Adding a form filter - forms

Question

I'm currently working on a form in Microsoft Dynamics AX.
The form consists of a grid with about 10 fields from 4 different tables.
As the form is now it returns too many values so I need to include some sort of filter, it doesn't need to be dynamic, just a static filter saying only show the lines with value X in column Y.
Has anyone here got some experience with this sort of thing? Where do I start?
I must say I'm not experienced with Microsof AX at all, I've been working with it for about a month now.
I've tried to follow this guide: How to: Add Filter Controls to a Simple List Form [AX 2012]
But I got stuck at the second part (To add a control to the custom filter group) Step 2: I dont know which type of control to chose, and ik i pick lets say a ComboBox i cant get Step 3 to work because I dont see the 'Override Methods' they mention.

Answer 1

Well, I usually do it this way:
In ClassDeclaration, create as many QueryBuildRanges variables as fields to filter. Let's name them Criteria1, Criteria2, etc (name them properly, please, not as here)
QueryBuildRange criteria1, criteria2;
In each Datasource you need to filter, override method Init, an add code similar to this:
super();
criteria1 = this.query().datasource(tablenum(tableofdatasource)).addQueryRange(fieldNum(fieldtofilter))
//criteria1.status(RangeStatus::locked); //optional - this way you can hide filter field to user, have it readonly for users, etc
Create a control of type StringEdit or ListBox in form to be used as filter. Change their AutoDeclaration property to Yes. Override modified() method. In it, I use to put something similar to:
super();
element.changeFilters();
In form, add method changeFilters();
range rangeFromStringControl = StringEditControlName.text(); //Put in rangeFromStringControl the string to be used as filter, as a user would write it
range rangeFromListBoxControl;
criteria1.value(rangeFromStringControl);
switch (listBoxControl.Selection())
{
case NoYesAll::All:
rangeFromListBoxControl = ''; //Empty filter string - No filter at all
break;
case NoYesAll::No:
rangeFromListBoxControl = QueryValue(NoYes::No); //Or whatever string filter value you want
break;
//Etc
}
//We have all filter strs done; let's filter for each main DataSource required with new filters
DataSource1.executeQuery();
//If there is other datasources joined to this one, it's usually no necessary to call their executeQuery;
//If there are others with filters and not joined to it, call their executeQuery()
If you need this filter to be applied when form is open, set appropiate initial values to controls, and then in form's run() method:
run();
element.changeFilters();