If you need to merge data in an ABL temp-table with XML data, you can control the way in which the AVM handles duplicate unique key conflicts with the read-mode parameter. In this example, a new temp-table is set up with definition from the Customer table and two new records. This set-up code is stored in an include file. Note that the first record uses a customer number that conflicts with one in the XML document. The second record has no conflict with the XML document, as shown:

/* pi-tfx-ttSetup-5.i */
/* Creates a new static temp-table and creates two new records for it. */
DEFINE TEMP-TABLE ttCustomer NO-UNDO
   /* Field and index definitions. */

CREATE ttCustomer.
ASSIGN 
  ttCustomer.Name     = "Extreme XML Sports"
  ttCustomer.CustNum  = 1
  ttCustomer.Balance  = 111.11
  ttCustomer.Country  = "USA"
  ttCustomer.Comments = "Enthusiastic new customer!".

CREATE ttCustomer.
ASSIGN 
  ttCustomer.Name     = "Low-Impact XML Sports"
  ttCustomer.CustNum  = 4
  ttCustomer.Balance  = 444.44
  ttCustomer.Country  = "USA"
  ttCustomer.Comments = "Mellow new customer.".

The following is an abbreviated copy of the ttCustomer.xml file:

<?xml version="1.0"?>
<ttCustomer xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <ttCustRow>
    <CustNum>1</CustNum>
    <Country>USA</Country>
    <Name>Lift Tours</Name>
    ...
   </ttCustRow>
  <ttCustRow>
    <CustNum>2</CustNum>
    <Country>Finland</Country>
    <Name>Urpon Frisbee</Name>
    ,,,
</ttCustRow>
  <ttCustRow>
    <CustNum>3</CustNum>
    <Country>USA</Country>
    <Name>Hoops </Name>
    ...
</ttCustRow>
</ttCustomer>

To illustrate the different results obtained with each read-mode option, there is a unique index defined for the CustNum field. There is a record in both the include file and the XML file that uses the same CustNum value (1). This is known as a duplicate unique key conflict. The different read modes respond to such a conflict in different ways.

The code sample below performs the same READ-XML( ) method call you saw in the last example. Replace the highlighted variable value in the code with each of the following four read mode tokens and compare the results:

  • EMPTY
  • APPEND
  • MERGE
  • REPLACE 
* pi-tfx-read-5.p */
/* Merges records in a temp-table with records from an XML file.*/
{pi-tfx-parameterVarDefs.i}
{pi-tfx-ttSetup-5.i}

DEFINE VARIABLE lReturn AS LOGICAL NO-UNDO.

ASSIGN
  cSourceType             = "FILE"
  cFile                   = "ttCustomer.xml" 
  cReadMode               = "EMPTY"
  cSchemaLocation         = ?
  lOverrideDefaultMapping = ?
  cFieldTypeMapping       = ?
  cVerifySchemaMode       = ?.

lReturn = TEMP-TABLE ttCustomer:READ-XML(cSourceType, cFile, cReadMode, 
  cSchemaLocation, lOverrideDefaultMapping, cFieldTypeMapping,
  cVerifySchemaMode).
IF lReturn THEN
FOR EACH ttCustomer:
  DISPLAY ttCustomer.CustNum ttCustomer.Name FORMAT "X(30)".
END.

Compare your results to those shown and explained in the following table.

Table 1. Read mode examples
Read mode List result Explanation
EMPTY

The method empties the existing data from the temp-table. It then reads the XML document and adds records to the temp-table. Since the temp-table is empty, there is no duplicate key conflict. The result is a temp-table with records exclusively from the XML document.
APPEND

The method reads the XML document and adds records to the temp-table. Due to the duplicate key conflict between the record in the temp-table and the record in the XML with a CustNum of 1, the method stops loading records and stops. Records added before a conflict is detected are retained. The AVM displays the error message shown.
MERGE

The method reads the XML document and adds records to the temp-table. Due to the duplicate key conflict between the record in the temp-table and the record in the XML with a CustNum of 1, the record from the XML is ignored. The result is all the existing records from the temp-table, plus all of the records from the XML except for the record with a CustNum of 1.
REPLACE

The method reads the XML document and adds records to the temp-table. Due to the duplicate key conflict between the record in the temp-table and the record in the XML with a CustNum of 1, the record from the XML replaces the record in the temp-table. The result is all the existing records from the temp-table except for the record with a CustNum of 1, plus all of the records from the XML.
Note: To see a version of the last example that uses a dynamic temp-table, look at the following sample files in the Doc_samples\xml directory: pi-tfx-ttSetup-6.i and pi-tfx-read-6.p