Create lookup rule in Xbasic

[JarekZ]

Hello all,
I'm working on a little project that requires addition of one extra filed to a few tables. Additionally, the new field needs a simple lookup definition. I would like to accomplish that in a XBasic to simplify the deployment.
The only information I have found on this topic is here:
http://msgboard.alphasoftware.com/al...-Rule-W-xbasic
Thanks to Stan Mathew's reply I was able to come up with this code:

FUNCTION update_table AS C (tn as C, prefix as C )
	
	on error goto error_handler
	
	'create new columns
	dim fields as C =''
	 
	 fields = prefix +"_tax_type,c,4"+crlf()			
	 fields = fields+ prefix +"_tax_value,n,15,2"			
	
	table.Add_Fields(tn,fields)
	
   
	'set the lookup rule to tax_type
	dim rul as P
	dim t as P
	dim fType as P
	dim fGST as p
	dim fValue as p
	dim frul as P
	t = table.open(tn)
	rul = t.rules_get()
	
	rul.change_begin()
    	eval( "rul." + prefix+"_tax_type.lookup.Type = "+s_quote("Table"))
   	rul.change_end(.t.)

		
	rul.change_begin()
		eval( "rul." + prefix+"_tax_type.lookup.table_list.insert()")
		eval( "rul." + prefix+"_tax_type.lookup.Table = "+s_quote("lookup_tax.dbf"))
		eval( "rul." + prefix+"_tax_type.lookup.link = "+s_quote("Id"))
	rul.change_end(.t.)
		
	frul.table_list.insert()
	temp = frul.table_list.[1]
	temp.Condition = ""
	temp.Display = "No"
	temp.Fill = prefix +"_tax_type"
	temp.Source = "Id"
	temp.Width = 4
	
	frul.table_list.insert()
	temp = frul.table_list.[2]
	temp.Condition = ""
	temp.Display = "Yes"
	temp.Fill = ""
	temp.Source = "Name"
	temp.Width = 10

	
	t.close()
	
	error_handler:
    err = error_code_get()
    msg = error_text_get(err)
    ui_msg_box("Error", msg)
    t.close()
	end

END FUNCTION

Unfortunately it doesn't work. I'm getting an error that the 'rul.column_name.lookup' property does not exist. However when I try this code in the interactive window I'm able to add the lookup rule successfully:

t = table.open('table_name')
rul = t.rules_get()
rul.change_begin()
 rul.col_name.lookup.Type = "Table"
 rul.col_name.lookup.Table ="My_Lookup_table"
 rul.col_name.lookup.Link "ID";
rul.change_end(.t.)

 rul.col_name.lookup.table_list.insert()
rul.col_name.lookup.table_list.[1].Source = "Name"
rul.col_name.lookup.table_list.[1].Display = "Yes"

Can anybody explain why does it work in the interactive window, but doesn't inside the function? What is missing in that function to make it work?
Any help is greatly appreciated!
Thanks,
Jarek

[Stan Mathews]

Re: Create lookup rule in Xbasic

It has been a whiile since I delved into this area. I see you dimmed frul as P and used that pointer in

frul.table_list.insert()

Where do you assign something to this pointer?

[JarekZ]

Re: Create lookup rule in Xbasic

Thanks for the super fast reply! You are right - that might cause some problems down the line, but for now I'm not even getting that far. The code crashes on that line:
eval( "rul." + prefix+"_tax_type.lookup.Table = "+s_quote("lookup_tax.dbf"))

although this code runs successfully:
rul.change_begin()
eval( "rul." + prefix+"_tax_type.lookup.Type = "+s_quote("Table"))
rul.change_end(.t.)

it seems like it has no effect on the table/filed.
Thanks!

[JarekZ]

Re: Create lookup rule in Xbasic

Problem Solved!

As I said in the post above, this line
eval( "rul." + prefix+"_tax_type.lookup.Type = "+s_quote("Table"))
seems to have no effect - well that is precisely what happens - the code above did not assign the value to the property, it basically evaluated the statement (is property equal to this value) and returned false! To work around this i had to do this

 temp = eval( "rul." + prefix+"_tax_type.lookup") 'this will return the pointer to lookup property
 temp.Type = "Table" 'this will assign the value to the property

rest of the code needs adequate changes.

I have enough of Alpha for one day, but if somebody is interested please post here and I can publish the final working version of my function!

[Stan Mathews]

Re: Create lookup rule in Xbasic

Glad you found a solution. I think this would also work

eval( "rul." + prefix+"_tax_type.lookup.Type") = "Table"

or

evaluate_template( "rul." + prefix+"_tax_type.lookup.Type = "+s_quote("Table"))