[google-appengine] Re: Complex tagging of items
Here's where old good relational databases theory comes in. How will I do it: Create a model ``Tags'': class Tags(db.Model): tag_name = db.StringProperty() Create a model ``Items'': class Items(db.Model): item_name = db.StringProperty() And create a model ``ItemTags'' class ItemTags(db.model): tag = db.ReferenceProperty(Tags) item = db.ReferenceProperty(Items) So when you need to get items for some tags you first query the ``ItemTags'' for items with concrete tag(s) thgan by key you get Items. Cheers, Serhiy On Jan 24, 3:17 am, George Sudarkoff sudark...@gmail.com wrote: I have a bit of a problem coming up with an efficient data model/algo for a project I am working on: I have a few hundred items, each tagged with zero or more tags. I need to be able to fetch items that, for example, are tagged with tag1 AND (tag2 OR tag3) AND NOT tag4. Any help would be greatly appreciated! --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: Complex tagging of items
On Jan 25, 11:17 pm, ryan ryanb+appeng...@google.com wrote: On Jan 25, 11:43 am, Anthony acorc...@gmail.com wrote: If you store the tags as a StringList wouldn't this query work.. WHERE tags = tag1 AND tags IN [tag2,tag3] AND tags != tag4 From the docs it says the IN != do run multiple queries behind the scenes so not sure if it will be as quick as running it in memory for a few hundred items, but if you need more than a few hundred items you are not going to be able to do it in memory before it starts timing out. good call, anthony! that query does indeed do what george wants, and you're right about how != and IN work behind the scenes. the problem with that query, unfortunately, is that it needs this index: - kind: Foo properties: - name: tags - name: tags - name: tags ...which is almost certain to explode on entities with any more than a handful of tags: http://code.google.com/appengine/docs/python/datastore/queriesandinde... Very cool! On average I won't have more than 2-3 tags per item, so I really think this solution might work! I'll try it and report back the results. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: Complex tagging of items
This is what I have right now for simple 'tag1 OR tag2' cases. But how do you efficiently retrieve items for 'tag1 AND (tag2 OR tag3) AND NOT tag4' with this model? On Jan 27, 12:59 am, Seronja ser...@oplakanets.com wrote: Here's where old good relational databases theory comes in. How will I do it: Create a model ``Tags'': class Tags(db.Model): tag_name = db.StringProperty() Create a model ``Items'': class Items(db.Model): item_name = db.StringProperty() And create a model ``ItemTags'' class ItemTags(db.model): tag = db.ReferenceProperty(Tags) item = db.ReferenceProperty(Items) So when you need to get items for some tags you first query the ``ItemTags'' for items with concrete tag(s) thgan by key you get Items. Cheers, Serhiy On Jan 24, 3:17 am, George Sudarkoff sudark...@gmail.com wrote: I have a bit of a problem coming up with an efficient data model/algo for a project I am working on: I have a few hundred items, each tagged with zero or more tags. I need to be able to fetch items that, for example, are tagged with tag1 AND (tag2 OR tag3) AND NOT tag4. Any help would be greatly appreciated! --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: Complex tagging of items
taggable-mixin can help you with at least part of your problem. http://code.google.com/p/taggable-mixin/ The kind of complex querying that you want to do can not be done with the datastore's native querying capabilities; you'll have to get results set and filter them in-memory. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: Complex tagging of items
If you store the tags as a StringList wouldn't this query work.. WHERE tags = tag1 AND tags IN [tag2,tag3] AND tags != tag4 From the docs it says the IN != do run multiple queries behind the scenes so not sure if it will be as quick as running it in memory for a few hundred items, but if you need more than a few hundred items you are not going to be able to do it in memory before it starts timing out. On Jan 24, 1:17 am, George Sudarkoff sudark...@gmail.com wrote: I have a bit of a problem coming up with an efficient data model/algo for a project I am working on: I have a few hundred items, each tagged with zero or more tags. I need to be able to fetch items that, for example, are tagged with tag1 AND (tag2 OR tag3) AND NOT tag4. Any help would be greatly appreciated! --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: Complex tagging of items
Since you only have a few hundred items, the easiest approach may be to filter the results in memory after performing a preliminary datastore query. I would store the tag names in a StringListProperty () on your model. Hope this helps, Chris On Jan 23, 5:17 pm, George Sudarkoff sudark...@gmail.com wrote: I have a bit of a problem coming up with an efficient data model/algo for a project I am working on: I have a few hundred items, each tagged with zero or more tags. I need to be able to fetch items that, for example, are tagged with tag1 AND (tag2 OR tag3) AND NOT tag4. Any help would be greatly appreciated! --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
