NAME¶
Tangram::Type - mapping individual fields
DESCRIPTION¶
Tangram's persistent type system is extensible, allowing you to mount your own
types and make them persistent. All you have to do is to register your type
and provide mapping code. See Tangram::Type::Extending.
Tangram comes with built-in support for the following types:
- Simple Scalar types
- Supported are strings, integers, real numbers and dates. More types of
this ilk are easily added.
"string", "int", "real": see
Tangram::Type::Scalar
"date", "time", "datetime",
"dmdatetime": see "Date/Type/Date/DateTime" in
Tangram::Type
- Compound Structure types
- "perl_dump": see Tangram::Type::Dump::Perl. A
"perl_dump" structure may contain any structure which
Data::Dumper can dump successfully.
"storable": see Tangram::Type::Dump::Storable. Very much like
"perl_dump", but implemented via the `Storable' serialisation
engine.
"yaml": see Tangram::Type::Dump::YAML. Very much like
"perl_dump", but implemented via the `YAML' serialisation
engine. Doesn't currently work, due to inadequacies in the current Perl
YAML implementation.
NEW in Tangram 2.08:
"idbif": see Tangram::Type::Dump::Any. Like the above, but can
combine multiple object properties into a single database column.
- `Flat' Array & Hash types
- Note: these are only actually required if you need to be able to query on
individual fields inside the array/hash - otherwise, the
"perl_dump" or "idbif" mapping is a lot faster and
more flexible.
"flat_array": see "Array/Scalar" in Tangram::Type
"flat_hash": see "Hash/Scalar" in Tangram::Type
- References to other objects
- "ref": see Tangram::Type::Ref::FromMany (implementing an N to
1 relationship, in which any object can be the referant)
- Sets of other objects
- Set relationships are closest to the main type of relationship used in an
RDBMS. Avid CompSci students will know that the relational database model
is based heavily on `Set Theory', which is a subset of a more general
concept of `Categories' - generic couplings of a number of classes.
In Perl space, these collections are represented via the Set::Object module.
Sets may not have duplicate elements, and cannot contain undef
values.
"set": see Tangram::Type::Set::FromMany (implementing an
unordered N to N relationship, with all objects sharing a
common base class)
"iset": see Tangram::Type::Set::FromOne (implementing an
unordered 1 to N relationship, with all objects
sharing a common base class)
- Arrays of other objects
- The addition to Sets, you can have `Arrays' of objects, represented by a
standard Perl array in memory. Arrays may contain undef values (in
the middle of the list), and the "array" type may contain
duplicates (ie, the same element present in separate places in the list).
"array" : see Tangram::Type::Array::FromMany (implementing an
ordered N to N relationship, with all objects sharing a
common base class)
"iarray": see Tangram::Type::Array::FromOne (implementing an
ordered 1 to N relationship, with all objects sharing
a common base class)
- Hashes of other objects
- Much like the Array types, the Hash types are indexed via a string value,
and represented as a Perl hash in memory. These hashes may not contain
undef values (those are dropped). The "hash" type may
contain duplicate elements.
"hash" : see Tangram::Type::Hash::FromMany (implementing a
keyed N to N relationship, with all objects sharing a common
base class)
"ihash": see Tangram::Type::Hash::FromOne (implementing a
keyed 1 to N relationship, with all objects sharing a common
base class)