[odb-users] Query std::vector or object relationships

Jan Küntzer kuentzer at googlemail.com
Mon Jul 4 12:35:58 EDT 2011

Hi Boris

Thanks for the fast reply

You are right, what i would like to have in this example is the contains function. 

Another nice thing would be: 
For a vector of pointers, e.g. vector<Xref*> xrefs and Xref with string attribut db, it would be nice to have a chance for checking if one of the xrefs has the stated attribute. Something like

odb::query<UtitlityClass>::xrefs::db = "some_string"



Am 04.07.2011 um 18:09 schrieb Boris Kolpackov <boris at codesynthesis.com>:

> Hi Jan,
> Jan Kuentzer <kuentzer at googlemail.com> writes:
>> But the class UtilityClass has a std::vector<std::string> attribute called
>> "comment" and for this the following gives the mentioned compile error:
>> odb::query<UtitliyClass> q (odb::query<UtitlityClass>::comment ==
>> "some_string");
> There is currently no support for using container members as predicates 
> in the C++-integrated queries. As a workaround for the meantime you can
> use native queries (which are essentially the SQL WHERE text).
> Also, for when we get to supporting this, it would be helpful to know what
> kind operations you expect to be able to perform on container. The one
> that you use above doesn't make much sense since a vector of strings
> cannot be meaningfully compared to a string. Maybe something like this:
> odb::query<UtitlityClass>::comment.contains ("some_string")
> Or
> odb::query<UtitlityClass>::comment[0] == "some_string"
> ?
> Boris

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