db4o Developer Community

consider the following case: i am storing items i1 and i2 storing a list of other items (i1 contains i11 and i12, i2 cotnains i21). i want to retrieve only those items (i1 or i2) that contain two other items (i11 and i12). the following code returns i1 if i query for items that contain i11 or i12 but not if i want to make sure that the returned ...

Hello! Can somebody tell me how SODA behaves for querying Lists? Assumed that Foo is a class which got a field (List _bars) which holds Bar-Objects and I want to get all Foos which got a special Bar. Does this Query Query q = _objectContainer.query();q.constrain(Foo.class);q.descend(''_bars'').constrain(special_bar); // special_bar is a ...

Hi,we are new users in db4o and have the following problem using a java class construct like:class Folder {    Stirng name;    List mails;}  class Mail {    String subject;}Now we have some folders (e.g. ''inbox'', ''sent'' ...) containing mails.We are trying to search for mails with a subject ...

I experience exactly the problem as described in Eric´s post from 2-04-2006... My query constrains by an interface (query.constrain(myInterface.class) - that part is working just fine giving all the objectsstored that implement that interface. But now the trouble begins:I add another constrain for a member of the classes that would be returned ...

So, here's the code: public static IEnumerable<Alias> GetFromParent(HasAliases parent) {         Query query = _db.Query();         query.Constrain(typeof(Alias));         ...

Hi, Sorry for late feedback - I have been busy with other development. Just wanted to summarize: - On the original question about OR union and custom evaluators - I solved my problem by running several queries and then using collections and operating on them to make the OR or AND. Maybe not as quick and politically correct, but it gets the job ...

  Db4o does not respond correctly to a query on an index field of type long. The query in this example restricts the result set to a range of values. query.execute() delivers an empty result set if the upper limit of the range is a value which does not exist in the database. I have not investigated wether this bug also appears if ...

The above way to set up your query is perfect. ....if you use the latest 5.7 build which is just about ready. See: http://developer.db4o.com/blogs/product_news/archive/2006/09/18/New-BTree-Field-Index-Processor.aspx   After you have had the chance to try out 5.7, please post back how the results changed. We would love to hear about it.