Re: Date or time comparisons have bugs ...
This WebDNA talk-list message is from 1998
It keeps the original formatting.
numero = 16992
interpreted = N
texte = >The problem is not in your [Search] parameters, but in the fact that you >are doing a [Delete] within a [FoundItems] loop. > >I'm sure that Grant can explain this better than I can, but when you do a >search, WebCat creates its own internal list of matching items and >remembers them by their positions in the database.Okay, then in reality, WebCatalog is using the [index] position of the founditems context -- not the cartID -- to decide which records it will delete ...>[FoundItems] then loops >through each of those records, first performing the desired operations on >the first found record in the db, then on the second, etc. Having a >[Delete] inside [FoundItems] messes this up, because it changes the >position of records in your database. > >For example, say the [Search] finds records 1,2,and 6. On the first >[FoundItems] loop, record 1 is deleted. With record 1 gone, the original >record 2 becomes record 1, and every other record moves up a position >(2->1, 3->2, 4->3, etc.). So when [FoundItems] comes through looking for >record 2, it is really finding the original record 3, which may or may not >have met the search criteria. The original record 2 gets skipped altogether. Thanks Dave,Your explanation is very clear. All you're saying here is that the delete is *not* deleting records based on the cartID, but in the first step, delete is simply *flagging* the records to be deleted -- and WebCat is using the [index] values in order to identify which records are to be deleted in the *next* step of the process.Then in the next step, WebCatalog tries to identify the records to be deleted based on their indexed position. But unfortunately, each time a record is deleted, the indexed position of all the remaining records changes -- and that's what's causing my results to NOT be as I expected them.Thanks, now I understand how this works.I think this is an extremely critical piece of information!If I may make a simple suggestion to PCS so that others will not fall into the same trap as I did, I think it would be a very good thing to place a simple warning in the HTML docs, perhaps something in big bold red letters like this: WARNING!Do NOT place a delete context inside a founditems context. You will NOT get the results you expect! There are complicated technical reasons for this, so we ask you to please remember a simple rule (which will keep you out of trouble when deleting records):NEVER put a [delete] context inside a [founditems] context. ALWAYS use a [delete] context by itself when deleting records.Sincerely, Ken Grome 808-737-6499 WebDNA Solutions mailto:ken@webdna.net http://www.webdna.net
Associated Messages, from the most recent to the oldest:
>The problem is not in your
[search] parameters, but in the fact that you >are doing a
[delete] within a
[founditems] loop. > >I'm sure that Grant can explain this better than I can, but when you do a >search, WebCat creates its own internal list of matching items and >remembers them by their positions in the database.Okay, then in reality, WebCatalog is using the [index] position of the founditems context -- not the cartID -- to decide which records it will delete ...>
[founditems] then loops >through each of those records, first performing the desired operations on >the first found record in the db, then on the second, etc. Having a >
[delete] inside
[founditems] messes this up, because it changes the >position of records in your database. > >For example, say the
[search] finds records 1,2,and 6. On the first >
[founditems] loop, record 1 is deleted. With record 1 gone, the original >record 2 becomes record 1, and every other record moves up a position >(2->1, 3->2, 4->3, etc.). So when
[founditems] comes through looking for >record 2, it is really finding the original record 3, which may or may not >have met the search criteria. The original record 2 gets skipped altogether. Thanks Dave,Your explanation is very clear. All you're saying here is that the delete is *not* deleting records based on the cartID, but in the first step, delete is simply *flagging* the records to be deleted -- and WebCat is using the [index] values in order to identify which records are to be deleted in the *next* step of the process.Then in the next step, WebCatalog tries to identify the records to be deleted based on their indexed position. But unfortunately, each time a record is deleted, the indexed position of all the remaining records changes -- and that's what's causing my results to NOT be as I expected them.Thanks, now I understand how this works.I think this is an extremely critical piece of information!If I may make a simple suggestion to PCS so that others will not fall into the same trap as I did, I think it would be a very good thing to place a simple warning in the HTML docs, perhaps something in big bold red letters like this: WARNING!Do NOT place a delete context inside a founditems context. You will NOT get the results you expect! There are complicated technical reasons for this, so we ask you to please remember a simple rule (which will keep you out of trouble when deleting records):NEVER put a
[delete] context inside a
[founditems] context. ALWAYS use a
[delete] context by itself when deleting records.Sincerely, Ken Grome 808-737-6499 WebDNA Solutions mailto:ken@webdna.net http://www.webdna.net
Kenneth Grome
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