An example using a hidden prefilter field to show a table comment
We can use prefilter fields as data storage.
When opening the table via linkToData, we pass the value of the hidden prefilter field into the filter. And prefilter fields are accessible via #.
Let's display the table comment based on the prefilter field:
=: setTableFormat(tabletext: #fl_hidden_field)
An example of blocking the adding of rows using the prefilter field
For example, we have a table with cycles, and we want these cycles to be linked 1 to 1 with another table of cycles. These are orders and the invoices linked to them.
So, we need to, when transitioning from the order cycle, record its cycle number and keep this number when creating an invoice.
Also, we need to block the creation of invoices if the order number is empty.
Action code in the order:
=: linkToTable(table: 'bills'; filter: 'fl_order_num' = $#nci; target: "self")
When creating a cycle in Invoices, we take the #fl_order_num field in the row part and then take it inside the bill cycle because the table inside the cycle in bills will not have access to fl_order_num.
In the table formatting code for Invoices, we block the addition if fl_order_num is equal to "":
f1=: setTableFormat(condition: #fl_order_num = ""; blockadd: true)