Qt
Internal/Contributor docs for the Qt SDK. <b>Note:</b> These are NOT official API docs; those are found <a href='https://doc.qt.io/'>here</a>.
|
The QSqlField class manipulates the fields in SQL database tables and views. More...
#include <qsqlfield.h>
Public Types | |
enum | RequiredStatus { Unknown = -1 , Optional = 0 , Required = 1 } |
Specifies whether the field is required or optional. More... | |
Public Member Functions | |
QSqlField (const QString &fieldName=QString(), QMetaType type=QMetaType(), const QString &tableName=QString()) | |
QSqlField (const QSqlField &other) | |
Constructs a copy of other. | |
QSqlField & | operator= (const QSqlField &other) |
Sets the field equal to other. | |
QSqlField (QSqlField &&other) noexcept=default | |
~QSqlField () | |
Destroys the object and frees any allocated resources. | |
void | swap (QSqlField &other) noexcept |
bool | operator== (const QSqlField &other) const |
Returns true if the field is equal to other; otherwise returns false. | |
bool | operator!= (const QSqlField &other) const |
Returns true if the field is unequal to other; otherwise returns false. | |
void | setValue (const QVariant &value) |
Sets \l value to value. | |
QVariant | value () const |
Returns the value of \l value. | |
void | setName (const QString &name) |
Sets \l name to name. | |
QString | name () const |
Returns the value of \l name. | |
void | setTableName (const QString &tableName) |
Sets \l tableName to tableName. | |
QString | tableName () const |
Returns the \l tableName. | |
bool | isNull () const |
Returns true if the field's value is NULL; otherwise returns false. | |
void | setReadOnly (bool readOnly) |
Sets \l readOnly to readOnly. | |
bool | isReadOnly () const |
Returns the value of \l readOnly. | |
void | clear () |
Clears the value of the field and sets it to NULL. | |
bool | isAutoValue () const |
Returns the value of \l autoValue. | |
QMetaType | metaType () const |
Returns the value of \l metaType. | |
void | setMetaType (QMetaType type) |
Sets \l metaType to type. | |
void | setRequiredStatus (RequiredStatus status) |
Sets \l requiredStatus to required. | |
void | setRequired (bool required) |
Sets the required status of this field to \l Required if required is true; otherwise sets it to \l Optional. | |
void | setLength (int fieldLength) |
Sets \l length to fieldLength. | |
void | setPrecision (int precision) |
Sets \l precision to precision. | |
void | setDefaultValue (const QVariant &value) |
Sets \l defaultValue to value. | |
void | setGenerated (bool gen) |
Sets \l generated to gen. | |
void | setAutoValue (bool autoVal) |
Sets \l autoValue to autoVal. | |
RequiredStatus | requiredStatus () const |
Returns the value of \l requiredStatus. | |
int | length () const |
Returns the value of \l length. | |
int | precision () const |
Returns the value of \l precision. | |
QVariant | defaultValue () const |
Sets the value of \l defaultValue. | |
bool | isGenerated () const |
Returns the value of \l generated. | |
bool | isValid () const |
Returns true if the field's variant type is valid; otherwise returns false . | |
Properties | |
QVariant | value |
QVariant | defaultValue |
QString | name |
This property holds the name of the field. | |
QString | tableName |
QMetaType | metaType |
RequiredStatus | requiredStatus |
bool | readOnly |
bool | generated |
bool | autoValue |
int | length |
int | precision |
The QSqlField class manipulates the fields in SQL database tables and views.
\inmodule QtSql
QSqlField represents the characteristics of a single column in a database table or view, such as the data type and column name. A field also contains the value of the database column, which can be viewed or changed.
Field data values are stored as QVariants. Using an incompatible type is not permitted. For example:
However, the field will attempt to cast certain data types to the field data type where possible:
QSqlField objects are rarely created explicitly in application code. They are usually accessed indirectly through \l{QSqlRecord}s that already contain a list of fields. For example:
\dots
A QSqlField object can provide some meta-data about the field, for example, its name(), variant type(), length(), precision(), defaultValue(), typeID(), and its requiredStatus(), isGenerated() and isReadOnly(). The field's data can be checked to see if it isNull(), and its value() retrieved. When editing the data can be set with setValue() or set to NULL with clear().
Definition at line 18 of file qsqlfield.h.
Specifies whether the field is required or optional.
\value Required The field must be specified when inserting records. \value Optional The fields doesn't have to be specified when inserting records. \value Unknown The database driver couldn't determine whether the field is required or optional.
Enumerator | |
---|---|
Unknown | |
Optional | |
Required |
Definition at line 22 of file qsqlfield.h.
|
explicit |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Constructs an empty field called fieldName of type type in table.
Definition at line 129 of file qsqlfield.cpp.
|
default |
Constructs a copy of other.
|
defaultnoexcept |
|
default |
Destroys the object and frees any allocated resources.
void QSqlField::clear | ( | ) |
Clears the value of the field and sets it to NULL.
If the field is read-only, nothing happens.
Definition at line 281 of file qsqlfield.cpp.
References isReadOnly(), and QSqlFieldPrivate::type.
QVariant QSqlField::defaultValue | ( | ) | const |
Sets the value of \l defaultValue.
Definition at line 470 of file qsqlfield.cpp.
References QSqlFieldPrivate::def.
bool QSqlField::isAutoValue | ( | ) | const |
Returns the value of \l autoValue.
Definition at line 557 of file qsqlfield.cpp.
References QSqlFieldPrivate::autoval.
bool QSqlField::isGenerated | ( | ) | const |
Returns the value of \l generated.
Definition at line 503 of file qsqlfield.cpp.
References QSqlFieldPrivate::gen.
Referenced by QSqlRecord::isGenerated().
bool QSqlField::isNull | ( | ) | const |
Returns true
if the field's value is NULL; otherwise returns false.
Definition at line 399 of file qsqlfield.cpp.
Referenced by QDB2Driver::formatValue(), QMYSQLDriver::formatValue(), QODBCDriver::formatValue(), QPSQLDriver::formatValue(), QSqlDriver::formatValue(), and QSqlRecord::isNull().
bool QSqlField::isReadOnly | ( | ) | const |
Returns the value of \l readOnly.
Definition at line 388 of file qsqlfield.cpp.
References QSqlFieldPrivate::ro.
Referenced by clear(), and setValue().
bool QSqlField::isValid | ( | ) | const |
Returns true
if the field's variant type is valid; otherwise returns false
.
Definition at line 512 of file qsqlfield.cpp.
References QMetaType::isValid(), and QSqlFieldPrivate::type.
int QSqlField::length | ( | ) | const |
Returns the value of \l length.
Definition at line 444 of file qsqlfield.cpp.
References QSqlFieldPrivate::len.
QMetaType QSqlField::metaType | ( | ) | const |
Returns the value of \l metaType.
Definition at line 338 of file qsqlfield.cpp.
References QSqlFieldPrivate::type.
QString QSqlField::name | ( | ) | const |
Returns the value of \l name.
Definition at line 317 of file qsqlfield.cpp.
References QSqlFieldPrivate::nm.
|
inline |
Returns true
if the field is unequal to other; otherwise returns false.
Definition at line 47 of file qsqlfield.h.
References operator==(), and other().
bool QSqlField::operator== | ( | const QSqlField & | other | ) | const |
Returns true
if the field is equal to other; otherwise returns false.
Definition at line 158 of file qsqlfield.cpp.
References other().
int QSqlField::precision | ( | ) | const |
Returns the value of \l precision.
Definition at line 462 of file qsqlfield.cpp.
References QSqlFieldPrivate::prec.
QSqlField::RequiredStatus QSqlField::requiredStatus | ( | ) | const |
Returns the value of \l requiredStatus.
Definition at line 424 of file qsqlfield.cpp.
References QSqlFieldPrivate::req.
void QSqlField::setAutoValue | ( | bool | autoVal | ) |
Sets \l autoValue to autoVal.
Definition at line 565 of file qsqlfield.cpp.
References QSqlFieldPrivate::autoval.
Sets \l defaultValue to value.
Definition at line 218 of file qsqlfield.cpp.
References QSqlFieldPrivate::def, and value.
void QSqlField::setGenerated | ( | bool | gen | ) |
Sets \l generated to gen.
Definition at line 239 of file qsqlfield.cpp.
References QSqlFieldPrivate::gen.
Referenced by QSqlQueryModel::insertColumns().
void QSqlField::setLength | ( | int | fieldLength | ) |
Sets \l length to fieldLength.
Definition at line 191 of file qsqlfield.cpp.
References QSqlFieldPrivate::len.
Sets \l metaType to type.
Definition at line 346 of file qsqlfield.cpp.
References QSqlFieldPrivate::type.
Referenced by qCreateParamString(), and QMimerSQLResult::record().
Sets \l name to name.
Definition at line 292 of file qsqlfield.cpp.
References name, and QSqlFieldPrivate::nm.
Referenced by QMimerSQLResult::record(), and QPSQLResult::record().
void QSqlField::setPrecision | ( | int | precision | ) |
Sets \l precision to precision.
Definition at line 200 of file qsqlfield.cpp.
References QSqlFieldPrivate::prec, and precision.
Referenced by QMimerSQLDriver::record().
void QSqlField::setReadOnly | ( | bool | readOnly | ) |
Sets \l readOnly to readOnly.
Definition at line 301 of file qsqlfield.cpp.
References readOnly, and QSqlFieldPrivate::ro.
Referenced by QSqlQueryModel::insertColumns().
|
inline |
Sets the required status of this field to \l Required if required is true; otherwise sets it to \l Optional.
Definition at line 80 of file qsqlfield.h.
References Required.
Referenced by QMimerSQLDriver::record().
void QSqlField::setRequiredStatus | ( | RequiredStatus | status | ) |
Sets \l requiredStatus to required.
Definition at line 174 of file qsqlfield.cpp.
References QSqlFieldPrivate::req.
Sets \l tableName to tableName.
Definition at line 574 of file qsqlfield.cpp.
References QSqlFieldPrivate::table, and tableName.
Sets \l value to value.
Definition at line 269 of file qsqlfield.cpp.
References isReadOnly(), and value.
Referenced by QSqlField_snippets(), and QMimerSQLResult::record().
QString QSqlField::tableName | ( | ) | const |
Returns the \l tableName.
Definition at line 593 of file qsqlfield.cpp.
References QSqlFieldPrivate::table.
|
inline |
Returns the value of \l value.
Definition at line 50 of file qsqlfield.h.
|
readwrite |
If the value is auto-generated by the database, for example auto-increment primary key values, this value is true
.
isAutoValue()
field is only populated in a QSqlField resulting from a QSqlRecord obtained by executing a SELECT
query. It is false
in a QSqlField resulting from a QSqlRecord returned from QSqlDatabase::record() or QSqlDatabase::primaryIndex(). Definition at line 32 of file qsqlfield.h.
|
readwrite |
This property holds the default value for this field. Only some database drivers supports this property. Currently those are SQLite, PostgreSQL, Oracle and MySQL/MariaDB.
Definition at line 25 of file qsqlfield.h.
|
readwrite |
This property holds the generated state. If generated is false
, no SQL will be generated for this field; otherwise, Qt classes such as QSqlQueryModel and QSqlTableModel will generate SQL for this field.
Definition at line 31 of file qsqlfield.h.
|
readwrite |
This property holds the field's length.
If the value is negative, it means that the information is not available from the database. For strings this is the maximum number of characters the string can hold; the meaning varies for other types.
Definition at line 33 of file qsqlfield.h.
|
readwrite |
This property holds the field's type as stored in the database. Note that the actual value might have a different type, Numerical values that are too large to store in a long int or double are usually stored as strings to prevent precision loss.
Definition at line 28 of file qsqlfield.h.
Referenced by QDB2Driver::formatValue(), QIBaseDriver::formatValue(), QMYSQLDriver::formatValue(), QOCIDriver::formatValue(), QODBCDriver::formatValue(), QPSQLDriver::formatValue(), QSqlDriver::formatValue(), and QMimerSQLResult::record().
|
readwrite |
This property holds the name of the field.
This can be the column name or a user given alias.
Definition at line 26 of file qsqlfield.h.
Referenced by QSqlRecord::fieldName(), QSqlRecord::indexOf(), and setName().
|
readwrite |
This property holds the field's precision; this is only meaningful for numeric types.
If the returned value is negative, it means that the information is not available from the database.
Definition at line 34 of file qsqlfield.h.
Referenced by QMYSQLDriver::formatValue(), and setPrecision().
|
readwrite |
When this property is true
then this QSqlField cannot be modified. A read-only field cannot have its value set with setValue() and cannot be cleared to NULL with clear().
Definition at line 30 of file qsqlfield.h.
Referenced by setReadOnly().
|
readwrite |
This property holds the RequiredStatus of the field. An INSERT
will fail if a required field does not have a value.
Definition at line 29 of file qsqlfield.h.
|
readwrite |
This property holds the tableName of the field.
tableName()
field is not populated in a QSqlField resulting from a QSqlRecord obtained by QSqlQuery::record() of a forward-only query. Definition at line 27 of file qsqlfield.h.
Referenced by setTableName().
|
readwrite |
This property holds the value as a QVariant
Setting a value to a read-only QSqlField is a no-op. If the data type of value differs from the field's current data type, an attempt is made to cast it to the proper type. This preserves the data type of the field in the case of assignment, e.g. a QString to an integer data type.
To set the value to NULL, use clear().
Definition at line 24 of file qsqlfield.h.
Referenced by QDB2Driver::formatValue(), QIBaseDriver::formatValue(), QMYSQLDriver::formatValue(), QOCIDriver::formatValue(), QODBCDriver::formatValue(), QPSQLDriver::formatValue(), QSqlDriver::formatValue(), setDefaultValue(), setValue(), and QSqlRecord::value().