Lycia LowCode Methods

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Lycia LowCode Methods

Common information:

A method is a function associated with an object (or a class);
When a method belongs to a class, it defines behavior that instances (objects) of that class can exhibit;
If you access a method through an object, it acts as if it is "bound" to that specific instance, meaning it can access the object's data (properties or attributes) via THIS keyword.

Calling a method from the InteractForm object:

FUNCTION (this InteractForm) DoesTableRowExist(view STRING, vals REFERENCE) RETURNS BOOL

Calling a method from the View:

FUNCTION (this View) DoesTableRowExist(vals REFERENCE) RETURNS BOOL

Method	Purpose
DoesTableRowExist()	Used for querying the database about whether a row with a given primary key(s) value(s) exists
GetCurrentDialog()	Returns the dialog object (ui.Dialog) of the InteractForm object
GetEventView()	Returns the name of the view in which the event is currently running
GetEventSubInteraction()	Returns the name of the sub-interaction in which the event is currently running
GetCurrentEvent()	Returns the raw event name that was currently running
SaveChanges()	Used to store changes in the database
Refresh()	Used to reset data in the View
GetViewCurrentRecord()	Used to get the current record data of the View
SetViewCurrentRecord()	Used to modify the current record data of the View
GetViewArray()	Used to get the array data of the View
SetViewArray()	Used to set the array data of the View
SetEmbeddedData()	Allows a LowCode data source View to use data of a variable (array of records) handled / managed by your 4GL code instead of a database table

Rules of Usage

DISPLAY ARRAY:

The SetViewCurrentRecord() and SetViewArray() methods show modified / input data in the appropriate View;
The Save action will not commit modified data. You have to call the SaveChanges() method to commit new data to the database;
Scrolling doesn’t update the displayed data in the unbuffered mode. You have to call the SaveChanges() method to save data in the database, or call the Refresh() method of the View to reset data to the original (saved) data;
If case of using the buffered mode, scrolling will reset the displayed data to the original (saved) data;
If the SetViewCurrentRecord() and SetViewArray() methods were called when the DISPLAY ARRAY is in the Edit or Insert state (one row is currently in INPUT), then the new data will be displayed in this INPUT and can be stored / committed with the Save or Apply actions.

INPUT ARRAY:

The SetViewCurrentRecord() and SetViewArray() methods show modified / input data in the appropriate View;
The Save action will commit modified data;
Scrolling doesn’t update the displayed data in the unbuffered mode. You have to call the SaveChanges() method to save data in the database, or call the Refresh() method of the View to reset data to the original (saved) data;
If case of using the buffered mode, scrolling will reset the displayed data to the original (saved) data.

Additional Information

Lycia does not update the displayed data on scrolling to not cause a heavy load on performance. Yet, in the buffered mode, Lycia executes the ON BUFFER action, and the buffer data is reset and loaded from the database again;
To simulate resetting the original data on scrolling, you can bind the AFTER ROW action and call the Refresh() method of the appropriate View in it.

DoesTableRowExist()

This method is created to query the database on whether a row with a given primary key(s) value(s) does exist. The function DoesTableRowExist() is available as a public function and as a method of the view object.

Syntax:

1. Standalone public function:

FUNCTION DoesTableRowExist(table STRING, keys DYNAMIC ARRAY OF STRING, vals REFERENCE) RETURNS BOOL

table - the table name to be checked;
keys - the list of keys to be checked;
vals - is RECORD or HASHMAP with values to be checked.

2. Method of the Views object:

FUNCTION (this VIEW) DoesTableRowExist(vals REFERENCE) RETURNS BOOL

vals - is RECORD or HASHMAP with values to be checked.

Example code for a standalone public function:

#Query the table "state" if a row with a given set of primary key values exist.

LET hm["country"]= country

LET hm["state_code"]= state_code

#FUNCTION DoesTableRowExist(table STRING, keys DYNAMIC ARRAY OF STRING, vals REFERENCE) RETURNS BOOL

IF DoesTableRowExist("state", ["country,state_code"], hm) THEN

MESSAGE "Table row with the primary key values country and state_code does exist"

ELSE

ERROR "Table row with the primary key values country and state_code does not exist"

END IF

END FUNCTION

Example code for the Views method:

#Query the table "state" if a row with a given set of primary key values exist.

LET hm["country"]= country

LET hm["state_code"]= state_code

#FUNCTION (this VIEW) DoesTableRowExist(vals REFERENCE) RETURNS BOOL

IF iForm.views["state"].DoesTableRowExist(hm) THEN

MESSAGE "Table row with the primary key values country and state_code does exist"

ELSE

ERROR "Table row with the primary key values country and state_code does not exist"

END IF

END FUNCTION

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GetCurrentDialog()

The GetCurrentDialog() method is an instance method of the InteractForm and View objects:

# FUNCTION (this InteractForm) GetCurrentDialog() RETURNS Ui.Dialog

# FUNCTION (this View) GetCurrentDialog() RETURNS Ui.Dialog

Note: One instance of InteractForm can have one or many instances of View referenced / stored in the views Hashmap.

TYPE InteractForm RECORD #

form_file STRING # The form file that should be opened

, log_file STRING # The path to log file. It's optional property

, log_to_file BOOL # Indicates if error message should be logged to file

, translations HASHMAP OF STRING # Map of message/table/column translations

, views HASHMAP OF View # A set of views of tables that are depends each other

, custom VARIANT # The placeholder for any additional custom values that can be usefull to keep in object

END RECORD #

iForm.GetCurrentDialog() returns the dialog object (ui.Dialog) of the InteractForm object.

iForm.views["<table_name>"].GetCurrentDialog() returns the dialog object (ui.Dialog) of the specified View of an InteractForm object.

Example:

FUNCTION i_p_policy_actions_insert_after_field(iform InteractForm INOUT) RETURNS BOOL

DEFINE dlg ui.dialog

LET dlg = iForm.views["policy"].GetCurrentDialog()

LET field_id = dlg.getCurrentItem()

LET _rec_policy = iForm.views["policy"].GetViewCurrentRecord()

CASE dlg.getCurrentItem()

...

WHEN "policy.client_no"

IF _rec_policy.client_no < 1 OR _rec_policy.client_no IS NULL THEN

ERROR "Client Number can not be empty, 0 or negative"

CALL dlg.nextfield("+PREV")

END IF

...

END CASE

CALL iForm.views["policy"].SetViewCurrentRecord(iForm, _rec_policy)

RETURN FALSE

END FUNCTION

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GetEventView()

The public method GetEventView() returns the name of the view in which the event is currently running:

FUNCTION (this InteractForm) GetEventView() RETURNS STRING

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GetEventSubInteraction()

The public method GetEventSubInteraction() returns the name of the sub-interaction in which the event is currently running:

FUNCTION (this InteractForm) GetEventSubInteraction() RETURNS STRING

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GetCurrentEvent()

The method GetCurrentEvent() returns the raw event name that was currently running:

FUNCTION (this InteractForm) GetCurrentEvent() RETURNS STRING

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SaveChanges()

This method is used to store changes in the database (for the View object):

FUNCTION SaveChanges(iForm InteractForm INOUT)

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Refresh()

This method is used to reset the data in the View:

FUNCTION Refresh(iForm InteractForm INOUT, withQuestion BOOL) RETURNS BOOL

This method only works in the update mode (at the record modification, to revert the changes) or in the main interaction.

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GetViewCurrentRecord()

This method is used to get the current record data of the View:

GetViewCurrentRecord() RETURNS HASHMAP

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SetViewCurrentRecord()

This method is used to modify the current record data of the View:

SetViewCurrentRecord(iForm InteractForm INOUT, rec HASHMAP)

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GetViewArray()

This method is used to get the array data of the View:

GetViewArray() RETURNS DYNAMIC ARRAY OF HASHMAP

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SetViewArray()

This method is used to set the array data of the View:

SetViewArray(iForm InteractForm INOUT, arr DYNAMIC ARRAY OF HASHMAP)

Restrictions

The SetViewArray() method will show an error if it is used in the View with the buffered mode. The SetViewCurrentRecord() method can be used in any mode;
SetViewArray() will show an error if it is called for View with an embedded array variable. You have to use SetEmbeddedData() method instead;
SetViewArray() will show an error if it is called for View with unbuffered mode, the related database table doesn’t have a Primary Key, and the input data has a different size than the origin. It means that the input data contains new rows or deleted rows, and it is not possible to analyze what rows exactly are deleted and what rows are new.

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SetEmbeddedData()

This method allows a LowCode data source View to use data of a variable (array of records) handled / managed by your 4GL code instead of a database table.

It accepts the DYNAMIC ARRAY OF RECORD as the parameter:

CALL <settings_record>.views["<db_table_name>"].SetEmbeddedData(<array_name>)

The array members should have the same names as the form field Identifiers where the data will be displayed.

Example:

FUNCTION init_embedded_array_data()

LET _arr_rec_contact[1].cont_id = i

LET _arr_rec_contact[1].cont_fname = "Alex"

LET _arr_rec_contact[1].cont_lname = "Williams"

LET _arr_rec_contact[2].cont_id = i

LET _arr_rec_contact[2].cont_fname = "Angela"

LET _arr_rec_contact[2].cont_lname = "Hoelzl"

END FUNCTION

FUNCTION contact_activity_list(p_rec_settings InteractForm_Settings)

LET p_rec_settings.form_file = "../demo_contact_activity_embedded/contact_activity_list"

CALL init_embedded_array_data() #populate array record 'contact' with data

CALL p_rec_settings.views["contact"].SetEmbeddedData(_arr_rec_contact)

CALL InteractForm(p_rec_settings)

END FUNCTION

There are some specifics to this method's use:

The SetEmbeddedData() method only allows a DYNAMIC ARRAY OF RECORD. If you want to have a single INPUT there, you need to append one row to the local array and hide the events specific to an INPUT ARRAY such as Insert, Append, etc.;
The View with embedded data can not depend on another View, because Lycia LowCode can't make queries from the local array. But you can emulate it using a custom function for the event "BEFORE ROW" in the parent View and update the target View by calling the SetEmbeddedData method of the InteractForm object already populated with data, which is dependent on the selected row in the parent view;
The view with an embedded array always operates with the paged_mode: -1. It is done automatically by LowCode regardless of what is specified in the settings, because all the data is already available.

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