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 Grome808-737-6499WebDNA Solutionsmailto:ken@webdna.nethttp://www.webdna.net Associated Messages, from the most recent to the oldest:

Re: Date or time comparisons have bugs ... (Kenneth Grome 1998)
Re: Date or time comparisons have bugs ... (PCS Technical Support 1998)
Re: Date or time comparisons have bugs ... (Kenneth Grome 1998)
Re: Date or time comparisons have bugs ... (Kenneth Grome 1998)
Re: Date or time comparisons have bugs ... (PCS Technical Support 1998)
Re: Date or time comparisons have bugs ... (Dave MacLeay 1998)
Re: Date or time comparisons have bugs ... (Bob Minor 1998)
Date or time comparisons have bugs ... (Kenneth Grome 1998)

>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 Grome808-737-6499WebDNA Solutionsmailto:ken@webdna.nethttp://www.webdna.net Kenneth Grome

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Re: Date or time comparisons have bugs ...

1998

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