Hi Mike, I've read the example of dogpile caching. For my case dogpile.cache seems to be a overkill, could you please provide a thinner example of using Query.merge_result without involving another library? Thanks.
On Thu, Jul 13, 2017 at 8:07 PM, Jinghui Niu <niujing...@gmail.com> wrote: > Thanks Mike. Just to clarify, so instead of caching a Query object, I > should cache all those queried instance in my `self.search_result_cache`, > is this the idea? Is there a way to just relay Query object from one method > to another? Which seems a little simpler to me. > > On Thu, Jul 13, 2017 at 7:20 PM, Mike Bayer <mike...@zzzcomputing.com> > wrote: > >> you need to use Session.merge and/or Query.merge_result so that a >> *copy* of the detached object is placed into the Session. In >> particular, Query.merge_result was created for the use case of caching >> result sets. >> >> http://docs.sqlalchemy.org/en/latest/orm/query.html?highligh >> t=merge_result#sqlalchemy.orm.query.Query.merge_result >> >> >> this links to the dogpile cache example at >> http://docs.sqlalchemy.org/en/latest/orm/examples.html#modul >> e-examples.dogpile_caching >> illustrates a method that I've used in production successfully. >> >> >> >> >> >> On Thu, Jul 13, 2017 at 7:38 PM, Jinghui Niu <niujing...@gmail.com> >> wrote: >> > I have a web application served by cherrypy (, which is multi-threaded. >> ) >> > >> > I'm trying to cache a set of rows queried from database using >> > `self.search_result_cache` variable on the GUI_Server object. On my >> > front-end, the web first request `list_entries` to prepare the rows and >> > stores them on `self.search_result_cache`. After that, on user's mouse >> click >> > the front-end initiats another request calling `Record_entries_count`, >> which >> > is expected to revive the Query from `self.search_result_cache` and >> continue >> > on to do some data refining, e.g. summing up the count in this case. >> > >> > class GUI_Server: >> > >> > >> > def __init__(self): >> > self.search_result_cache = None >> > >> > >> > @cherrypy.expose >> > def list_entries(self, **criteriaDICT): >> > # always store the result to self cache >> > >> > ... >> > >> > >> > db = cherrypy.request.db_session >> > >> > >> > filter_func = getattr(self, 'filterCriteria_' + >> > classmodel_obj.__name__) >> > queryOBJ = filter_func(criteriaDICT, queryOBJ) >> > self.search_result_cache = queryOBJ >> > db.expunge_all() >> > >> > .... >> > >> > def Record_entries_count(self): >> > db = cherrypy.request.db_session >> > query_subset = self.search_result_cache >> > result = query_subset.count() >> > return result >> > >> > >> > But this doesn't work. It always give me an error: >> > >> > sqlite3.ProgrammingError: SQLite objects created in a thread can only be >> > used in that same thread.The object was created in thread id >> 139937752020736 >> > and this is thread id 139938238535424 >> > >> > >> > I am already using `scoped_session` for each request session. I don't >> > understand why I got this error. >> > >> > >> > What is the best pratice to cache queried result across different >> request >> > sessions like this? Thanks a lot. >> > >> > -- >> > SQLAlchemy - >> > The Python SQL Toolkit and Object Relational Mapper >> > >> > http://www.sqlalchemy.org/ >> > >> > To post example code, please provide an MCVE: Minimal, Complete, and >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full >> > description. >> > --- >> > You received this message because you are subscribed to the Google >> Groups >> > "sqlalchemy" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an >> > email to sqlalchemy+unsubscr...@googlegroups.com. >> > To post to this group, send email to sqlalchemy@googlegroups.com. >> > Visit this group at https://groups.google.com/group/sqlalchemy. >> > For more options, visit https://groups.google.com/d/optout. >> >> -- >> SQLAlchemy - >> The Python SQL Toolkit and Object Relational Mapper >> >> http://www.sqlalchemy.org/ >> >> To post example code, please provide an MCVE: Minimal, Complete, and >> Verifiable Example. 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