QtSql.QSqlField Class Reference

The QSqlField class manipulates the fields in SQL database tables and views. More...

Inheritance diagram for QtSql.QSqlField:

Collaboration diagram for QtSql.QSqlField:

Public Types
enum	RequiredStatus { Optional = 0, Required = 1, Unknown = -1 }
	More...

Public Member Functions
override bool	Equals (object o)
override int	GetHashCode ()
	QSqlField (QSqlField other)
	QSqlField (string fieldName="", QVariant.Type type=QVariant.Type.Invalid)
virtual void	CreateProxy ()
new void	Clear ()
new bool	IsAutoValue ()
new bool	IsGenerated ()
new bool	IsNull ()
new bool	IsReadOnly ()
new bool	IsValid ()
new void	SetAutoValue (bool autoVal)
new void	SetGenerated (bool gen)
new void	SetReadOnly (bool readOnly)
new void	SetRequired (bool required)
new void	SetSqlType (int type)
new int	TypeID ()
new void	Dispose ()

Static Public Member Functions
static bool	operator!= (QSqlField arg1, QSqlField arg2)
static bool	operator== (QSqlField arg1, QSqlField arg2)

Protected Member Functions
	QSqlField (System.Type dummy)

Protected Attributes
SmokeInvocation	interceptor

Properties
new object	DefaultValue [get, set]
new int	Length [get, set]
new string	Name [get, set]
new int	Precision [get, set]
new QSqlField.RequiredStatus	requiredStatus [get, set]
new QVariant.Type	Type [get, set]
new object	Value [get, set]
virtual System.IntPtr	SmokeObject [get, set]

Detailed Description

The QSqlField class manipulates the fields in SQL database tables and views.

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:

QSqlField field("age", QVariant::Int);

field.setValue(QPixmap()); // WRONG

However, the field will attempt to cast certain data types to the field data type where possible:

QSqlField field("age", QVariant::Int);

field.setValue(QString("123")); // casts QString to int

QSqlField objects are rarely created explicitly in application code. They are usually accessed indirectly through QSqlRecords that already contain a list of fields. For example:

QSqlQuery query;

...

QSqlRecord record = query.record();

QSqlField 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 QSqlRecord.

Member Enumeration Documentation

enum QtSql.QSqlField.RequiredStatus

Specifies whether the field is required or optional.

See also requiredStatus().

Enumerator:

Optional	The fields doesn't have to be specified when inserting records.
Required	The field must be specified when inserting records.
Unknown	The database driver couldn't determine whether the field is required or optional.

Constructor & Destructor Documentation

QtSql.QSqlField.QSqlField ( System.Type  dummy )

protected

QtSql.QSqlField.QSqlField

(

QSqlField

other

)

Constructs a copy of other.

QtSql.QSqlField.QSqlField	(	string	fieldName = "",
		QVariant.Type	type = QVariant.Type.Invalid
	)

Constructs an empty field called fieldName of variant type type.

See also setRequiredStatus(), setLength(), setPrecision(), setDefaultValue(), setGenerated(), and setReadOnly().

Member Function Documentation

new void QtSql.QSqlField.Clear

(

)

Clears the value of the field and sets it to NULL. If the field is read-only, nothing happens.

See also setValue(), isReadOnly(), and requiredStatus().

virtual void QtSql.QSqlField.CreateProxy ( )

virtual

new void QtSql.QSqlField.Dispose

(

)

override bool QtSql.QSqlField.Equals

(

object

o

)

override int QtSql.QSqlField.GetHashCode

(

)

new bool QtSql.QSqlField.IsAutoValue

(

)

Returns true if the value is auto-generated by the database, for example auto-increment primary key values.

See also setAutoValue().

new bool QtSql.QSqlField.IsGenerated

(

)

Returns true if the field is generated; otherwise returns false.

See also setGenerated(), type(), requiredStatus(), length(), precision(), and defaultValue().

new bool QtSql.QSqlField.IsNull

(

)

Returns true if the field's value is NULL; otherwise returns false.

See also value().

new bool QtSql.QSqlField.IsReadOnly

(

)

Returns true if the field's value is read-only; otherwise returns false.

See also setReadOnly(), type(), requiredStatus(), length(), precision(), defaultValue(), and isGenerated().

new bool QtSql.QSqlField.IsValid

(

)

Returns true if the field's variant type is valid; otherwise returns false.

static bool QtSql.QSqlField.operator!= ( QSqlField  arg1, QSqlField  arg2  )

static

Returns true if the field is unequal to other; otherwise returns false.

static bool QtSql.QSqlField.operator== ( QSqlField  arg1, QSqlField  arg2  )

static

Returns true if the field is equal to other; otherwise returns false.

new void QtSql.QSqlField.SetAutoValue

(

bool

autoVal

)

Marks the field as an auto-generated value if autoVal is true.

See also isAutoValue().

new void QtSql.QSqlField.SetGenerated

(

bool

gen

)

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.

See also isGenerated(), setType(), setRequiredStatus(), setLength(), setPrecision(), setDefaultValue(), and setReadOnly().

new void QtSql.QSqlField.SetReadOnly

(

bool

readOnly

)

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 isReadOnly().

new void QtSql.QSqlField.SetRequired

(

bool

required

)

Sets the required status of this field to Required if required is true; otherwise sets it to Optional.

See also setRequiredStatus() and requiredStatus().

new void QtSql.QSqlField.SetSqlType

(

int

type

)

new int QtSql.QSqlField.TypeID

(

)

Member Data Documentation

SmokeInvocation QtSql.QSqlField.interceptor

protected

Property Documentation

new object QtSql.QSqlField.DefaultValue

getset

Returns the field's default value (which may be NULL).

Sets the default value used for this field to value.

new int QtSql.QSqlField.Length

getset

Returns the field's length.

If the returned value is negative, it means that the information is not available from the database.

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.

new string QtSql.QSqlField.Name

getset

Returns the name of the field.

Sets the name of the field to name.

new int QtSql.QSqlField.Precision

getset

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.

Sets the field's precision. This only affects numeric fields.

new QSqlField.RequiredStatus QtSql.QSqlField.requiredStatus

getset

Returns true if this is a required field; otherwise returns false. An INSERT will fail if a required field does not have a value.

Sets the required status of this field to required.

virtual System.IntPtr QtSql.QSqlField.SmokeObject

getset

new QVariant.Type QtSql.QSqlField.Type

getset

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.

Set's the field's variant type to type.

new object QtSql.QSqlField.Value

getset

Returns the value of the field as a QVariant.

Use isNull() to check if the field's value is NULL.

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().