[Answers] Grid-3

[josipradnik]

Q:
Is there an attribute I can set to create a column calculation such as sum or average, etc?
A:
Grid column subtotals were added in Lianja v1.1.3. You can perform both horizontal and vertical totaling using NoCode.

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You can hide and show a grid section dynamically using Lianja.getElementByID("page1.section1").hide() or show().

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In the v1.3 release I have implemented "MultiSelect rows" for grids.
There are two new attributes for grid and attachment sections.
"MultiSelect rows"
and
"MultiSelect row expression"
Together with a new delegate called "SelectionChanged".
If you check "MultiSelect rows" in the grid section attributes then the first column of the grid contains a checkbox for each row. Clicking the checkbox calls the "SelectionChanged" delegate passing it a comma separated list of items that are evaluated for each row selected based on the "MultiSelect row expression".
This provides the ability to select multiple rows in a grid then perform an operation on them (section menu of other action) such as send an email or delete the records, then refresh the grid.

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In v1.2.4 I have added the ability to dynamically sort the data displayed in a grid by clicking on the grid column headers. This is implemented in both desktop and web clients. There is a new grid section attribute "Sortable" which you can check to enable this on a grid.
Here is an example in the Web Client. Just click the column header once to sort ascending and again to sort descending. This is all handled automatically for you and the grid is refreshed while still maintaining the parent->child relationship, filters and search condition if active.



To make a grid "Sortable" just check the "Sortable" attribute in the section attributes,

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Q:
I am struggling to find info on this, my grid has Price and Quantity columns and I want to add a Total column:
1. Must I have a db column that is marked as calculated? if so, does this column need to be created in code because I don't see anything in the ide column editor to indicate that the column is calculated.
2. If I don't have a calculated db column, can I just have a column grid column? if so, where do I enter the formula?
I guess I may need something like PRODUCT.PRICE*PRODUCT.QUANTITY in 'Get Data Mapping' but that has no effect.
A:
Just add a column and put the expression as the data source.
Set other columns that affect this new "calculated" column to "Recalculate" and its all done for you.
The "Grid formatting" example App demonstrates this.

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Q:
We can change the RecordSource of a grid no problem but removing the columns & starting again seems more difficult.
we can use ogrid.removecolumn(ColumnNo) in a loop to remove the columns but when the RecordSource is changed to a new value, the original columns headers & number of columns return.
How can we get the grid to re-read the column headers in the way that happens when the grid is first created?
A:
Then try clear() on the grid.

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Q:
In our app (at the customers request), we have 14 grid gadgets in 7 form sections (2 per section), populated by 14 READWRITE SQL cursorsA
The prg does the SQL & all works fine. The cursors are populated. Logic for the grids, called at each pass through the logic, is :

SELECT * from xxx WHERE xxx INTO CURSOR zzz READWRITE
oGrid = Lianja.Get("Page.section").GadgetGrid
oGrid.RecordSourceType = 4
oGrid.RecordSource = "zzz"
oGrid.Refresh()

The SQL always produces data for each cursor.
All of the above is so simple and works beautifully SOMETIMES. Sometimes the grids work great, sometime some of them are blank, sometimes they are not. Sometimes they the blank ones are populated & sometimes the populated ones go blank. This is ridiculous.
These grid gadgets really only want tables and when they are blank they error by saying no such table. We have tried every permutation of RecordSourceType and RowSourceType.
A:
yes I do understand the way VFP devs like using cursors like that but that does not work web/mobile client/server so I'll look and see what you are doing first.
There should be no issue with Lianja closing cursors unless you are selecting into the same cursor name in which case it behaves just like VFP.
it seems that what you want to do is choose multiple items in a list by checking the checkbox in the first column.
what happens as you do that? Does that cause you to perform a query on another grid? Then iterate this process on the child grids...?
i think this is where the design needs looked at.
what you need is a top level parent form e.g. Job#
this then relates to the child table that has records added to it for the job. This then will work multiuser and in the web / mobile.
The trick is to add all the related child records when you create a new job# or proposal# and these can be done in an insert trigger. They are related by job# so you have one child table with all the multiple choices as records.
This is then properly relational and can be properly queried by "joining" the tables together and displaying the related data in the UI.
this will allow you to design the app as form -> grid -> grids and the Lianja engine will do all the heavy lifting.
and all that will work in web/mobile.

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All topics in [Answers] alphabetically: http://www.lianja.com/community/show...ll=1#post12352
This same topic is extended to another thread: http://www.lianja.com/community/show...Answers-Grid-1
...and another thread (dont ask why): http://www.lianja.com/community/show...Answers-Grid-2