Class: QgsField¶
- class qgis.core.QgsField¶
Bases:
sip.wrapper
Encapsulate a field in an attribute table or data source.
QgsField
stores metadata about an attribute field, including name, type length, and if applicable, precision.Note
QgsField
objects are implicitly shared.QgsField(name: str = ‘’, type: QVariant.Type = QVariant.Invalid, typeName: str = ‘’, len: int = 0, prec: int = 0, comment: str = ‘’, subType: QVariant.Type = QVariant.Invalid) Constructor. Constructs a new
QgsField
object.- Parameters
name – Field name
type – Field variant type, currently supported: String / Int / Double
typeName – Field type (e.g., char, varchar, text, int, serial, double). Field types are usually unique to the source and are stored exactly as returned from the data store.
len – Field length
prec – Field precision. Usually decimal places but may also be used in conjunction with other fields types (e.g., variable character fields)
comment – Comment for the field
subType – If the field is a collection, its element’s type. When all the elements don’t need to have the same type, leave this to QVariant.Invalid.
QgsField(other:
QgsField
) Copy constructorMethods
Returns the alias for the field (the friendly displayed name of the field ), or an empty string if there is no alias.
Returns the field comment
Returns constraints which are present for the field.
Converts the provided variant to a compatible format
Returns the expression used when calculating the default value for the field.
Returns the name to use when displaying this field.
Returns the name to use when displaying this field and adds the alias in parenthesis if it is defined.
Formats string for display
Returns the type to use when displaying this field, including the length and precision of the datatype if applicable.
Gets the editor widget setup for the field.
Returns if this field is a date and/or time type.
Returns if this field is numeric.
Returns
True
if this field is a read-only field.Gets the length of the field.
Returns the name of the field.
Gets the precision of the field.
Sets the alias for the field (the friendly displayed name of the field ).
Set the field comment
Sets constraints which are present for the field.
Sets an expression to use when calculating the default value for the field.
Set the editor widget setup for the field.
Set the field length.
Set the field name.
Set the field precision.
Make field read-only if
readOnly
is set to true.If the field is a collection, set its element's type.
Set variant type.
Set the field type.
If the field is a collection, gets its element's type.
Gets variant type of the field as it will be retrieved from data source
Gets the field type.
Attributes
- alias(self) str ¶
Returns the alias for the field (the friendly displayed name of the field ), or an empty string if there is no alias.
See also
New in version 3.0.
- Return type
str
- comment(self) str ¶
Returns the field comment
- Return type
str
- constraints(self) QgsFieldConstraints ¶
Returns constraints which are present for the field.
See also
New in version 3.0.
- Return type
- convertCompatible(self, v: Any) bool ¶
Converts the provided variant to a compatible format
- Parameters
v (Any) – The value to convert
:raises ValueError if the value could not be converted to a compatible format
- Return type
bool
- defaultValueDefinition(self) QgsDefaultValue ¶
Returns the expression used when calculating the default value for the field.
- Return type
- Returns
expression evaluated when calculating default values for field, or an empty string if no default is set
See also
New in version 3.0.
- displayName(self) str ¶
Returns the name to use when displaying this field. This will be the field alias if set, otherwise the field name.
See also
See also
New in version 3.0.
- Return type
str
- displayNameWithAlias(self) str ¶
Returns the name to use when displaying this field and adds the alias in parenthesis if it is defined.
This will be used when working close to the data structure (i.e. building expressions and queries), when the real field name must be shown but the alias is also useful to understand what the field represents.
See also
See also
New in version 3.12.
- Return type
str
- displayString(self, v: Any) str ¶
Formats string for display
- Parameters
v (Any) –
- Return type
str
- displayType(self, showConstraints: bool = False) str ¶
Returns the type to use when displaying this field, including the length and precision of the datatype if applicable.
This will be used when the full datatype with details has to displayed to the user.
See also
New in version 3.14.
- Parameters
showConstraints (bool = False) –
- Return type
str
- editorWidgetSetup(self) QgsEditorWidgetSetup ¶
Gets the editor widget setup for the field.
Defaults may be set by the provider and can be overridden by manual field configuration.
- Return type
- Returns
the value
- isDateOrTime(self) bool ¶
Returns if this field is a date and/or time type.
New in version 3.6.
- Return type
bool
- isNumeric(self) bool ¶
Returns if this field is numeric. Any integer or floating point type will return
True
for this.New in version 2.18.
- Return type
bool
- isReadOnly(self) bool ¶
Returns
True
if this field is a read-only field. This is the case for providers which support generated fields for instance.New in version 3.18.
- Return type
bool
- length(self) int ¶
Gets the length of the field.
- Return type
int
- Returns
int containing the length of the field
- name(self) str ¶
Returns the name of the field.
See also
See also
- Return type
str
- precision(self) int ¶
Gets the precision of the field. Not all field types have a related precision.
- Return type
int
- Returns
int containing the precision or zero if not applicable to the field type.
- setAlias(self, alias: str)¶
Sets the alias for the field (the friendly displayed name of the field ).
- Parameters
alias (str) – field alias, or empty string to remove an existing alias
See also
New in version 3.0.
- setComment(self, comment: str)¶
Set the field comment
- Parameters
comment (str) –
- setConstraints(self, constraints: QgsFieldConstraints)¶
Sets constraints which are present for the field.
See also
New in version 3.0.
- Parameters
constraints (QgsFieldConstraints) –
- setDefaultValueDefinition(self, defaultValueDefinition: QgsDefaultValue)¶
Sets an expression to use when calculating the default value for the field.
- Parameters
defaultValueDefinition (QgsDefaultValue) – expression to evaluate when calculating default values for field. Pass a default constructed :py:class:`QgsDefaultValue`() to reset.
See also
New in version 3.0.
- setEditorWidgetSetup(self, v: QgsEditorWidgetSetup)¶
Set the editor widget setup for the field.
- Parameters
v (QgsEditorWidgetSetup) – The value to set
- setLength(self, len: int)¶
Set the field length.
- Parameters
len (int) – Length of the field
- setName(self, name: str)¶
Set the field name.
- Parameters
name (str) – Name of the field
- setPrecision(self, precision: int)¶
Set the field precision.
- Parameters
precision (int) – Precision of the field
- setReadOnly(self, readOnly: bool)¶
Make field read-only if
readOnly
is set to true. This is the case for providers which support generated fields for instance.New in version 3.18.
- Parameters
readOnly (bool) –
- setSubType(self, subType: QVariant.Type)¶
If the field is a collection, set its element’s type. When all the elements don’t need to have the same type, set this to QVariant.Invalid.
New in version 3.0.
- Parameters
subType (QVariant.Type) –
- setType(self, type: QVariant.Type)¶
Set variant type.
- Parameters
type (QVariant.Type) –
- setTypeName(self, typeName: str)¶
Set the field type.
- Parameters
typeName (str) – Field type
- staticMetaObject = <PyQt5.QtCore.QMetaObject object>¶
- subType(self) QVariant.Type ¶
If the field is a collection, gets its element’s type. When all the elements don’t need to have the same type, this returns QVariant.Invalid.
New in version 3.0.
- Return type
QVariant.Type
- type(self) QVariant.Type ¶
Gets variant type of the field as it will be retrieved from data source
- Return type
QVariant.Type
- typeName(self) str ¶
Gets the field type. Field types vary depending on the data source. Examples are char, int, double, blob, geometry, etc. The type is stored exactly as the data store reports it, with no attempt to standardize the value.
- Return type
str
- Returns
QString containing the field type