Participating in the forum makes you aware of some things where members got some confusion and that is the reason why I decided to add this in my tutorials.  With this one, I will limit the topic to combobox to help us understand better how to manipulate things within it.  I said before with MDOT and NOFILTER articles,  if you will use one, at least you know why.  This time however, the purpose is if you will use a combobox, at least you know how.

One scenario with combobox that I recently encountered inside Foxite Forum is hiding of columns.  Sometimes you would want to include two RowSource but doesn’t want to show the 2nd one, right?  Problem is even if you put the 2nd column as 0, there will be a space shown for that column and that makes the combobox “ugly”.  Take a look at the image below:

Data:

Source code

CREATE CURSOR junk (Country c(20), CtyPK I)
INSERT INTO junk VALUES ("Philippines",1)
INSERT INTO junk VALUES ("America",2)
INSERT INTO junk VALUES ("Australia",3)
INSERT INTO junk VALUES ("Canada",4)

Settings:

Source code

.RowSource = "junk.Country,CtyPk"
.RowSourceType = 6
.ColumnCount = 2
.ColumnWidths = "100,0"

So the question is, why would you make the ColumnCount property as 2 if what you plan to show anyway is just the first column?  The solution to hiding it is retaining the columncount as 1:

Should be Settings:

Source code

.RowSource = "junk.Country,CtyPk"
.RowSourceType = 6
.ColumnCount = 1  && you don't want to show column 2 so make columncount 1
.ColumnWidths = "100"  && or just leave this and allow the combobox to automatically adjust the width based on field with, i.e., c(20)

Question now is if you don’t show the other column, will the data also disappear?

No!

Can we therefore still get the value from that missing column?

Of course, it is actually not missing.  It is just there but is hidden.  By default, value of combobox is binded to column1 or the first field of the RowSource property.  To tell VFP that what we want to get instead is the value of the hidden column, you simply have to change the BoundColumn property to your target column, be it hidden or shown.  So to get the value of column 2, all you need to do is:

Source code

.BoundColumn=2

And VFP will know that you are instructing it to get the value, not from the visible column, but from that hidden column of the RowSource property.

One thing I believe that is misunderstood about combobox’ RowSource and ColumnCount property is that those two, although works in harmony, is totally dependent of each other. No it is not.  You can create a number of fields as rowsource and create less or more than that as columns.   And it will still work or run without any error.

You have to analyze and realize that the reason why RowSource is in Data Tab is because it deals with data while ColumnCount is in Layout Tab as it deals with Appearance. You should not confuse yourself with the linkings VFP made between the two.

In the above image, I have shown how ColumnCount works when it is less than the number of fields in the RowSource.  Below I will show you that ColumnCount can have more columns than that of the fields of the RowSource:

Increasing Columns beyond RowSource fields:

Source code

.RowSource = "junk.Country,CtyPK"
.RowSourceType = 6
.ColumnCount = 5    && I make 5 columns here but RowSource only have two fields
.ColumnWidths = "100,100,100,100,100"

And here is what will happen based on the settings above:

Can we hide more than one column?

Yes we can, you can hide as many as you want but the minimum is 1 column because it needs something to drop to.

The reason why even though columns are hidden, we put those as part of RowSource fields is because we intend to use those.  Again, to get the values from the hidden columns, all you need to do is use the BoundColumn property.  So if we put:

Source code

this.RowSource = "mycursor.field1,field2,field3,field4,field5"
this.RowSourceType = 6
this.ColumnCount = 2

By default, value is binded to column1.  To get the value from a different column, shown or hidden, just change the BoundColumn as follows:

Source code

this.BoundColumn = 2   && gets the value of column2  (shown)
this.BoundColumn = 3   && gets the value of column3  (hidden because columncount = 2)
this.BoundColumn = 4   && gets the value of column4  (hidden)
this.BoundColumn = 5   && gets the value of column5  (hidden)

When I reduced the ColumnCount of the Combobox, it does not look good as the dropdown portion is shorter than the width of the combobox.  Can we increase the width of the dropdown portion?

Sure, you can for instance pad spaces to the right of the items of combobox by doing something like this:

Source code

.RowSource = "PADR(mycursor.country,50)"

How about making the width smaller than the source’s field’s width in case I have a very long width that does not look good on dropdown portion?

You can trim it via LEFT() function like:

Source code

.RowSource = "LEFT(mycursor.country,10)"

Can we get more than one value from a combobox at a time?

Yes we can.  Normally we get the value via Value property but there is one property that is again overlooked which is DisplayValue property.

What is this DisplayValue Property?

DisplayValue property specifies the contents of the first column of the selected item in a ListBox or ComboBox control.  Meaning if the value you wanted will come from the first column, then you can use that instead of the Value property.

Value and DisplayValue property will have the same result when BoundColumn is set to 1 (default).   Setting the BoundColumn property other than one will then enable you to get two values at the same time.

Source code

thisform.combo1.BoundColumn=2   && set this to the target column you want value to return
MESSAGEBOX(thisform.combo1.DisplayValue)   && This will always return value of column1
MESSAGEBOX(thisform.combo1.Value)          && this will always be based on BoundColumn property, in our sample here from column2

I hope that this simple tutorial will help clear up some confusions over the usage of combobox and I hope that this can guide you make your combobox appear neater.  Now go make your combobox presentation neater!