Friday, 17 June 2016

Putlistitems - successive occurrences

I've used putlistitems a lot, it's very useful.  Different switches all it to do different things, so for example, /occ will populate a variable with an associative list of field names and values, something like this...

  putlistitems/occ varMyList,"ENT"

"varMyList" will now be something like "FIELD1=VALUE1·;FIELD2=VALUE2·;etc".

This can further be modified by adding /modonly, which will only add field values to the list which have been modified since the record was retrieved, something like this...

  putlistitems/occ/modonly varMyList,"ENT"

However, the one I tend to use most is /id.  This will take the values of the specified field from multiple occurrences and put them into a list, something like this...

  varMyList = "FIELD1"
  putlistitems/id varMyList

"varMyList" will now be something like "VALUE1·;VALUE1·;etc", repeated for each occurrence.

This allows you to quickly grab the values of the field(s) you're interested in, without having to loop through the occurrences in order to build the list, which is much better for performance.

Or you can also use it to update the representations in a list, for example, backing up a load of field or register values...

  varMyList = "$1·;$2·;$3"
  putlistitems/id varMyList

"varMyList" will now be something like "$1=REG1·;$2=REG2·;$3=REG3".

All of this is well documented in the Uniface manuals, so you may well be asking me why I'm telling you this.  Fair question.

I never realised that the first use of /id, taking the values of the specified field from multiple occurrences, was actually successive occurrence.  This means that it will start on the current occurrence and loop through to the end, completing the hitlist if required.

The manuals make this clear, with the following note...
To ensure that the entire set of occurrences in the component is being addressed, make the first occurrence the current occurrence.

What this means is, use setocc first, like this..

  setocc "ENT",1
  varMyList = "FIELD1"
  putlistitems/id varMyList

I hope I've not been caught out by this in the past!

Summary: putlistitems/id will look at successive occurrences, so if you want the whole hitlist, remember to make sure the current occurrence is the first occurrence.