Dynamic Column Headings

Description

The following technique shows how to display dynamic column headings in a grid component. The key to doing this is realizing that any property of a component can be overwritten before the component is executed. For example, the following is the code in the <head> section of a .a5w page that contains a component. All of the code shown in blue is code that is automatically inserted by the Web Component Builder when you insert a component on a page. (This is just a portion of the code.)

<%a5 
 Delete Tmpl 
 DIM Tmpl as P 
 tmpl = a5w_load_component("dv") 
 'Following code allows you to override settings in the saved component, and specify the component alias (componentName property). 
 'Tip: Keep the componentName property short because this name is used in page URLs, and it will help keep the URLs short. 
 'Each component on a page must have a unique alias (componentName property). 
 with tmpl 
 componentName = "dv" 
 field_info1.column.heading = "wow, this works"

end with

Note that the second to last line overwrites the column.heading property for column 1 in the grid. When the grid displays, it will show "wow, this works" and not the standard field label. Using this concept, it is easy to write a function that takes two arguments:

the name of an array (in this case the field_info array)
a dot variable that contains information about the field labels you want to override

One of the problems with this technique is that you override settings in the field_info[] array directly. If you change the order of the fields in the grid, the code to override settings will fail. Below is a generalized technique that you can you to override settings by "fieldname" rather than by field index. First, you would have to put this helper function on your page. you could use an A5W_INCLUDE() to include the helper function.

function override_array_setting as V ( input_a as P, override as C )

dim count as N

dim i as N

dim type as C
 
count = line_count(override) 
 delete override_a 
 dim override_acount as P
 
override_a.initialize_properties("fieldname|property|value", override) 
 count = override_a.first_empty()- 1 
 if (count > 0) then 
 for i = 1 to count 
 indx = input_a.find(ut(override_ai.fieldname), "ut(fieldname)") 
 if (indx > 0) then 
 type = typeof( eval("input_a" + indx + "." + override_ai.property 
 eval("input_a"+indx+"." + override_ai.property) = convert_type(override_ai.value,type) 
 end if 
 next i 
 end if
 
end function

In the place where you override settings, you would use the following example Xbasic.

dim override as C
 
override = <<%txt% 
 lastname|column.heading|LAST NAME 
 lastname|column.hide|.t. 
 customer_id|column.heading|Cust# 
 %txt% 

 override_array_setting(field_info, override)

In the string, override you are specifying the properties that you want to override using the syntax: fieldname|propertyname|newpropertyvalue . You can test this out by running the following script. First, the code created by the Web Component Builder.

dim tmpl as P
 
tmpl.ComponentName = "Component1" 
 tmpl.ComponentType = "Grid" 
 tmpl.DataSourceType = "DBF" 
 tmpl.DBF.type = "Table" 
 tmpl.DBF.table_name = "c:\program files\a5v6\samples\alphasports\Customer.Dbf" 
 tmpl.DBF.filter = "" 
 tmpl.DBF.order = "" 
 tmpl.DBF.flags = "" 
 tmpl.DBF.fieldmap = <<%str% 
 CUSTOMER_ID,C,8,0=Customer_id 
 FIRSTNAME,C,20,0=Firstname 
 LASTNAME,C,20,0=Lastname 
 COMPANY,C,32,0=Company 
 PHONE,C,20,0=Phone 
 FAX,C,20,0=Fax 
 BILL_ADDRESS_1,C,40,0=Bill_address_1 
 BILL_ADDRESS_2,C,40,0=Bill_address_2 
 BILL_CITY,C,20,0=Bill_city 
 BILL_STATE_REGION,C,20,0=Bill_state_region 
 BILL_POSTAL_CODE,C,10,0=Bill_postal_code 
 BILL_COUNTRY,C,20,0=Bill_country 
 SHIP_ADDRESS_1,C,40,0=Ship_address_1 
 SHIP_ADDRESS_2,C,40,0=Ship_address_2 
 SHIP_CITY,C,20,0=Ship_city 
 SHIP_STATE_REGION,C,20,0=Ship_state_region 
 SHIP_POSTAL_CODE,C,10,0=Ship_postal_code 
 SHIP_COUNTRY,C,20,0=Ship_country 
 SHIP_SAME,L,1,0=Ship_same 
 EMAIL,C,60,0=Email 
 %str% 

 tmpl.EditRegion.Grid.Top = <<%txt% 
 %txt% 
 tmpl.EditRegion.Grid.Bottom = <<%txt% 
 %txt% 
 tmpl.EditRegion.Grid.Left = <<%txt% 
 %txt% 
 tmpl.EditRegion.Grid.Right = <<%txt% 
 %txt% 

 tmpl.fields = 3 
 dim tmpl.field_infotmpl.fields as P
 
with tmpl.field_info1 
 fieldname = "Customer_Id" 
 Scope = "Local" 
 DisplayFormat = "" 
 DisplayUnFormat = "" 
 Type = "C" 
 controltype = "Label" 
 Label.InLineStyle = "" 
 Column.Hide = .f. 
 Column.Heading = "Customer id" 
 Column.Sort = "Customer_id" 
 end with
 
with tmpl.field_info2 
 fieldname = "Firstname" 
 Scope = "Local" 
 DisplayFormat = "" 
 DisplayUnFormat = "" 
 Type = "C" 
 controltype = "Label" 
 Label.InLineStyle = "" 
 Column.Hide = .f. 
 Column.Heading = "Firstname" 
 Column.Sort = "Firstname" 
 end with
 
with tmpl.field_info3 
 fieldname = "Lastname" 
 Scope = "Local" 
 DisplayFormat = "" 
 DisplayUnFormat = "" 
 Type = "C" 
 controltype = "Label" 
 Label.InLineStyle = "" 
 Column.Hide = .f. 
 Column.Heading = "Lastname" 
 Column.Sort = "Lastname" 
 end with
 
tmpl.style_name = "Barbie" 

 dim override as C
 
override = <<%txt% 
 lastname|column.heading|LAST NAME 
 lastname|column.hide|.t. 
 customer_id|column.heading|Cust# 
 %txt% 

 with tmpl 
 override_array_setting(field_info, override) 
 end with 

 ui_msg_box("", tmpl.field_info3.column.heading) 
 ui_msg_box("", "" + tmpl.field_info3.column.hide) 
 ui_msg_box("", tmpl.field_info1.column.heading)
 




function override_array_setting as V (input_a as P, override as C)

dim count as N

dim i as N

dim type as C
 
count = line_count(override) 
 delete override_a 
 dim override_acount as P
 
override_a.initialize_properties("fieldname|property|value", override) 
 count = override_a.first_empty()- 1
 
if (count > 0) then 
 for i = 1 to count 
 indx = input_a.find(ut(override_ai.fieldname), "ut(fieldname)") 
 if (indx > 0) then 
 type = typeof(eval("input_a" + indx + "." + override_ai.property) ) 
 eval("input_a"+indx+"." + override_ai.property) = convert_type(override_ai.value,type) 
 end if 
 next i 
 end if
 
end function

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