taqlwidget - Constructor

Description
This constructor creates the widget from the given description. The widget runs asynchronously as a subsequence. When the user presses the Go or Cancel button a returns event is generated which gives a record containing the fields select, where, orderby, and giving. These fields represent the four parts of a full TaQL command. All fields are empty if the Cancel button was pressed.

The constructor fails if no GUI is active in the system.

The argument cdesc determines the columns to be shown. It is a record in which each field describes a column. The field name is the column name; the field value is a record from which the following fields are used (if present):

valueType defines the type. Possible values are string, integer, float, double, complex, dcomplex, and boolean. Its main use is in building the help info.
If the type is string a value is enclosed in quotes if necessary.
istime defines if the field contains a date/time (defaults to F). If so, some extra operations will be added automatically to handle the date/time correctly. If the valueType is string, the DATETIME function is applied to the field to convert the string to a date/time. Otherwise the field is a numeric date/time in seconds and is divided by 24*3600 to convert it to days. The MJD function is applied to the value to convert it to a double value.
ndim defines the dimensionality of an array where 0 or -1 indicates any dimensionality. If the field is not present, the column is a scalar. It is only used in building the help info.
shape defines the fixed shape of arrays in a column. It is only used in building the help info.
comment can be used to give some extra information about the column. It is only used in building the help info.
labels defines the possible values for the column if it is known that the column can only have a limited number of values. Those values are shown in an optionmenu where the user can select from. It should be a vector of type valueType.
labelnames gives symbolic names for the possible values defined in labels. They are also shown in the optionmenu. They are only used if labels is given and if both vectors have the same length.

The table description returned by table.getdesc() is a record with the fields shown above. Only the fields istime, labels, and labelnames are not part of it. It means that a table description can directly be used in the taqlwidget constructor.

The description can contain as many fields as one likes. When more fields than the widget heigth (argument height) are given, a vertical scrollbar is added which can be used to scroll through all fields.

The arguments canSomething determine if the user is allowed to build a select string, sort string, and giving string. If so, the widget is extended with the appropriate entry boxes, etc. to make it possible.

Arguments

cdesc	in	The column descriptions
		Allowed:	Record
title	in	Title string
		Allowed:	String
		Default:	Query Dialogue
canselect	in	Possible to build select string?
		Allowed:	Bool
		Default:	F
cansort	in	Possible to build sort string?
		Allowed:	Bool
		Default:	F
cangiving	in	Possible to build giving string?
		Allowed:	Bool
		Default:	F
heigth	in	Height of the field list
		Allowed:	integer
		Default:	12
giving	in	default giving string
		Allowed:	string
		Default:	''
widgetset	in	widgetset to be used
		Allowed:	widgetset tool
		Default:	dws

Returns
subsequence

Example

include 'table.g'
include 'taqlwidget.g'
t := table('3C273XC1.MS');
q := taqlwidget(t.getdesc(), cansort=T);
await q->returns;
rec := $value;
t1 := t.query (rec.where, rec.giving, rec.orderby, rec.select);

Please note that the table.query() function supports taqlwidget directly (in synchronous mode). The above example could have been written in a much easier way as:

include 'table.g'
t := table('3C273XC1.MS');
t1 := t.query (unset);

Next: twodactionoptionmenu - Tool Up: taqlwidget - Tool Previous: taqlwidget - Tool Contents Index

	Package	display
	Module	widgets
	Tool	taqlwidget