QSqlField#
The QSqlField
class manipulates the fields in SQL database tables and views. More…
Synopsis#
Functions#
def
clear
()def
defaultValue
()def
isAutoValue
()def
isGenerated
()def
isNull
()def
isReadOnly
()def
isValid
()def
length
()def
metaType
()def
name
()def
__ne__
(other)def
__eq__
(other)def
precision
()def
requiredStatus
()def
setAutoValue
(autoVal)def
setDefaultValue
(value)def
setGenerated
(gen)def
setLength
(fieldLength)def
setMetaType
(type)def
setName
(name)def
setPrecision
(precision)def
setReadOnly
(readOnly)def
setRequired
(required)def
setRequiredStatus
(status)def
setSqlType
(type)def
setTableName
(tableName)def
setValue
(value)def
tableName
()def
typeID
()def
value
()
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description#
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
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:
field = QSqlField("age", QMetaType.fromType()) field.setValue(QPixmap()) # WRONG
However, the field will attempt to cast certain data types to the field data type where possible:
field = QSqlField("age", QMetaType.fromType()) field.setValue(QString("123")) # casts QString to int
QSqlField
objects are rarely created explicitly in application code. They are usually accessed indirectly through QSqlRecord
s that already contain a list of fields. For example:
query = QSqlQuery() ... record = query.record() field = record.field("country")
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()
.
See also
- class PySide6.QtSql.QSqlField(other)#
PySide6.QtSql.QSqlField([fieldName=””[, type=QMetaType()[, tableName=””]]])
- Parameters:
other –
PySide6.QtSql.QSqlField
type –
PySide6.QtCore.QMetaType
fieldName – str
tableName – str
Constructs a copy of other
.
This is an overloaded function.
Constructs an empty field called fieldName
of type type
in table
.
- PySide6.QtSql.QSqlField.RequiredStatus#
Specifies whether the field is required or optional.
Constant
Description
QSqlField.Required
The field must be specified when inserting records.
QSqlField.Optional
The fields doesn’t have to be specified when inserting records.
QSqlField.Unknown
The database driver couldn’t determine whether the field is required or optional.
See also
- PySide6.QtSql.QSqlField.clear()#
Clears the value of the field and sets it to NULL. If the field is read-only, nothing happens.
See also
- PySide6.QtSql.QSqlField.defaultValue()#
- Return type:
object
Returns the field’s default value (which may be NULL).
- PySide6.QtSql.QSqlField.isAutoValue()#
- Return type:
bool
Returns true
if the value is auto-generated by the database, for example auto-increment primary key values.
Note
When using the ODBC driver, due to limitations in the ODBC API, the 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 record()
or primaryIndex()
.
See also
- PySide6.QtSql.QSqlField.isGenerated()#
- Return type:
bool
Returns true
if the field is generated; otherwise returns false.
- PySide6.QtSql.QSqlField.isNull()#
- Return type:
bool
Returns true
if the field’s value is NULL; otherwise returns false.
See also
- PySide6.QtSql.QSqlField.isReadOnly()#
- Return type:
bool
Returns true
if the field’s value is read-only; otherwise returns false.
- PySide6.QtSql.QSqlField.isValid()#
- Return type:
bool
Returns true
if the field’s variant type is valid; otherwise returns false
.
- PySide6.QtSql.QSqlField.length()#
- Return type:
int
Returns the field’s length.
If the returned value is negative, it means that the information is not available from the database.
- PySide6.QtSql.QSqlField.metaType()#
- Return type:
Returns 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.
See also
- PySide6.QtSql.QSqlField.name()#
- Return type:
str
Returns the name of the field.
See also
- PySide6.QtSql.QSqlField.__ne__(other)#
- Parameters:
other –
PySide6.QtSql.QSqlField
- Return type:
bool
Returns true
if the field is unequal to other
; otherwise returns false.
- PySide6.QtSql.QSqlField.__eq__(other)#
- Parameters:
other –
PySide6.QtSql.QSqlField
- Return type:
bool
Returns true
if the field is equal to other
; otherwise returns false.
- PySide6.QtSql.QSqlField.precision()#
- Return type:
int
Returns 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.
- PySide6.QtSql.QSqlField.requiredStatus()#
- Return type:
Returns true
if this is a required field; otherwise returns false
. An INSERT
will fail if a required field does not have a value.
- PySide6.QtSql.QSqlField.setAutoValue(autoVal)#
- Parameters:
autoVal – bool
Marks the field as an auto-generated value if autoVal
is true.
See also
- PySide6.QtSql.QSqlField.setDefaultValue(value)#
- Parameters:
value – object
Sets the default value used for this field to value
.
- PySide6.QtSql.QSqlField.setGenerated(gen)#
- Parameters:
gen – bool
Sets the generated state. If gen
is false, no SQL will be generated for this field; otherwise, Qt classes such as QSqlQueryModel
and QSqlTableModel
will generate SQL for this field.
- PySide6.QtSql.QSqlField.setLength(fieldLength)#
- Parameters:
fieldLength – int
Sets the field’s length to fieldLength
. For strings this is the maximum number of characters the string can hold; the meaning varies for other types.
- PySide6.QtSql.QSqlField.setMetaType(type)#
- Parameters:
type –
PySide6.QtCore.QMetaType
Set’s the field’s variant type to type
.
- PySide6.QtSql.QSqlField.setName(name)#
- Parameters:
name – str
Sets the name of the field to name
.
See also
- PySide6.QtSql.QSqlField.setPrecision(precision)#
- Parameters:
precision – int
Sets the field’s precision
. This only affects numeric fields.
- PySide6.QtSql.QSqlField.setReadOnly(readOnly)#
- Parameters:
readOnly – bool
Sets the read only flag of the field’s value to readOnly
. A read-only field cannot have its value set with setValue()
and cannot be cleared to NULL with clear()
.
See also
- PySide6.QtSql.QSqlField.setRequired(required)#
- Parameters:
required – bool
Sets the required status of this field to Required
if required
is true; otherwise sets it to Optional
.
See also
- PySide6.QtSql.QSqlField.setRequiredStatus(status)#
- Parameters:
status –
RequiredStatus
Sets the required status of this field to required
.
- PySide6.QtSql.QSqlField.setSqlType(type)#
- Parameters:
type – int
- PySide6.QtSql.QSqlField.setTableName(tableName)#
- Parameters:
tableName – str
Sets the tableName
of the field to table
.
See also
- PySide6.QtSql.QSqlField.setValue(value)#
- Parameters:
value – object
Sets the value of the field to value
. If the field is read-only ( isReadOnly()
returns true
), nothing happens.
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()
.
See also
- PySide6.QtSql.QSqlField.tableName()#
- Return type:
str
Returns the tableName of the field.
Note
When using the QPSQL driver, due to limitations in the libpq library, the tableName()
field is not populated in a QSqlField
resulting from a QSqlRecord
obtained by record()
of a forward-only query.
See also
- PySide6.QtSql.QSqlField.typeID()#
- Return type:
int
- PySide6.QtSql.QSqlField.value()#
- Return type:
object
Returns the value of the field as a QVariant
.
Use isNull()
to check if the field’s value is NULL.
See also