Filtering drop down list based on anothre drop down

Hello All,
I've come across a scenario where I have to select a value from a drop down and based on that value I have to fill another drop down. After I did it, I though it will be usefull for others as well. So, I am posting it here.
So, Here is what we need to do.
First create a contract class as (I am hoping) we already know. Here I am using an example of Customer which will be filtered by Customer group. The code of class declaration will be:

[

DataContractAttribute

]

public class custReportContract

{

    CustGroupId custGroup;

    AccountNum cust;

}

Now creating 2 new methods for getting and setting these parameters. 1 for cust group

[

DataMemberAttribute('CustGroup'),

SysOperationLabelAttribute(literalstr("@SYS11904"))

]

public CustGroupId parmCustGroup(CustGroupId _custGroup= custGroup)

{

    custGroup = _custGroup;

    return custGroup;

}

And the other one for customer

[

DataMemberAttribute('Cust'),

SysOperationLabelAttribute(literalstr("@SYS313797"))

]

public AccountNum parmCust(AccountNum _cust= cust)

{

    cust = _cust;

    return cust;

}

Your screen will look like this:

Nothing new in it. We all know it (I guess). Moving forward and now we are creating another class for UI builder.

Create this new class and on the class declaration method, type the following code

public class custReportUIBuilder extends SysOperationAutomaticUIBuilder

{

}

your screen will look like this

Now we have to create 2 dialog boxes. 1 for customer group and customer each. To do this type the following code.

    DialogField dialogCustGroup;

    DialogField dialogCust;

We also have to define our contract class here, so declare the contract class

    custReportContract contract;

so, the class declaration method will look like this:

public class custReportUIBuilder extends SysOperationAutomaticUIBuilder

{

    DialogField dialogCustGroup;

    DialogField dialogCust;

    custReportContract contract;

}

Now, we have to draw the dialog boxes. For this reason, we will create another method of build and type the following code In it.

public void build()

{

    Dialog      dialogLocal = this.dialog();

    custReportContract contract = this.dataContractObject();

   

    dialogLocal.addGroup("Customer");

    this.addDialogField(methodStr(custReportContract,parmCustGroup), contract);

    this.addDialogField(methodStr(custReportContract,parmCust), contract);

}

Now that we created the build method, let’s move into filling the cust group drop down with the table CustGroup. We’ll create another method for lookup and type the following code in it.

public void lookupCustGroup(FormStringControl _control)

{

    Query query = new Query();

    SysTableLookup sysTablelookup;

    sysTablelookup =SysTableLookup::newParameters(tableNum(CustGroup),_control);

    sysTablelookup.addLookupfield(fieldNum(CustGroup,CustGroup));

    sysTablelookup.addLookupfield(fieldnum(CustGroup,Name));

    query.addDataSource(tableNum(CustGroup));

    sysTablelookup.parmQuery(query);

    sysTablelookup.performFormLookup();

}

We need to create another method so that when user selects any record from cust group drop down, the customer drop down will be filtered with that value, for this reason we will select the modified event of cust group and then type the code:

public boolean custGroupModified(FormStringControl _control)

{

    dialogCustGroup.value(_control.valueStr());

    dialogCust.value('');

    return true

}

Ok now we will create the lookup method for customer. Here is the code

public void lookupCust(FormStringControl _control)

{

    Query query = new Query();

    SysTableLookup sysTablelookup;

    sysTablelookup =SysTableLookup::newParameters(tableNum(CustTable),_control);

    sysTablelookup.addLookupfield(fieldNum(CustTable,AccountNum));

    sysTablelookup.addLookupfield(fieldnum(CustTable,Party));

    query.addDataSource(tableNum(CustTable));

    query.dataSourceTable(tableNum(CustTable)).addRange(fieldNum(CustTable, CustGroup)).value(dialogCustGroup.value());

   

    sysTablelookup.parmQuery(query);

    sysTablelookup.performFormLookup();

}

Note that I filtered the cust query with the value selected in cust group drop down

    query.dataSourceTable(tableNum(CustTable)).addRange(fieldNum(CustTable, CustGroup)).value(dialogCustGroup.value());

we have almost completed our code for lookups and their filters. Now we will bind our dialog boxes with the contract class params and also override the modified method of cust group with the method we just wrote. To do this we will create another method for postBuild. Here we go

public void postBuild()

{

    super();

    // From binding info, get the dialog field for racecode attribute and add button

    dialogCustGroup = this.bindInfo().getDialogField(

                         this.dataContractObject(),

                         methodStr(custReportContract,parmCustGroup));

    if (dialogCustGroup)

    {

     dialogCustGroup.lookupButton(2);

    }

    // register override method for lookup cust Group

    dialogCustGroup.registerOverrideMethod(methodStr(FormStringControl, lookup), methodStr(custReportUIBuilder, lookupCustGroup), this);

    // register override method for modified

    dialogCustGroup.registerOverrideMethod(methodStr(FormStringControl, modified), methodStr(custReportUIBuilder, custGroupModified), this);

   

    //binding info for customer drop down

    dialogCust = this.bindInfo().getDialogField(

                         this.dataContractObject(),

                         methodStr(custReportContract,parmCust));

   

    // register override method for lookup customer

    dialogCust.registerOverrideMethod(methodStr(FormStringControl, lookup), methodStr(custReportUIBuilder, lookupCust), this);

   

    if (dialogCust)

    {

        dialogCust.lookupButton(2);

    }

}

We may have to create some other methods as well in order to functioning your code properly. They are getFromDialog, initializeFields and postRun. Create three new methods each for getFromDialog, initializeFields and postRun and copy the following code to them

public void getFromDialog()

{

    contract = this.dataContractObject();

    super();

}

public void initializeFields()

{

    contract = this.dataContractObject();

}

public void postRun()

{

    super();

}

We are done. But wait one last thing, open your contract class and in the class declaration method, reference your UI builder class just below the DataContractAttribute. Your code will become:

[

    DataContractAttribute,

    SysOperationContractProcessingAttribute(classStr(custReportUIBuilder))

]

public class custReportContract

{

    CustGroupId custGroup;

    AccountNum cust;

}

 We are now done. In this post we have tried to filter our single value drop down based on another drop down. In the next post we will try to repeat the same process for multi value drop down list.

Thank you all

Here is the screen shot of what we just did