Data Mapper

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

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

Typedefs
template<auto Field>
using	Lightweight::ReferencedFieldTypeOf = typename 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.

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

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<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 quoted fully qualified field name (including table name) of the given field.
template<auto... ReferencedFields>
constexpr auto	Lightweight::FullyQualifiedNamesOf
	Holds the quoted fully qualified field names of the given fields.

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 typename 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 358 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.

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.

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

Variable Documentation

RecordStorageFieldCount

template<typename Record >

constexpr size_t Lightweight::RecordStorageFieldCount

constexpr

Initial value:

=
    Reflection::FoldMembers<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.

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 170 of file Utils.hpp.

Referenced by Lightweight::SqlCoreDataMapperQueryBuilder< Record, Derived >::Range().

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 176 of file Utils.hpp.

FullyQualifiedNameOf

template<auto ReferencedField>

constexpr auto Lightweight::FullyQualifiedNameOf

inlineconstexpr

Initial value:

= SqlRawColumnNameView {
    .value = detail::FullyQualifiedNameOfImpl<ReferencedField>::value,
}

Holds the quoted fully qualified field name (including table name) of the given field.

Template Parameters

ReferencedField

auto const quotedFieldName = FullyQualifiedNameOf<&Person::id>;
static_assert(quotedFieldName.value == R"sql("Person"."id")sql");

Definition at line 311 of file Utils.hpp.

FullyQualifiedNamesOf

template<auto... ReferencedFields>

constexpr auto Lightweight::FullyQualifiedNamesOf

inlineconstexpr

Initial value:

= SqlRawColumnNameView {
    .value = detail::FullyQualifiedNamesOfImpl<ReferencedFields...>::value,
}

Holds the quoted fully qualified field names of the given fields.

auto const quotedFieldNames = FullyQualifiedNamesOf<&Person::id, &Person::name, &Person::age>;
static_assert(quotedFieldNames.value == R"sql("Person"."id", "Person"."name", "Person"."age")sql");

Definition at line 356 of file Utils.hpp.