In the examples above, the contents are entered at design time. They are static. Chances are, you need to populate the list box dynamically at run-time, by reading an OpenInsight table.
For this example, we use a simple database called KNOWLEDGE_BASE with three columns: RECORD_NUM, PRODUCT, TYPE, and TITLE. Do the following
Create this table, with RECORD_NUM as the key, and PRODUCT, TYPE, and TITLE as non-key fields.
Create a form to add the following 5 records:
RECORD_NUM | PRODUCT | TYPE | TITLE |
1 | OpenInsight | Tech Note | Hierarchical List Boxes Part 1 |
2 | OpenInsight | Tech Note | Hierarchical List Boxes Part 2 |
3 | OpenInsight | White Paper | How to Get to the Web with OpenInsight |
4 | Advanced Revelation | Tech Note | Using the NLM With Advanced Revelation |
5 | Advanced Revelation | White Paper | Converting Your Advanced Revelation Application to OpenInsight |
Put a BTREE index on RECORD_NUM, PRODUCT, and TYPE.
To populate the list box, create a function called TEST_LBD(). Copy the following code:
subroutine test_lbd (VOID) declare subroutine btree.extract, set_property, send_message, Msg equ PRODUCT$ to 1 equ TYPE$ to 2 equ TITLE$ to 3 **Setup a Btree.Extract routine to get all the data in the table** **This search_string passed to Btree.Extract will get all the records** search_string = "RECORD_NUM":@VM:">0":@FM table = "KNOWLEDGE_BASE" **Open the associated dictionary file for KNOWLEDGE_BASE** open "DICT.":table TO @DICT else Msg(@WINDOW , "Could not open the Dictionary for KNOWLEDGE_BASE") return end keys = '' ;*Keys is what the list of keys is returned to option = '' ;*No options are specified to send to Btree.Extract flag = '' ;*No flags are set to send to Btree.Extract Btree.Extract (search_string, table, @DICT, keys, option, flag) **Get the number of keys returned by Btree.Extract iKeyCount = count(keys,@VM) + (len(keys)>0) convert @VM to @FM in keys **Open the table so we can go through it to get the information for the list box** open 'KNOWLEDGE_BASE' to hKNOWLEDGE_BASE else Msg(@WINDOW , "Could not open the KNOWLEDGE_BASE table in Populate click event") return end content = '' ;*This will hold the information from the table to put in the list box. list = '' ;*This will hold a list of Products to ensure they do not repeat in the list view. iContPos = 0 ;*Increments the position of the information in the CONTENT variable. for i = 1 to iKeyCount read RECORD from hKNOWLEDGE_BASE, keys<i> else call msg(@WINDOW , "Couldn’t read from KNOWLEDGE_BASE table in the loop") end ** This will be true only the first time in the loop ** if i = 1 then /*List is going to be an @FM delimited list of all the products that were found. It will be used later to locate products in to ensure that they only show a specific product once. iContPos is the variable that holds which position the information will be in, in the list box */ iContPos = iContPos + 1 content<iContPos> = RECORD<PRODUCT$> list = RECORD<PRODUCT$> ** getAllTypes will get all the info according to RECORD<DATE$> ** gosub getAllTypes end else ** Checking to see if the product is in the list of products ** locate RECORD<PRODUCT$> In list Using @FM Setting POS then /* This Last Name is already there so don't add it to the content again */ end else iContPos = iContPos + 1 content<iContPos> = RECORD<PRODUCT$> list = list:@FM:RECORD<PRODUCT$> /* getAllTypes will get all the types according to RECORD<PRODUCT$>, which is Last Name in this case */ gosub getAllTypes end end next I /* All of the info has been retreived in the variable 'CONTENT', so now display it */ Set_Property(@WINDOW : '.LB_H', 'LIST', content) ** This code colapses the Hierarchical List Box ** Send_Message(@WINDOW : '.LB_H', 'EXPAND', 0, 0) ****************** getAllTypes: /* These parameters will be passed to Btree.Extract to get all the TYPES according to the PRODUCT of the current record Only get the records that are associated with the product that the record is on */ search_string = "PRODUCT":@VM:"=":Record<PRODUCT$>:@FM table = "KNOWLEDGE_BASE" Open "DICT.":table To @DICT Else Msg(@WINDOW , "Could not open KNOWLEDGE_BASE in the subroutine in the populate click") return End keysSub = '' optionSub = '' flagSub = '' list2 = '' ;*Going to hold the list of TYPES that will be searched to make ;*sure a TYPE doesn't get repeated in the list /* IF Btree.Extract is successful, the variable keysSub holds the list of keys, @VM delimited */ Btree.Extract(search_string, table, @DICT, keysSub, optionSub, flagSub) **Get the number of keys returned by Btree.Extract iKeyCountSub = count(keysSub,@VM) + (len(keysSub)>0) convert @VM to @FM in keysSub open 'KNOWLEDGE_BASE' to hKNOWLEDGE_BASE else Msg(@WINDOW , "Could not open the table 'KNOWLEDGE_BASE'") return end /* If iKeyCountSub is empty then there are no matching criteria for the search so the loop will not be executed */ for n = 1 to iKeyCountSub read RECORD from hKNOWLEDGE_BASE, keysSub<n> else Msg(@WINDOW , "Could not read from the Knowledge_Base table in the loop") return end if n = 1 then iContPos = iContPos + 1 content<iContPos> = '1-2:':RECORD<TYPE$> list2 = RECORD<TYPE$> /*We can now get all the TITLES in the table and add them to the CONTENT list of information*/ gosub getAllTitles end else locate RECORD<TYPE$> in list2 using @FM setting pos then **This TYPE is already there so don't add it again** end else iContPos = iContPos + 1 content<iContPos> = '1-2:':RECORD<TYPE$> list2 = list2:@FM:RECORD<TYPE$> /*We can now get all the TITLES in the table and add them to the CONTENT list of information*/ gosub getAllTitles end end next n return ************************************************************** getAllTitles: /* These parameters will be passed to Btree.Extract to get all the TITLES according to the TYPE of the current record. This search string has to be sure to only get the TITLES that are associated with it's corresponding TYPE and PRODUCT */ search_string = "TYPE":@VM:"=":Record<TYPE$>:@FM:"PRODUCT":@VM:"=":RECORD<PRODUCT$>:@FM table = "KNOWLEDGE_BASE" open "DICT.":table To @DICT else Msg(@WINDOW , "Could not open the DICTIONARY in the getAllTitles subroutine in the POPULATE click") return end keysSub2 = '' optionSub2 = '' flagSub2 = '' list3 = '' /* IF Btree.Extract is successful, the variable "KEYS" holds the list of keys, @VM delimited, for responses for the main topic */ Btree.Extract(search_string, table, @DICT, keysSub2, optionSub2, flagSub2) **Get the number of keys returned by Btree.Extract iKeyCountSub2 = count(keysSub2,@VM) + (len(keysSub2)>0) convert @VM to @FM in keysSub2 open 'KNOWLEDGE_BASE' to hKNOWLEDGE_BASE else Msg(@WINDOW , "Could not open the table KNOWLEDGE_BASE in the subroutine getAllTitles in the POPULATE click") return end /* If iKeyCountSub2 is empty then there are no matching criteria for the search so the loop will not be executed */ for t = 1 to iKeyCountSub2 read RECORD from hKNOWLEDGE_BASE, keysSub2<t> else call Msg(@WINDOW , 'Could not read from the Knowledge_Base table') return end iContPos = iContPos + 1 content<iContPos> = '3-3:':RECORD<TITLE$> next t return
Call this function from the CLICK event of the B_POPULATE button, as shown below. Substitute your account for EXAMPLES.
