Dynamics AX Custom Lookup

As a Dynamics AX developer, you'll often have to perform custom lookups. Meaning that the user may only select records in another table depending on some condition on the form, or elsewhere.


There are two ways of creating custom lookups. I'll show the easiest here, and maybe show the other way in the future.

So if you're thinking you'll have to create a new form and all that, forget it, you won't. All you have to do is write some pieces of code.



First let's create our lookup method directly on the table. You can check other tables for these special lookup methods. They appear in lots of tables. Take for example the table ContactPerson. It has the following custom lookup methods by default:

• lookupActionContactPerson
• lookupCustContactPerson
• lookupDirContactPerson
• lookupDirContactPersionId
• lookupVendContactPerson

Now, to create a custom lookup, we'll use the class SysTableLookup as it provides us a set of methods to do so.


Here's our method, to be created directly on the table DummyTable, with some dummy data and names.

public client static void lookupDummyTable(FormStringControl _ctrl,
                                           MyFilterEDT _filter)
{
  
    // Intantiantes a SysTableLookup object telling it which control activated the lookup, and
    // what table should be displayed inside the lookup form.
    SysTableLookup sysTableLookup = SysTableLookup::newParameters(tablenum(DummyTable), _ctrl);

    Query query = new Query(); // This query will be used by the lookup form.
    QueryBuildDataSource qbds;

    ;

    // The "addLookupField" method adds the the fields that will be shown inside the lookup's grid. 
    // The second, boolean parameter indicates that this field will be returned from the lookup when a
    // record is selected. In this case, we'll return our DummyPK.
    sysTableLookup.addLookupField(fieldnum(DummyTable, DummyPK), true); 
    sysTableLookup.addLookupField(fieldnum(DummyTable, Field1));
    sysTableLookup.addLookupField(fieldnum(DummyTable, Field2));
    sysTableLookup.addLookupField(fieldnum(DummyTable, Field3));


    // Using our dummy table as a DataSource Table.
    qbds = query.addDataSource(tablenum(DummyTable));

    // This is the key part, what we want to filter to be displayed in the grid.
    qbds.addRange(fieldnum(DummyTable, MyFilterColumn)).value(_filter);


    // Passes the query to the sysTableLookup.
    sysTableLookup.parmQuery(query);

    // Activates the lookup.
    sysTableLookup.performFormLookup();
}

With that little piece of code, Dynamics AX will already display a lookup form with the table you've specified as a DataSource, displaying the fields you specified with the method addLookupField and following the results criteria of the Query you've passed to it.



Now all we have to do is actually call our lookup method, by overriding the lookup of the correct field in our Form's Data Source:

public void lookup(FormControl _formControl, str _filterStr)
{
    ;

    DummyTable::lookupDummyTable(_formControl, "SomeFilter");
}

And that's it! The lookup will be performed. But there's one additional step we'll have to take here...

When the user tries to select our DummyTable reference, Dynamics AX will display the results of the query, based on the filter we've created. So the user will only be able to see what we want him to see, and so he'll only be able to select what we want. The problem is that if he types in an existing record for the DummyTable in the control, even if does not get shown in our lookup, Dynamics AX will accept that. Remember: we're only limiting what the user may see and select for that field, but we're not limiting what he can actually type in the control. So if we don't validate it somehow, Dynamics AX will run the standard validation, which will only check if a record exists for that EDT and so on. To avoid that the user does in fact type in something we don't want, we'll have to override the validate method for our field in our Data Source. The simplest logic is to check if the DummyTable record the user typed in does attend the filter we've specified:

public boolean validate()
{
    DummyTable    dummyTable;

    ;

    dummyTable = DummyTable::find(currentRecord.DummyTableRefField);

    return dummyTable.MyFilterColumn == "SomeFilter";
    
}

So if the user simply types in for a record that does not attend our filter, Dynamics AX won't let the user save that value.



This is the easiest way to effectively implement a custom lookup and validate the user input in case he doesn't select the record from the lookup. For this example I used a literal filter, a string. But in most cases, you'll have to filter according to what the user selected for another field in your form. Things should usually be dynamic.

Hope this helps...

Refresh DataSource and retain position

Update: Also read "How to effectively refresh data on forms".

Refresh a DataSource is a very common task to Dynamics AX developers, as you'll most likely perform changes on a record and have to present it to the user, on a form.


The most commonly used method to refresh the DataSource to make a form show what you have changed on a record is the research method.
The only problem is that the research method doesn't retain the record that was selected, it positions the DataSource on the first record of the result, causing the user to see another record. To resolve this matter, the research method, only in Dynamics AX 2009, has a boolean parameter, retainPosition. Now if you call it by passing true to it, it will sure retain the position of the selected record after the refresh, right? Wrong...


This should only work when your form has DataSources linked by Inner Joins in it, what means that the generated query has Inner Joins in it. Having any other link types or temporary tables causes it to not retain the position, even if you pass true when calling it.

So I'll present you two ways of retaining the position of the selected record, one that works sometimes, and one that always works, although you should always try and see if it works with research(true) before trying anything else.


On the first way, you could simply get the position of the DataSource before calling research(), like this:

int position;

    ;

    position = myTable_ds.getPosition();
    myTable_ds.research();
    myTable_ds.setPosition(position);

But does this work perfectly? Not again...

The code above should select the record that was on the previously selected record's position. What does that mean? It means that if your query result changes the record's orders, you won't have the correct record selected. This could easily happen if your form handles the records' order in a special way, or if the action is performed when the record or any records are inserted, which will certainly cause the the form to reorder the records when you tell it to refresh the DataSource.


The second way to do it will actually look for the correct record and then select it, so you can imagine it will perform a little worse than the others, but at least it will never fail (unless you, somehow, delete the record you're looking for in the meantime).


Simply copy the RecId from the record you want to keep selected to a new table buffer, like this:

MyTable      myTableHolder;
    
    ;

    myTableHolder.RecId = myTableRecord.RecId;
    
    myTable_ds.research(); // or: myTableRecord.dataSource().research();

    myTable_ds.findRecord(myTableHolder); // or: myTableRecord.dataSource.findRecord(myTableHolder);     

We copy if to a new table buffer because the findRecord method expects a parameter of type Common. If you stored the RecId in a variable, you would have to pass it to a table buffer anyway...


And that's it, it'll first refresh the DataSource, and then look for your record and select it, so the screen might even "blink" for a second. As I said, this is not the best when thinking about performance, but at least it works...