QGIS API Documentation  2.17.0-Master (f49f7ce)
Public Member Functions | Properties | List of all members
QgsField Class Reference

Encapsulate a field in an attribute table or data source. More...

#include <qgsfield.h>

Public Member Functions

 QgsField (const QString &name=QString(), QVariant::Type type=QVariant::Invalid, const QString &typeName=QString(), int len=0, int prec=0, const QString &comment=QString())
 Constructor. More...
 
 QgsField (const QgsField &other)
 Copy constructor. More...
 
virtual ~QgsField ()
 Destructor. More...
 
QString alias () const
 Returns the alias for the field (the friendly displayed name of the field ), or an empty string if there is no alias. More...
 
QString comment () const
 Returns the field comment. More...
 
bool convertCompatible (QVariant &v) const
 Converts the provided variant to a compatible format. More...
 
QString defaultValueExpression () const
 Returns the expression used when calculating the default value for the field. More...
 
QString displayName () const
 Returns the name to use when displaying this field. More...
 
QString displayString (const QVariant &v) const
 Formats string for display. More...
 
bool isNumeric () const
 Returns if this field is numeric. More...
 
int length () const
 Gets the length of the field. More...
 
QString name () const
 Returns the name of the field. More...
 
 operator QVariant () const
 Allows direct construction of QVariants from fields. More...
 
bool operator!= (const QgsField &other) const
 
QgsFieldoperator= (const QgsField &other)
 Assignment operator. More...
 
bool operator== (const QgsField &other) const
 
int precision () const
 Gets the precision of the field. More...
 
void setAlias (const QString &alias)
 Sets the alias for the field (the friendly displayed name of the field ). More...
 
void setComment (const QString &comment)
 Set the field comment. More...
 
void setDefaultValueExpression (const QString &expression)
 Sets an expression to use when calculating the default value for the field. More...
 
void setLength (int len)
 Set the field length. More...
 
void setName (const QString &name)
 Set the field name. More...
 
void setPrecision (int precision)
 Set the field precision. More...
 
void setType (QVariant::Type type)
 Set variant type. More...
 
void setTypeName (const QString &typeName)
 Set the field type. More...
 
QVariant::Type type () const
 Gets variant type of the field as it will be retrieved from data source. More...
 
QString typeName () const
 Gets the field type. More...
 

Properties

QString alias
 
QString comment
 
QString defaultValueExpression
 
bool isNumeric
 
int length
 
QString name
 
int precision
 

Detailed Description

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.

Definition at line 44 of file qgsfield.h.

Constructor & Destructor Documentation

QgsField::QgsField ( const QString name = QString(),
QVariant::Type  type = QVariant::Invalid,
const QString typeName = QString(),
int  len = 0,
int  prec = 0,
const QString comment = QString() 
)

Constructor.

Constructs a new QgsField object.

Parameters
nameField name
typeField variant type, currently supported: String / Int / Double
typeNameField type (eg. char, varchar, text, int, serial, double). Field types are usually unique to the source and are stored exactly as returned from the data store.
lenField length
precField precision. Usually decimal places but may also be used in conjunction with other fields types (eg. variable character fields)
commentComment for the field

Definition at line 46 of file qgsfield.cpp.

QgsField::QgsField ( const QgsField other)

Copy constructor.

Definition at line 52 of file qgsfield.cpp.

QgsField::~QgsField ( )
virtual

Destructor.

Definition at line 70 of file qgsfield.cpp.

Member Function Documentation

QString QgsField::alias ( ) const

Returns the alias for the field (the friendly displayed name of the field ), or an empty string if there is no alias.

See also
setAlias()
Note
added in QGIS 2.18
QString QgsField::comment ( ) const

Returns the field comment.

bool QgsField::convertCompatible ( QVariant v) const

Converts the provided variant to a compatible format.

Parameters
vThe value to convert
Returns
True if the conversion was successful

Definition at line 208 of file qgsfield.cpp.

QString QgsField::defaultValueExpression ( ) const

Returns the expression used when calculating the default value for the field.

Returns
expression evaluated when calculating default values for field, or an empty string if no default is set
Note
added in QGIS 2.18
See also
setDefaultValueExpression()
QString QgsField::displayName ( ) const

Returns the name to use when displaying this field.

This will be the field alias if set, otherwise the field name.

See also
name()
alias()
Note
added in QGIS 2.18

Definition at line 89 of file qgsfield.cpp.

QString QgsField::displayString ( const QVariant v) const

Formats string for display.

Definition at line 188 of file qgsfield.cpp.

bool QgsField::isNumeric ( ) const

Returns if this field is numeric.

Any integer or floating point type will return true for this.

Note
added in QGIS 2.18
int QgsField::length ( ) const

Gets the length of the field.

Returns
int containing the length of the field
QString QgsField::name ( ) const

Returns the name of the field.

See also
setName()
displayName()
QgsField::operator QVariant ( ) const
inline

Allows direct construction of QVariants from fields.

Definition at line 216 of file qgsfield.h.

bool QgsField::operator!= ( const QgsField other) const

Definition at line 79 of file qgsfield.cpp.

QgsField & QgsField::operator= ( const QgsField other)

Assignment operator.

Definition at line 64 of file qgsfield.cpp.

bool QgsField::operator== ( const QgsField other) const

Definition at line 74 of file qgsfield.cpp.

int QgsField::precision ( ) const

Gets the precision of the field.

Not all field types have a related precision.

Returns
int containing the precision or zero if not applicable to the field type.
void QgsField::setAlias ( const QString alias)

Sets the alias for the field (the friendly displayed name of the field ).

Parameters
aliasfield alias, or empty string to remove an existing alias
See also
alias()
Note
added in QGIS 2.18

Definition at line 177 of file qgsfield.cpp.

void QgsField::setComment ( const QString comment)

Set the field comment.

Definition at line 157 of file qgsfield.cpp.

void QgsField::setDefaultValueExpression ( const QString expression)

Sets an expression to use when calculating the default value for the field.

Parameters
expressionexpression to evaluate when calculating default values for field. Pass an empty expression to clear the default.
Note
added in QGIS 2.18
See also
defaultValueExpression()

Definition at line 167 of file qgsfield.cpp.

void QgsField::setLength ( int  len)

Set the field length.

Parameters
lenLength of the field

Definition at line 148 of file qgsfield.cpp.

void QgsField::setName ( const QString name)

Set the field name.

Parameters
nameName of the field

Definition at line 133 of file qgsfield.cpp.

void QgsField::setPrecision ( int  precision)

Set the field precision.

Parameters
precisionPrecision of the field

Definition at line 152 of file qgsfield.cpp.

void QgsField::setType ( QVariant::Type  type)

Set variant type.

Definition at line 138 of file qgsfield.cpp.

void QgsField::setTypeName ( const QString typeName)

Set the field type.

Parameters
typeNameField type

Definition at line 143 of file qgsfield.cpp.

QVariant::Type QgsField::type ( ) const

Gets variant type of the field as it will be retrieved from data source.

Definition at line 97 of file qgsfield.cpp.

QString QgsField::typeName ( ) const

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.

Returns
QString containing the field type

Definition at line 102 of file qgsfield.cpp.

Property Documentation

QString QgsField::alias
readwrite

Definition at line 53 of file qgsfield.h.

QString QgsField::comment
readwrite

Definition at line 51 of file qgsfield.h.

QString QgsField::defaultValueExpression
readwrite

Definition at line 54 of file qgsfield.h.

bool QgsField::isNumeric
read

Definition at line 48 of file qgsfield.h.

int QgsField::length
readwrite

Definition at line 49 of file qgsfield.h.

QString QgsField::name
readwrite

Definition at line 52 of file qgsfield.h.

int QgsField::precision
readwrite

Definition at line 50 of file qgsfield.h.


The documentation for this class was generated from the following files: