The data mapper is a high level API for mapping records to and from the database using high level C++ syntax. More...

Concepts
concept	Lightweight::DataMapperRecord
	Represents a record type that can be used with the DataMapper.

concept	Lightweight::FieldWithStorage

concept	Lightweight::HasDescription
	Satisfied when a Description specialization exists for the given record type.

Classes
class	Lightweight::BelongsTo< TheReferencedField, ColumnNameOverrideString, Nullable >
	Represents a one-to-one relationship. More...

class	Lightweight::DataMapper
	Main API for mapping records to and from the database using high level C++ syntax. More...

class	Lightweight::SqlRequireLoadedError
	Represents an error when a record is required to be loaded but is not. More...

struct	Lightweight::Field< T, P1, P2 >
	Represents a single column in a table. More...

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

class	Lightweight::HasManyThrough< ReferencedRecordT, ThroughRecordT >
	This API represents a many-to-many relationship between two records through a third record. More...

class	Lightweight::HasOneThrough< OtherTable, ThroughTable >
	Represents a one-to-one relationship through a join table. More...

class	Lightweight::SqlCoreDataMapperQueryBuilder< Record, Derived, QueryOptions >

class	Lightweight::SqlAllFieldsQueryBuilder< Record, QueryOptions, Execution >
	Represents a query builder that retrieves all fields of a record. More...

struct	Lightweight::RecordMemberList< MemberPointers >
	Compile-time list of a record's members, stored as pointers-to-member. More...

struct	Lightweight::Description< Record >
	Customization point providing pre-computed reflection metadata for a record type. More...

Typedefs
template<auto Field>
using	Lightweight::ReferencedFieldTypeOf = std::remove_cvref_t< decltype(std::declval< MemberClassType< decltype(Field)> >().*Field)>::ValueType
	Retrieves the type of a member field in a record.

template<size_t... Ints>
using	Lightweight::SqlElements = std::integer_sequence< size_t, Ints... >
	Represents a sequence of indexes that can be used alongside Query() to retrieve only part of the record.

template<std::size_t I, typename Record >
using	Lightweight::RecordMemberTypeOf = detail::RecordMemberTypeOfDispatch< I, std::remove_cvref_t< Record >, HasDescription< Record > >::type
	Type of the member at index `I` — from the descriptor if present, else via reflection.

Functions
template<typename Record >
LIGHTWEIGHT_FORCE_INLINE RecordPrimaryKeyType< Record >	Lightweight::GetPrimaryKeyField (Record const &record) noexcept

template<std::size_t I, typename Record >
constexpr decltype(auto)	Lightweight::GetRecordMemberAt (Record &&record)
	Returns a reference to the member at index `I` — from the descriptor if present, else via reflection.

template<typename Record , typename Callable >
constexpr void	Lightweight::EnumerateRecordMembers (Record &record, Callable &&callable)
	Invokes `callable` as `callable<I>(member)` for each member of `record`.

template<typename ElementMask , typename Record , typename Callable >
constexpr void	Lightweight::EnumerateRecordMembers (Record &record, Callable &&callable)
	Invokes `callable` as `callable<I>(member)` for each member selected by `ElementMask`.

template<typename Record , typename Callable >
constexpr void	Lightweight::EnumerateRecordMembers (Callable &&callable)
	Invokes `callable` as `callable<I, MemberType>()` for each member of `Record`.

template<typename Record , typename Callable , typename ResultType >
constexpr ResultType	Lightweight::FoldRecordMembers (ResultType initialValue, Callable const &callable)
	Folds over a record's members as `result = callable<I, MemberType>(result)`.

Variables
template<typename Record >
constexpr size_t	Lightweight::RecordStorageFieldCount

template<typename T >
constexpr bool	Lightweight::HasPrimaryKey = detail::CheckFieldProperty<[]<typename Field>() { return IsPrimaryKey<Field>; }, T>
	Tests if the given record type does contain a primary key.

template<typename T >
constexpr bool	Lightweight::HasAutoIncrementPrimaryKey
	Tests if the given record type does contain an auto increment primary key.

template<typename Record >
constexpr std::size_t	Lightweight::RecordMemberCount
	Number of members in a record — from the descriptor if present, else via reflection.

template<std::size_t I, typename Record >
constexpr std::string_view	Lightweight::FieldNameAt = detail::FieldNameAt<I, Record>()
	Returns the SQL field name of the given field index in the record.

template<typename Record >
constexpr std::string_view	Lightweight::RecordTableName = detail::RecordTableNameImpl<Record>::Value
	Holds the SQL tabl ename for the given record type.

template<auto ReferencedField>
constexpr auto	Lightweight::FullyQualifiedNameOf
	Holds the fully qualified column reference (table + column) for the given field.

Detailed Description

The data mapper is a high level API for mapping records to and from the database using high level C++ syntax.

Typedef Documentation

◆ ReferencedFieldTypeOf

template<auto Field>

using Lightweight::ReferencedFieldTypeOf = typedef std::remove_cvref_t<decltype(std::declval<MemberClassType<decltype(Field)> >().*Field)>::ValueType

Retrieves the type of a member field in a record.

Field must be a member of the record type, and it must be a field type, e.g. Field<int> or BelongsTo<OtherRecord>.

using MyRecord = Record {
   Field<int> value;
   Field<std::optional<char>> optionalValue;
};
 
using MyFieldType = ReferencedFieldTypeOf<&MyRecord::value>; // Retrieves `int`
using MyOptionalFieldType = ReferencedFieldTypeOf<&MyRecord::optionalValue>; // Retrieves `std::optional<char>`

Definition at line 390 of file Field.hpp.

◆ SqlElements

template<size_t... Ints>

using Lightweight::SqlElements = typedef std::integer_sequence<size_t, Ints...>

Represents a sequence of indexes that can be used alongside Query() to retrieve only part of the record.

Definition at line 20 of file Record.hpp.

◆ RecordMemberTypeOf

template<std::size_t I, typename Record >

using Lightweight::RecordMemberTypeOf = typedef detail::RecordMemberTypeOfDispatch<I, std::remove_cvref_t<Record>, HasDescription<Record> >::type

Type of the member at index I — from the descriptor if present, else via reflection.

Definition at line 162 of file Description.hpp.

Function Documentation

◆ GetPrimaryKeyField()

template<typename Record >

LIGHTWEIGHT_FORCE_INLINE RecordPrimaryKeyType< Record > Lightweight::GetPrimaryKeyField ( Record const & record )

inlinenoexcept

Returns the first primary key field of the record.

Definition at line 178 of file Record.hpp.

References Lightweight::EnumerateRecordMembers().

Referenced by Lightweight::DataMapper::ConfigureRelationAutoLoading(), and Lightweight::DataMapper::Create().

◆ GetRecordMemberAt()

template<std::size_t I, typename Record >

constexpr decltype(auto) Lightweight::GetRecordMemberAt ( Record && record )

constexpr

Returns a reference to the member at index I — from the descriptor if present, else via reflection.

Definition at line 167 of file Description.hpp.

◆ EnumerateRecordMembers() [1/3]

template<typename Record , typename Callable >

constexpr void Lightweight::EnumerateRecordMembers	(	Record &	record,
		Callable &&	callable
	)

constexpr

Invokes callable as callable<I>(member) for each member of record.

Mirrors Reflection::EnumerateMembers(object, callable) but reads the descriptor when present, avoiding the aggregate-decomposition (ToTuple) instantiation.

Definition at line 181 of file Description.hpp.

Referenced by Lightweight::DataMapper::ConfigureRelationAutoLoading(), Lightweight::DataMapper::Delete(), Lightweight::GetPrimaryKeyField(), Lightweight::DataMapper::LoadRelations(), Lightweight::DataMapper::SetId(), Lightweight::DataMapper::SetModifiedState(), and Lightweight::DataMapper::Update().

◆ EnumerateRecordMembers() [2/3]

template<typename ElementMask , typename Record , typename Callable >

constexpr void Lightweight::EnumerateRecordMembers	(	Record &	record,
		Callable &&	callable
	)

constexpr

Invokes callable as callable<I>(member) for each member selected by ElementMask.

Mirrors Reflection::EnumerateMembers<ElementMask>(object, callable) (partial-column queries) but reads the descriptor when present. ElementMask is a std::integer_sequence<std::size_t, ...>.

Definition at line 195 of file Description.hpp.

◆ EnumerateRecordMembers() [3/3]

template<typename Record , typename Callable >

constexpr void Lightweight::EnumerateRecordMembers ( Callable && callable )

constexpr

Invokes callable as callable<I, MemberType>() for each member of Record.

Mirrors Reflection::EnumerateMembers<Object>(callable) but reads the descriptor when present.

Definition at line 209 of file Description.hpp.

◆ FoldRecordMembers()

template<typename Record , typename Callable , typename ResultType >

constexpr ResultType Lightweight::FoldRecordMembers	(	ResultType	initialValue,
		Callable const &	callable
	)

constexpr

Folds over a record's members as result = callable<I, MemberType>(result).

Mirrors Reflection::FoldMembers<Object>(initialValue, callable) but reads the descriptor when present.

Definition at line 222 of file Description.hpp.

Variable Documentation

◆ RecordStorageFieldCount

template<typename Record >

constexpr size_t Lightweight::RecordStorageFieldCount

constexpr

Initial value:

=
    FoldRecordMembers<Record>(size_t { 0 }, []<size_t I, typename Field>(size_t const accum) constexpr {
        if constexpr (FieldWithStorage<Field>)
            return accum + 1;
        else
            return accum;
    })

Represents the number of fields with storage in a record.

Definition at line 137 of file Record.hpp.

◆ HasPrimaryKey

template<typename T >

constexpr bool Lightweight::HasPrimaryKey = detail::CheckFieldProperty<[]<typename Field>() { return IsPrimaryKey<Field>; }, T>

constexpr

Tests if the given record type does contain a primary key.

Definition at line 165 of file Record.hpp.

◆ HasAutoIncrementPrimaryKey

template<typename T >

constexpr bool Lightweight::HasAutoIncrementPrimaryKey

constexpr

Initial value:

=

detail::CheckFieldProperty<[]<typename Field>() { return IsAutoIncrementPrimaryKey<Field>; }, T>

Tests if the given record type does contain an auto increment primary key.

Definition at line 171 of file Record.hpp.

◆ RecordMemberCount

template<typename Record >

constexpr std::size_t Lightweight::RecordMemberCount

constexpr

Initial value:

= []() constexpr {
    if constexpr (HasDescription<Record>)
        return Description<std::remove_cvref_t<Record>>::FieldCount;
    else
        return Reflection::CountMembers<Record>;
}()

Number of members in a record — from the descriptor if present, else via reflection.

Definition at line 152 of file Description.hpp.

◆ FieldNameAt

template<std::size_t I, typename Record >

constexpr std::string_view Lightweight::FieldNameAt = detail::FieldNameAt<I, Record>()

inlineconstexpr

Returns the SQL field name of the given field index in the record.

Definition at line 261 of file Utils.hpp.

◆ RecordTableName

template<typename Record >

constexpr std::string_view Lightweight::RecordTableName = detail::RecordTableNameImpl<Record>::Value

constexpr

Holds the SQL tabl ename for the given record type.

Definition at line 267 of file Utils.hpp.

Referenced by Lightweight::SqlWhereClauseBuilder< Derived >::InnerJoin().

◆ FullyQualifiedNameOf

template<auto ReferencedField>

constexpr auto Lightweight::FullyQualifiedNameOf

inlineconstexpr

Initial value:

= SqlQualifiedTableColumnName {
 
    .tableName = RecordTableName<MemberClassType<decltype(ReferencedField)>>,
 
    .columnName = FieldNameOf<ReferencedField>,
}

Holds the fully qualified column reference (table + column) for the given field.

Template Parameters

ReferencedField A pointer-to-member identifying the field.

constexpr auto ref = FullyQualifiedNameOf<&Person::id>;
static_assert(ref.tableName == "Person");
static_assert(ref.columnName == "id");

The result is an SqlQualifiedTableColumnName accepted by every column-name entry point in the builder (Field, Fields, Where, OrderBy, GroupBy, Aggregate::*, joins). The builder applies the quoting.

Definition at line 343 of file Utils.hpp.

Concepts

Classes

Typedefs

Functions

Variables

Detailed Description

Typedef Documentation

◆ ReferencedFieldTypeOf

◆ SqlElements

◆ RecordMemberTypeOf

Function Documentation

◆ GetPrimaryKeyField()

◆ GetRecordMemberAt()

◆ EnumerateRecordMembers() [1/3]

◆ EnumerateRecordMembers() [2/3]

◆ EnumerateRecordMembers() [3/3]

◆ FoldRecordMembers()

Variable Documentation

◆ RecordStorageFieldCount

◆ HasPrimaryKey

◆ HasAutoIncrementPrimaryKey

◆ RecordMemberCount

◆ FieldNameAt

◆ RecordTableName

◆ FullyQualifiedNameOf