This HasMany<OtherRecord> represents a simple one-to-many relationship between two records. More...

#include <HasMany.hpp>

Public Types
using	ReferencedRecord = OtherRecord
	The record type of the "many" side of the relationship.

using	ReferencedRecordList = std::vector< std::shared_ptr< OtherRecord > >
	The list of records on the "many" side of the relationship.

using	value_type = OtherRecord
	Record type of the "many" side of the relationship.

using	iterator = ReferencedRecordList::iterator
	Iterator type for the list of records.

using	const_iterator = ReferencedRecordList::const_iterator
	Const iterator type for the list of records.

Public Member Functions
ReferencedRecordList const &	All () const
	Retrieves the list of loaded records.

ReferencedRecordList &	All ()
	Retrieves the list of records as mutable reference.

template<typename Callable >
void	Each (Callable const &callable)
	Iterates over the list of records and calls the given callable for each record.

ReferencedRecordList &	Emplace (ReferencedRecordList &&records) noexcept
	Emplaces the given list of records.

ReferencedRecordList *	LoadedRecords () noexcept
	Returns the already-loaded records, or `nullptr` when the relation is not loaded.

std::size_t	Count () const noexcept
	Retrieves the number of records in this 1-to-many relationship.

bool	IsEmpty () const noexcept
	Checks if this 1-to-many relationship is empty.

OtherRecord const &	At (std::size_t index) const
	Retrieves the record at the given index.

OtherRecord &	At (std::size_t index)
	Retrieves the record at the given index.

OtherRecord const &	operator[] (std::size_t index) const
	Retrieves the record at the given index.

OtherRecord &	operator[] (std::size_t index)
	Retrieves the record at the given index.

iterator	begin ()

iterator	end ()

const_iterator	begin () const

const_iterator	end () const

constexpr std::weak_ordering	operator<=> (HasMany const &other) const noexcept=default
	Three-way comparison operator.

constexpr bool	operator== (HasMany const &other) const noexcept=default
	Equality comparison operator.

constexpr bool	operator!= (HasMany const &other) const noexcept=default
	Inequality comparison operator.

void	SetAutoLoader (Loader loader) noexcept
	Used internally to configure on-demand loading of the records.

Static Public Attributes
static constexpr auto	InverseSelector = TheInverseSelector
	Singles out the foreign key of `OtherRecord` that backs this relationship.

Detailed Description

template<typename OtherRecord, auto TheInverseSelector = AutoDetectRelation>
class Lightweight::HasMany< OtherRecord, TheInverseSelector >

This HasMany<OtherRecord> represents a simple one-to-many relationship between two records.

The HasMany<OtherRecord> is a member of the "one" side of the relationship.

OtherRecord must declare a BelongsTo member that points back to this "one" side. That member is located by matching the relationship type, not by its position in either record, so the two relationship members may be declared at any index. Declaring no such BelongsTo is a compile-time error.

When OtherRecord holds more than one foreign key into this record's table - say a meeting that references the same person table both as its organizer and as whoever writes the minutes - the inverse is ambiguous. Name the foreign key column through TheInverseSelector to single one out:

struct Meeting;
struct Human
{
    Field<int, PrimaryKey::AutoAssign> id;
    HasMany<Meeting, SqlRealName { "organizer_id" }> organizedMeetings;
    HasMany<Meeting, SqlRealName { "minute_taker_id" }> minutedMeetings;
};
struct Meeting
{
    Field<int, PrimaryKey::AutoAssign> id;
    BelongsTo<&Human::id, SqlRealName { "organizer_id" }> organizer;
    BelongsTo<&Human::id, SqlRealName { "minute_taker_id" }, SqlNullable::Null> minuteTaker;
};

A meeting with many attendees is a many-to-many instead - see HasManyThrough. The worked example in docs/sql-to-lightweight.md combines both shapes.

Template Parameters

OtherRecord	The record type on the "many" side of the relationship.
TheInverseSelector	Singles out one of several foreign keys, see the RelationSelector concept.

See also: InverseBelongsToIndexOf, RelationSelector; DataMapper, Field, HasManyThrough

Definition at line 64 of file HasMany.hpp.

Member Typedef Documentation

◆ ReferencedRecord

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

using Lightweight::HasMany< OtherRecord, TheInverseSelector >::ReferencedRecord = OtherRecord

The record type of the "many" side of the relationship.

Definition at line 72 of file HasMany.hpp.

◆ ReferencedRecordList

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

using Lightweight::HasMany< OtherRecord, TheInverseSelector >::ReferencedRecordList = std::vector<std::shared_ptr<OtherRecord> >

The list of records on the "many" side of the relationship.

Definition at line 78 of file HasMany.hpp.

◆ value_type

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

using Lightweight::HasMany< OtherRecord, TheInverseSelector >::value_type = OtherRecord

Record type of the "many" side of the relationship.

Definition at line 81 of file HasMany.hpp.

◆ iterator

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

using Lightweight::HasMany< OtherRecord, TheInverseSelector >::iterator = ReferencedRecordList::iterator

Iterator type for the list of records.

Definition at line 84 of file HasMany.hpp.

◆ const_iterator

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

using Lightweight::HasMany< OtherRecord, TheInverseSelector >::const_iterator = ReferencedRecordList::const_iterator

Const iterator type for the list of records.

Definition at line 87 of file HasMany.hpp.

Member Function Documentation

◆ All() [1/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::ReferencedRecordList const & Lightweight::HasMany< OtherRecord, InverseSelector >::All ( ) const

inline

Retrieves the list of loaded records.

Note: This method will on-demand load the records if they are not already loaded, and therefore throws whatever the loader throws. It also throws SqlRequireLoadedError if no auto-loader was configured for this relation.

Definition at line 275 of file HasMany.hpp.

◆ All() [2/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::ReferencedRecordList & Lightweight::HasMany< OtherRecord, InverseSelector >::All ( )

inline

Retrieves the list of records as mutable reference.

Note: This method will on-demand load the records if they are not already loaded, and therefore throws whatever the loader throws. It also throws SqlRequireLoadedError if no auto-loader was configured for this relation.

Definition at line 252 of file HasMany.hpp.

◆ Each()

template<typename OtherRecord , auto InverseSelector>

template<typename Callable >

void Lightweight::HasMany< OtherRecord, InverseSelector >::Each ( Callable const & callable )

Iterates over the list of records and calls the given callable for each record.

Note: Use this method if you want to iterate over all records but do not need to store them all in memory, e.g. because the full data set wuold be too large.

Definition at line 260 of file HasMany.hpp.

◆ Emplace()

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::ReferencedRecordList & Lightweight::HasMany< OtherRecord, InverseSelector >::Emplace ( ReferencedRecordList && records )

inlinenoexcept

Emplaces the given list of records.

Definition at line 244 of file HasMany.hpp.

◆ LoadedRecords()

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

ReferencedRecordList * Lightweight::HasMany< OtherRecord, TheInverseSelector >::LoadedRecords ( )

inlinenoexcept

Returns the already-loaded records, or nullptr when the relation is not loaded.

Unlike All(), this never runs the on-demand loader: it reports what is present right now, which is what lets the batched relation loading walk one level deeper (With<A, B>()).

Returns: Pointer to the loaded list, or nullptr if the relation was never loaded.

Definition at line 119 of file HasMany.hpp.

◆ Count()

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE std::size_t Lightweight::HasMany< OtherRecord, InverseSelector >::Count ( ) const

inlinenoexcept

Retrieves the number of records in this 1-to-many relationship.

Definition at line 282 of file HasMany.hpp.

◆ IsEmpty()

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE bool Lightweight::HasMany< OtherRecord, InverseSelector >::IsEmpty ( ) const

inlinenoexcept

Checks if this 1-to-many relationship is empty.

Definition at line 294 of file HasMany.hpp.

References Count.

◆ At() [1/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE OtherRecord const & Lightweight::HasMany< OtherRecord, InverseSelector >::At ( std::size_t index ) const

inline

Retrieves the record at the given index.

Parameters

index The index of the record to retrieve.

Note: This method will on-demand load the records if they are not already loaded.; This method will throw if the index is out of bounds.

Definition at line 300 of file HasMany.hpp.

◆ At() [2/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE OtherRecord & Lightweight::HasMany< OtherRecord, InverseSelector >::At ( std::size_t index )

inline

Retrieves the record at the given index.

Parameters

index The index of the record to retrieve.

Note: This method will on-demand load the records if they are not already loaded.; This method will throw if the index is out of bounds.

Definition at line 307 of file HasMany.hpp.

◆ operator[]() [1/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE OtherRecord const & Lightweight::HasMany< OtherRecord, InverseSelector >::operator[] ( std::size_t index ) const

inline

Retrieves the record at the given index.

Parameters

index The index of the record to retrieve.

Note: This method will on-demand load the records if they are not already loaded.; This method will NOT throw if the index is out of bounds. The behaviour is undefined.

Definition at line 314 of file HasMany.hpp.

◆ operator[]() [2/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE OtherRecord & Lightweight::HasMany< OtherRecord, InverseSelector >::operator[] ( std::size_t index )

inline

Retrieves the record at the given index.

Parameters

index The index of the record to retrieve.

Note: This method will on-demand load the records if they are not already loaded.; This method will NOT throw if the index is out of bounds. The behaviour is undefined.

Definition at line 321 of file HasMany.hpp.

◆ begin() [1/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::iterator Lightweight::HasMany< OtherRecord, InverseSelector >::begin ( )

inline

Returns an iterator to the beginning of the record list.

Note: On-demand loads the records, and therefore throws what the loader throws.

Definition at line 329 of file HasMany.hpp.

Referenced by Lightweight::HasMany< OtherRecord, TheInverseSelector >::begin().

◆ end() [1/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::iterator Lightweight::HasMany< OtherRecord, InverseSelector >::end ( )

inline

Returns an iterator to the end of the record list.

Note: On-demand loads the records, and therefore throws what the loader throws.

Definition at line 336 of file HasMany.hpp.

Referenced by Lightweight::HasMany< OtherRecord, TheInverseSelector >::end().

◆ begin() [2/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::const_iterator Lightweight::HasMany< OtherRecord, InverseSelector >::begin ( ) const

inline

Returns a const iterator to the beginning of the record list.

Note: On-demand loads the records, and therefore throws what the loader throws.

Definition at line 344 of file HasMany.hpp.

References Lightweight::HasMany< OtherRecord, TheInverseSelector >::begin().

◆ end() [2/2]

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE HasMany< OtherRecord, InverseSelector >::const_iterator Lightweight::HasMany< OtherRecord, InverseSelector >::end ( ) const

inline

Returns a const iterator to the end of the record list.

Note: On-demand loads the records, and therefore throws what the loader throws.

Definition at line 352 of file HasMany.hpp.

References Lightweight::HasMany< OtherRecord, TheInverseSelector >::end().

◆ SetAutoLoader()

template<typename OtherRecord , auto InverseSelector>

LIGHTWEIGHT_FORCE_INLINE void Lightweight::HasMany< OtherRecord, InverseSelector >::SetAutoLoader ( Loader loader )

inlinenoexcept

Used internally to configure on-demand loading of the records.

Definition at line 219 of file HasMany.hpp.

Referenced by Lightweight::DataMapper::ConfigureRelationAutoLoading().

Member Data Documentation

◆ InverseSelector

template<typename OtherRecord , auto TheInverseSelector = AutoDetectRelation>

constexpr auto Lightweight::HasMany< OtherRecord, TheInverseSelector >::InverseSelector = TheInverseSelector

staticconstexpr

Singles out the foreign key of OtherRecord that backs this relationship.

Definition at line 75 of file HasMany.hpp.

The documentation for this class was generated from the following file:

Lightweight/DataMapper/HasMany.hpp

Public Types

Public Member Functions

Static Public Attributes

Detailed Description

Member Typedef Documentation

◆ ReferencedRecord

◆ ReferencedRecordList

◆ value_type

◆ iterator

◆ const_iterator

Member Function Documentation

◆ All() [1/2]

◆ All() [2/2]

◆ Each()

◆ Emplace()

◆ LoadedRecords()

◆ Count()

◆ IsEmpty()

◆ At() [1/2]

◆ At() [2/2]

◆ operator[]() [1/2]

◆ operator[]() [2/2]

◆ begin() [1/2]

◆ end() [1/2]

◆ begin() [2/2]

◆ end() [2/2]

◆ SetAutoLoader()

Member Data Documentation

◆ InverseSelector