ -385,8 +447,6 @@ __END_OF_CODE__
$a->[$i]{mult} = {"0..*" => "*", "1..1" => "1"}->{$mult} || $mult;
}

my $relationship = $relationship{$a->[1]{table}};

$code .= "\n->$relationship(\n"
. sprintf($format, @{$a->[0]}{qw/table role mult col/})
. ",\n"
Expand Down
124 changes: 116 additions & 8 deletions t/v2_generator.t
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,8 @@ use warnings;

use DBIx::DataModel::Schema::Generator;

use constant NTESTS => 7;
use constant NTESTS => 17;

use Test::More tests => NTESTS;


Expand Down Expand Up @@ -45,6 +46,26 @@ SKIP: {
emp_id INTEGER NOT NULL REFERENCES employee(emp_id),
status_name TEXT
);
-- two foreign keys to one reftable, one cascades
CREATE TABLE fk_reftable_1 (
emp_id_status INTEGER NOT NULL REFERENCES employee_status(emp_id_status),
emp_id INTEGER NOT NULL REFERENCES employee_status(emp_id) ON DELETE CASCADE
);
-- two foreign keys to one reftable, both cascade
CREATE TABLE fk_reftable_2 (
emp_id_status INTEGER NOT NULL REFERENCES employee_status(emp_id_status) ON DELETE CASCADE,
emp_id INTEGER NOT NULL REFERENCES employee_status(emp_id) ON DELETE CASCADE
);
-- two foreign keys to two reftables, both cascade
CREATE TABLE fk_reftable_3 (
emp_id_status INTEGER NOT NULL REFERENCES employee_status(emp_id_status) ON DELETE CASCADE,
emp_id INTEGER NOT NULL REFERENCES employee(emp_id) ON DELETE CASCADE
);
});

my $generator = DBIx::DataModel::Schema::Generator->new(
Expand All @@ -54,11 +75,98 @@ SKIP: {
$generator->parse_DBI($dbh);
my $perl_code = $generator->perl_code;

like($perl_code, qr{Table\(qw/Activity}, "Table Activity");
like($perl_code, qr{Table\(qw/ActivityEvent}, "Table ActivityEvent");
like($perl_code, qr{Composition.*?activity_events}s, "Composition");
like($perl_code, qr{Association.*?activit(ie|y)s}s, "Association");
like($perl_code, qr{employee_2}s, "avoid duplicate associations");
sub match_entry {

# $type, [ $class, @etc ], [ ... ], $msg
my $msg = pop;
my $type = quotemeta(shift);

# match start and end of an line, depends if there are one or two lines per entry
my ( $start, $end ) = ( @_ > 1) ? ( qr{\[qw/\s*}, qr{\s*/\]} ) : ( qr{qw/\s*}, qr{\s*/} ) ;

my $re = join('',
qr{$type\s*\(\s*},
join( qr{\s*,\s*}, # join multiple lines
map {
join( '',
$start,
join( qr/\s+/,
map { defined($_) ? quotemeta( $_ ) # so multiplicity of '*' passes through
: qr{[^)]*?} # undef means match to end of line (matches any char except right paren)
} @{$_},
),
$end,
)
} @_ # iterate over lines
),
);


like( $perl_code, qr/$re/, $msg );
}

# ensure Tables are created
match_entry( 'Table', [ $_, undef ], "created Table $_" )
foreach qw[ Activity ActivityEvent Department Employee EmployeeStatus FkReftable1 ];

match_entry( 'Association',
[ qw( Employee employee 1 emp_id emp_id ) ],
[ qw( Activity activities * supervisor emp_id ) ],
'Merged Association',
);


match_entry( 'Association',
[ qw( Department department 1 dpt_id ) ],
[ qw( Activity activities * dpt_id ) ],
'Association: Department, Activity',
);


match_entry( 'Composition',
[ qw( Activity activity 1 act_id ) ],
[ qw( ActivityEvent activity_events * act_id ) ],
'Composition Activity, ActivityEvent'
);

match_entry( 'Association',
[ qw( Employee employee 1 emp_id ) ],
[ qw( EmployeeStatus employee_statuses * emp_id ) ],
'Association: Employee, EmployeeStatus',
);

match_entry( 'Association',
[ qw( EmployeeStatus employee_status 1 emp_id_status ) ],
[ qw( FkReftable1 fk_reftable_1s * emp_id_status ) ],
'Association: two foreign keys to one reftable, one cascades',
);

# checks for duplicate role as well.
match_entry( 'Composition',
[ qw( EmployeeStatus employee_status_2 1 emp_id ) ],
[ qw( FkReftable1 fk_reftable_1s_2 * emp_id ) ],
'Composition: two foreign keys to one reftable, one cascades',
);

match_entry( 'Composition',
[ qw( EmployeeStatus employee_status 1 emp_id emp_id_status ) ],
[ qw( FkReftable2 fk_reftable_2s * emp_id emp_id_status ) ],
'Merged Composition: two foreign keys to one reftable, both cascade',
);

match_entry( 'Association',
[ qw( EmployeeStatus employee_status 1 emp_id_status ) ],
[ qw( FkReftable3 fk_reftable_3s * emp_id_status ) ],
'Forced Association: two foreign keys to two reftables, both cascade (1)',
);


match_entry( 'Association',
[ qw( Employee employee 1 emp_id ) ],
[ qw( FkReftable3 fk_reftable_3s * emp_id ) ],
'Forced Association: two foreign keys to two reftables, both cascade (2)',
);


# diag($perl_code);

Expand All @@ -78,8 +186,8 @@ SKIP: {
);
$generator->parse_DBI($dbh);
$perl_code = $generator->perl_code;
like($perl_code, qr{Table\(qw/Foo}, "Table foo");
like($perl_code, qr{Table\(qw/Bar}, "Table bar");
like($perl_code, qr{Table\(qw/Foo}, "created Table foo");
like($perl_code, qr{Table\(qw/Bar}, "created Table bar");
}


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