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Differences, operation and parameters of the CollectObjects function of the Object Manager

Differences, operation and parameters of the CollectObjects functions of the Object Manager

General information

The CollectObjects functions collect all objects of a class in the database and return them to the
back to the calling party.

Due to the large number of objects, problems have arisen in the various use cases that
have made it necessary to implement several versions.

See also CX_DB_UTLILITY::FindAll

CollectObjects

Collects the objects of the required class with the ObjectStore construct os_dynamic_extent.
This is the most effective method, but there are the following special features:

  • the result collection is pointer-based, i.e. it cannot be used after the end of the transaction
  • Address space overflow is not handled

Syntax:
nClassID nMode GetManager(OBJECT) Call(CollectObjects) -> collFoundObjects

Parameters
Name Meaning

nClassID

A class ID according to the schema CX_CLASS_ID (for example, CX_STAFF_MEMBER)

nMode

The parameter mode controls whether the entire database or only the active segment of the class is searched. The values are shown in the following table.
0 search the whole database ... this variant must be used for
  • Segment splitting
  • Clustering if the searched objects are slave objects
1 The system only searches in the current object segment of the class

CollectObjects2

The objects are collected with a ClassiX®-own routine, whereby address space overflow is handled. Like CollectObjects(), the first parameter determines the class. The second parameter controls whether objects derived from this class are also collected.

The function CollectObjects2 starts and ends transactions independently. No transaction must be open before the call, otherwise the maximum release of address space after an overflow is not possible!

The result is a ("normal") reference-based collection, which can also be suspended across transaction boundaries.
The entire database is always searched.

Syntax:
nClassID bInheritance GetManager(OBJECT) Call(CollectObjects2) -> collFoundObjects

Parameters
Name Meaning

nClassID

A class ID according to the schema CX_CLASS_ID (for example, CX_STAFF_MEMBER)

bInheritance

The parameter mode controls whether the entire database or only the active segment of the class is searched. The values are shown in the following table.

FALSE

Only objects of the class specified with the parameter nClassID

TRUE

also include objects of derived classes

CollectObjects3

The objects are collected with a ClassiX®-own routine, whereby address space overflow is handled.

The function CollectObjects3 starts and ends transactions independently. No transaction must be open before the call, otherwise the maximum release of address space after an overflow is not possible!

The result is a ("normal") reference-based collection with a maximum of nMaxElements objects, which can also be resolved across transaction boundaries. Once this collection has been processed, the next nMaxElements objects can be given with a new call of CollectObjects3(). If the result collection is empty, the database search has been successfully completed.

The entire database is always searched.

Syntax:
nCmd nMaxElements nClassID bInheritance GetManager(OBJECT) Call(CollectObjects2) -> collFoundObjects

Parameters
Name Meaning

bInheritance

The parameter mode controls whether the entire database or only the active segment of the class is searched. The values are shown in the following table.
FALSE Only objects of the class specified with the parameter nClassID
TRUE also include objects of derived classes

nClassID

A class ID according to the schema CX_CLASS_ID (for example, CX_STAFF_MEMBER)

nMaxElements

An integer value that determines the maximum size of the result collection.

nCmd

Determines the mode in which CollectObjects3() should be executed on the next call.
The values are shown in the following table.
0 Continue normally and supply the next nMaxElements
1 search for new from the beginning
2 Recover: The last collection should be resent. This is useful if an error occurred during processing of the collection in the instant view code and was corrected.

Code examples

  Define (Beispiel_fuer_CollectObjects2)
    // hier wird der CollectObjects2 gestartet MIT Inheritance
    // das Ergebnis ist eine Collection mit allen gefundenen Objekten,
    // also auch den von CX_TELECOM abgeleiteten !!!
    CX_TELECOM TRUE GetManager(OBJECT) Call(CollectObject2)
    iterate 
    {
       // hier wird etwas mit den gesammelten Objekten getan.
       // z.B. ein Reorg, Retype, oder ähnliches
    }
  ;
      

  Define (Beispiel_fuer_CollectObjects3)
    Var(CO3_NORMAL, CO3_RESET, CO3_REPEAT, nMode)
        0 -> CO3_NORMAL
        1 -> CO3_RESET
        2 -> CO3_REPEAT

 

    // Modus für den ersten Aufruf muss CO3_RESET sein
    CO3_RESET -> nMode

    do {
      // hier wird der CollectObjects3 gestartet OHNE Inheritance
      // das Ergebnis ist eine Collection mit maximal 5000 Objekten           
      nMode 5000 CX_ATTRIBUTE_SET FALSE GetManager(OBJECT) Call(CollectObject3)
      
              // Modus für folgende Aufrufe auf CO3_NORMAL setzen
              CO3_NORMAL -> nMode

      // Test, ob das Durchsuchen beendet ist...
      Dup if Cardinality 0 = if 
        { Drop break } 

      // Bearbeiten der Ergebnis Collection
      iterate 
      {
        // hier wird etwas mit den gesammelten Objekten getan.
        // z.B. ein Reorg, Retype, oder ähnliches
      }
    } loop 
  ;