I did similar work in https://github.com/django/django/pull/4801. I aimed for 1.9, but had to defer the work due to problems with .exclude() filtering.
The problem is that if you query with .exclude(LessThan(F('friends__age'), 30)), you'll get different results than with .exclude(friends__age__lt=30). The latter does a subquery while the expression version isn't capable of that. Unfortunately, fixing this is a bit nasty. I don't see any other way than some solution like https://github.com/django/django/pull/4385 - that is we prewalk the expression tree and decide which parts need to be pushed in to a subquery. This should work really nice with expressions, too. I haven't taken a closer look on your approach, so I can't say which one we should use as basis for future work once we have solved the subquery problem. - Anssi On Mon, Oct 19, 2015 at 2:09 PM, Josh Smeaton <josh.smea...@gmail.com> wrote: > I think you forgot the PR link Alexey. I'd like to have a look at the > changes you've made. I'm not sure about the extensions to F() just yet, I'm > hoping they aren't actually needed for your patch to work, but will need to > review to be sure. > > Cheers > > > On Monday, 19 October 2015 21:49:37 UTC+11, Alexey Zankevich wrote: >> >> Hi all, >> >> Here is a raw pull request, allowing lookup instances passing to filter >> method >> There are two new test cases working: >> >> 1. Passing lookup with F object: >> Article.objects.filter(GreaterThan(F('id'), Value(5))) >> 2. And passing lookup with transforms: >> Article.objects.filter(Contains(Upper(Lower(Upper(F('headline')))), 'ARTICLE >> 5')) >> >> All the existing tests are passing successfully, by the way (at least for >> SQLite backend). >> >> Several comments: >> >> F expressions became real expressions (Expression subclass). >> Expression got a new method - get_source_f_object, which walks through >> children classes and find if it has F object passed. In that case >> output_field-related code should be postponed, until compiler resolves it >> (which cannot be done during lookup init time). >> some code related to query.build_filter method (responsible to >> lookups/transform parsing, and calculating joins), extracted into separate >> helper classes - QueryKeywordLookupHelper and QueryObjectLookupHelper. They >> have common code base, but some of methods work in a different way. >> >> Except review, it would be really great if someone help with writing test >> cases (and I'll get them working in case of any issues). Also, there is a >> workaround field=None -> isnull=True for oracle database, can anybody check >> if it is working correctly? >> >> Regards, >> Alexey >> >> >> On Thursday, October 1, 2015 at 11:38:39 AM UTC+3, Anssi Kääriäinen wrote: >>> >>> Lets concentrate on making expressions in filter calls and lookups as >>> expressions reality. When we have done that we can try out different >>> syntax approaches in 3rd party apps. Finally, after we have field >>> tested the approaches, we can merge something in to Django. >>> >>> - Anssi >>> >>> On Thu, Oct 1, 2015 at 10:49 AM, Alexey Zankevich >>> <alex.za...@gmail.com> wrote: >>> >> I think the `F('name').decode('utf-8')` syntax is a good candidate for >>> >> core. >>> > >>> > When Django supports expression lookups, it will be possible to build >>> > syntax >>> > sugar third-party library on top of it. >>> > For example, it will be possible to implement dotted syntax for F >>> > objects: >>> > >>> > UserModel.objects.filter(Decode(F.user.name, 'utf-8') == u'Бармаглот') >>> > >>> > alternatively it can be even combined with your syntax >>> > >>> > UserModel.objects.filter(F.user.name.decode('utf-8') == u'Бармаглот') >>> > >>> > However, the second solution will be more complicated from technical >>> > point >>> > of view (as will require lazy object, collecting all the func or >>> > transform >>> > calls), also it will require to be really careful with transform names >>> > not >>> > to conflict with possible field names. >>> > For example, it's hardly possible to have "decode" field in the model, >>> > but >>> > easily - "date". >>> > >>> > >>> > On Thursday, October 1, 2015 at 10:18:40 AM UTC+3, Loïc Bistuer wrote: >>> >> >>> >> > On Oct 1, 2015, at 13:38, Anssi Kääriäinen <akaa...@gmail.com> >>> >> > wrote: >>> >> > >>> >> > +1 to not requiring all transforms to handle __underscore__ syntax. >>> >> >>> >> +1 >>> >> >>> >> > I think what we want to do is allow users choose which syntax they >>> >> > prefer. The idea is that Django will support both >>> >> > JSONExtract('data', >>> >> > path=['owner', 'other_pets', 0, 'name']) and >>> >> > data__owner__other_pets__0__name out of the box. >>> >> > >>> >> > We will also make it possible to support callable transforms. For >>> >> > example: >>> >> > filter(Exact(Decode(F('name'), 'utf-8'), Value(u'Бармаглот'))) >>> >> > is equivalent to >>> >> > filter(F('name').decode('utf-8') == Value(u'Бармаглот')) >>> >> > >>> >> > The callable transforms syntax will not be a part of Django, but it >>> >> > will be possible to create an extension for this (it is actually >>> >> > surprisingly easy to do once we have support for expressions in >>> >> > filter). >>> >> >>> >> I'm pretty convinced we need a better API / sugar as part of core in >>> >> the >>> >> long run. >>> >> >>> >> The `filter(Exact(Decode(F('name'), 'utf-8'), Value(u'Бармаглот')))` >>> >> syntax is not pythonic and very hard to decipher, and we've reached >>> >> the >>> >> limits of our historical double underscore syntax (doesn't support >>> >> multiple >>> >> arguments, limited to ascii, etc.). >>> >> >>> >> I think the `F('name').decode('utf-8')` syntax is a good candidate for >>> >> core: >>> >> >>> >> - It's a small extension to the existing F objects, so it's easy to >>> >> grasp >>> >> for existing Django users. >>> >> - It's just a thin sugar on top of the canonical API. >>> >> - All the required machinery being already in place (lookup & >>> >> transform >>> >> registration) the change to Django is minimal. >>> >> >>> >> > - Anssi >>> >> > >>> >> > On Thu, Oct 1, 2015 at 4:00 AM, Josh Smeaton <josh.s...@gmail.com> >>> >> > wrote: >>> >> >> No, not all Lookups or Transforms are required to handle >>> >> >> __underscore__ >>> >> >> syntax. The entire point of supporting object based lookups is to >>> >> >> handle >>> >> >> cases that get more complex than a single argument transform or a >>> >> >> left >>> >> >> and >>> >> >> right hand side lookup. >>> >> >> >>> >> >> In particular, I think your Decode(utf8) example is a good one. It >>> >> >> shows >>> >> >> that you could maybe shoehorn multiple arg transforms into the >>> >> >> __underscore__ api, but it wouldn't be entirely obvious how to do >>> >> >> so. >>> >> >> You'd >>> >> >> probably need to register partial transformations for each encoding >>> >> >> you >>> >> >> wanted to support. The contrib.postgres module has (from memory) >>> >> >> KeyTransform classes that do a similar thing. >>> >> >> >>> >> >> Cheers >>> >> >> >>> >> >> >>> >> >> On Thursday, 1 October 2015 02:13:41 UTC+10, Alexey Zankevich >>> >> >> wrote: >>> >> >>> >>> >> >>> I'll try to turn lookups into expression (will use master branch). >>> >> >>> I also have a question. Meanwhile the old query syntax with >>> >> >>> underscores is >>> >> >>> pretty good for simple queries (like >>> >> >>> Model.objects.filter(name='Bob'), >>> >> >>> it >>> >> >>> gets really ugly for parametrized calls, a new JSONField is a good >>> >> >>> example >>> >> >>> of that: >>> >> >>> >>> >> >>>>>> Dog.objects.filter(data__owner__other_pets__0__name='Fishy') >>> >> >>> [<Dog: Rufus>] >>> >> >>> >>> >> >>> It will get even more messy if we want to pass a string as a >>> >> >>> second >>> >> >>> param >>> >> >>> of the func. >>> >> >>> >>> >> >>> ex.: >>> >> >>> >>> >> >>> 1. filter(Decode(F('name'), 'utf-8'), Value(u'Бармаглот')) # <- >>> >> >>> neat >>> >> >>> 2. filter(name__decode__utf8=u'Бармаглот') # <- ?? ambiguous and >>> >> >>> not >>> >> >>> nice >>> >> >>> at all >>> >> >>> >>> >> >>> So question - is it implied all the funcs, transforms and lookups >>> >> >>> to >>> >> >>> have >>> >> >>> underscore-based equivalent? It can affect the final >>> >> >>> implementation >>> >> >>> pretty >>> >> >>> much. In my opinion underscore-based equivalent should not be >>> >> >>> really >>> >> >>> required for funcs (the problem doesn't seem to affect transforms >>> >> >>> as >>> >> >>> they >>> >> >>> will not accept multiple params according to another thread). >>> >> >>> >>> >> >>> Thanks, >>> >> >>> Alexey >>> >> >>> >>> >> >>> >>> >> >>> On Wednesday, September 30, 2015 at 9:19:51 AM UTC+3, Anssi >>> >> >>> Kääriäinen >>> >> >>> wrote: >>> >> >>>> >>> >> >>>> I don't think we need split-to-subq support for Lookups before we >>> >> >>>> make >>> >> >>>> them expressions. Lookups as expressions are usable outside >>> >> >>>> .filter(), >>> >> >>>> and we need the split-to-subq support only in >>> >> >>>> .filter(expression). >>> >> >>>> >>> >> >>>> - Anssi >>> >> >>>> >>> >> >>>> On Wed, Sep 30, 2015 at 8:46 AM, Josh Smeaton >>> >> >>>> <josh.s...@gmail.com> >>> >> >>>> wrote: >>> >> >>>>> I'm mixing my versions, sorry to those following along. 1.9 has >>> >> >>>>> just >>> >> >>>>> reached >>> >> >>>>> alpha. Lookups as Expressions should be doable for 1.10 which >>> >> >>>>> master >>> >> >>>>> is >>> >> >>>>> currently tracking. >>> >> >>>>> >>> >> >>>>> Cheers >>> >> >>>>> >>> >> >>>>> >>> >> >>>>> On Wednesday, 30 September 2015 15:31:24 UTC+10, Josh Smeaton >>> >> >>>>> wrote: >>> >> >>>>>> >>> >> >>>>>> The alpha for 1.10 has already been cut, and I'm not sure that >>> >> >>>>>> the >>> >> >>>>>> kinds >>> >> >>>>>> of changes needed here are appropriate to add now that the >>> >> >>>>>> alpha is >>> >> >>>>>> out. One >>> >> >>>>>> could *maybe* make the argument that changing Lookup to an >>> >> >>>>>> Expression >>> >> >>>>>> now >>> >> >>>>>> rather than later is the right move considering Transforms just >>> >> >>>>>> underwent >>> >> >>>>>> the same change for 1.10. Personally though, I don't think I >>> >> >>>>>> have >>> >> >>>>>> the >>> >> >>>>>> time >>> >> >>>>>> right now to do this change. I would support you if you were >>> >> >>>>>> able, >>> >> >>>>>> but >>> >> >>>>>> we'd >>> >> >>>>>> still be at the mercy of the technical board (I assume) for >>> >> >>>>>> getting >>> >> >>>>>> this >>> >> >>>>>> change in for 1.10. >>> >> >>>>>> >>> >> >>>>>> Do you think Lookup as Expressions requires the >>> >> >>>>>> subquery/exclude >>> >> >>>>>> fix >>> >> >>>>>> you >>> >> >>>>>> mention above? I would think not -- not until we were ready to >>> >> >>>>>> document and >>> >> >>>>>> support .filter(Lookup(F(), Value()). If it wasn't a >>> >> >>>>>> requirement, >>> >> >>>>>> it'd >>> >> >>>>>> make >>> >> >>>>>> the Lookup->Expression work much easier. It wouldn't even need >>> >> >>>>>> to >>> >> >>>>>> be >>> >> >>>>>> documented (other than the release notes), as it'd just be an >>> >> >>>>>> implementation >>> >> >>>>>> change. >>> >> >>>>>> >>> >> >>>>>> Cheers, >>> >> >>>>>> >>> >> >>>>>> On Wednesday, 30 September 2015 14:33:14 UTC+10, Anssi >>> >> >>>>>> Kääriäinen >>> >> >>>>>> wrote: >>> >> >>>>>>> >>> >> >>>>>>> On the core ORM side we need to make >>> >> >>>>>>> .exclude(LessThan(F('friends__age'), 30)) do a subquery. This >>> >> >>>>>>> way >>> >> >>>>>>> .exclude(friends__age__lt=30) does the same thing as the >>> >> >>>>>>> expression >>> >> >>>>>>> version. This isn't that easy to do. If we just use >>> >> >>>>>>> resolve_expression, then the friends relation will generate a >>> >> >>>>>>> join, >>> >> >>>>>>> and then as second step do a negated filter on the joined >>> >> >>>>>>> value. >>> >> >>>>>>> Instead we want to detect that the LessThan expression needs >>> >> >>>>>>> to be >>> >> >>>>>>> pushed in to a subquery. >>> >> >>>>>>> >>> >> >>>>>>> So, we need to solve: >>> >> >>>>>>> >>> >> >>>>>>> A) A way to ask an expression if it is referencing a multijoin >>> >> >>>>>>> (possible approach is to just have a method >>> >> >>>>>>> "refs_multi_valued_relation(query)") >>> >> >>>>>>> B) When the ORM sees an expression that is reffing a multijoin >>> >> >>>>>>> in >>> >> >>>>>>> an >>> >> >>>>>>> exclude filter, then we need to push the expression in to a >>> >> >>>>>>> subquery. >>> >> >>>>>>> >>> >> >>>>>>> A) requires some new work. This shouldn't be that hard to >>> >> >>>>>>> implement, >>> >> >>>>>>> we just recursively ask subexpressions if they reference a >>> >> >>>>>>> multijoin. >>> >> >>>>>>> >>> >> >>>>>>> Something like https://github.com/django/django/pull/4385 will >>> >> >>>>>>> make >>> >> >>>>>>> B) >>> >> >>>>>>> much easier to implement. >>> >> >>>>>>> >>> >> >>>>>>> I've been working on making Q-objects responsible for >>> >> >>>>>>> resolving >>> >> >>>>>>> themselves. See https://github.com/django/django/pull/4801. >>> >> >>>>>>> This >>> >> >>>>>>> should solve 3). >>> >> >>>>>>> >>> >> >>>>>>> We don't seem to be missing any major parts. I (or some >>> >> >>>>>>> volunteer) >>> >> >>>>>>> just need to finish the PRs, and then we should be really >>> >> >>>>>>> close to >>> >> >>>>>>> full support for expressions in filter. >>> >> >>>>>>> >>> >> >>>>>>> Josh: do you think we could get Lookup as expressions in to >>> >> >>>>>>> 1.10 >>> >> >>>>>>> instead of 1.11? >>> >> >>>>>>> >>> >> >>>>>>> - Anssi >>> >> >>>>>>> >>> >> >>>>>>> On Wed, Sep 30, 2015 at 3:46 AM, Josh Smeaton >>> >> >>>>>>> <josh.s...@gmail.com> >>> >> >>>>>>> wrote: >>> >> >>>>>>>> 1. Lookups should become Expressions, just as Transforms have >>> >> >>>>>>>> become >>> >> >>>>>>>> Expressions. This will let us process Lookup arguments as >>> >> >>>>>>>> Expressions >>> >> >>>>>>>> all >>> >> >>>>>>>> the way the way through. I think this should be a major goal >>> >> >>>>>>>> for >>> >> >>>>>>>> version >>> >> >>>>>>>> 1.11. >>> >> >>>>>>>> >>> >> >>>>>>>> 2. Chaining transforms is now possible since they are just >>> >> >>>>>>>> Func >>> >> >>>>>>>> expressions. >>> >> >>>>>>>> Func(Func(Func('field_name'))) is no issue. >>> >> >>>>>>>> >>> >> >>>>>>>> 3. Sounds like an OK idea, but I haven't looked into the >>> >> >>>>>>>> details >>> >> >>>>>>>> enough >>> >> >>>>>>>> to >>> >> >>>>>>>> really comment. I do think we should create the correct form >>> >> >>>>>>>> as >>> >> >>>>>>>> early >>> >> >>>>>>>> as >>> >> >>>>>>>> possible (parsing into a chain of Lookup/Transform >>> >> >>>>>>>> expressions) >>> >> >>>>>>>> so >>> >> >>>>>>>> we >>> >> >>>>>>>> don't >>> >> >>>>>>>> have to do parsing in multiple places. The entry points to >>> >> >>>>>>>> .filter() >>> >> >>>>>>>> and >>> >> >>>>>>>> .exclude(), or their direct counterparts in sql.query sound >>> >> >>>>>>>> ideal. >>> >> >>>>>>>> Anssi has >>> >> >>>>>>>> mentioned elsewhere that WhereNode's should only contain >>> >> >>>>>>>> fully >>> >> >>>>>>>> resolved >>> >> >>>>>>>> expressions, so resolving will need to be done directly after >>> >> >>>>>>>> parsing >>> >> >>>>>>>> (or >>> >> >>>>>>>> during). >>> >> >>>>>>>> >>> >> >>>>>>>> Part 1 above can be started now if you have the time or >>> >> >>>>>>>> interest. >>> >> >>>>>>>> We >>> >> >>>>>>>> can >>> >> >>>>>>>> nail down the particulars of part 3 while we're solving part >>> >> >>>>>>>> 1. >>> >> >>>>>>>> Part 1 >>> >> >>>>>>>> may >>> >> >>>>>>>> drive some of part 3. >>> >> >>>>>>>> >>> >> >>>>>>>> Cheers >>> >> >>>>>>>> >>> >> >>>>>>>> >>> >> >>>>>>>> On Wednesday, 30 September 2015 04:49:54 UTC+10, Alexey >>> >> >>>>>>>> Zankevich >>> >> >>>>>>>> wrote: >>> >> >>>>>>>>> >>> >> >>>>>>>>> Here is a list of issues to solve to support explicit >>> >> >>>>>>>>> transforms >>> >> >>>>>>>>> and >>> >> >>>>>>>>> lookups by filter (and exclude) methods. >>> >> >>>>>>>>> >>> >> >>>>>>>>> 1. Make Lookup.__init__ signature to support initialization >>> >> >>>>>>>>> with >>> >> >>>>>>>>> F >>> >> >>>>>>>>> objects >>> >> >>>>>>>>> or string path (e.g. GreaterThan(F('user__id'), 10) or >>> >> >>>>>>>>> GreaterThan('user__id', 10)), not sure it's possible to use >>> >> >>>>>>>>> simultaneously >>> >> >>>>>>>>> with the current approach with lhs, rhs initialization (even >>> >> >>>>>>>>> with >>> >> >>>>>>>>> moving it >>> >> >>>>>>>>> to a separate class method, e.g Lookup.build(lhs, rhs)), so >>> >> >>>>>>>>> I >>> >> >>>>>>>>> assume >>> >> >>>>>>>>> creating so-called util classes which will delegate >>> >> >>>>>>>>> SQL-related >>> >> >>>>>>>>> functionality to existing Lookup classes. >>> >> >>>>>>>>> >>> >> >>>>>>>>> 2. Chain transforms by passing them as argument: >>> >> >>>>>>>>> >>> >> >>>>>>>>> Lower(Unaccent(F('user__name))) >>> >> >>>>>>>>> >>> >> >>>>>>>>> 3. Decide if Q objects shall support explicit >>> >> >>>>>>>>> lookups/transforms >>> >> >>>>>>>>> as >>> >> >>>>>>>>> argument as well - it's a kind of logical step, as without Q >>> >> >>>>>>>>> objects >>> >> >>>>>>>>> it will >>> >> >>>>>>>>> not be possible to perform complicated conditions (AND, OR, >>> >> >>>>>>>>> NOT). >>> >> >>>>>>>>> In that case lookup/transform parsing should be moved from >>> >> >>>>>>>>> QuerySet >>> >> >>>>>>>>> object >>> >> >>>>>>>>> to Q object - filter will take already parsed lookup tree. >>> >> >>>>>>>>> Example: >>> >> >>>>>>>>> >>> >> >>>>>>>>> Q(user__name__lower__unaccent__icontains='Bob') will >>> >> >>>>>>>>> internally >>> >> >>>>>>>>> parse >>> >> >>>>>>>>> it >>> >> >>>>>>>>> and build next structure: >>> >> >>>>>>>>> >>> >> >>>>>>>>> Q(Icontains(Lower(Unaccent(F('user__name')))), 'Bob') >>> >> >>>>>>>>> >>> >> >>>>>>>>> >>> >> >>>>>>>>> On Sunday, August 16, 2015 at 4:18:26 PM UTC+3, Alexey >>> >> >>>>>>>>> Zankevich >>> >> >>>>>>>>> wrote: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Hi all, >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> This topic is related to the current ORM query syntax with >>> >> >>>>>>>>>> underscores. >>> >> >>>>>>>>>> There are lots of arguing related to it, anyway it has pros >>> >> >>>>>>>>>> and >>> >> >>>>>>>>>> cons. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Let's take a concrete example of querying a model: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> GameSession.objects.filter(user__profile__last_login_date__gte=yesterday) >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Pros: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 1. The syntax is easy to understand >>> >> >>>>>>>>>> 2. Can be extended with custom transforms and lookups >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> However, there are several cons: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 1. Long strings is hard to read, especially if we have >>> >> >>>>>>>>>> fields >>> >> >>>>>>>>>> with >>> >> >>>>>>>>>> underscores. >>> >> >>>>>>>>>> It's really easy to make a mistake by missing one: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> GameSession.objects.filter(user_profile__last_login_date__gte=yesterday) >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Not easy to catch missing underscore between user and >>> >> >>>>>>>>>> profile, >>> >> >>>>>>>>>> is >>> >> >>>>>>>>>> it? >>> >> >>>>>>>>>> Even >>> >> >>>>>>>>>> though, it's not easy to say whether it should be >>> >> >>>>>>>>>> "user_profile" >>> >> >>>>>>>>>> attribute or >>> >> >>>>>>>>>> user.profile foreign key. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 2. Query strings can't be reused, thus the approach >>> >> >>>>>>>>>> violates >>> >> >>>>>>>>>> DRY >>> >> >>>>>>>>>> principle. >>> >> >>>>>>>>>> For example, we need to order results by last_login_date: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> GameSession.objects.filter(user__profile__last_login_date__gte=yesterday) >>> >> >>>>>>>>>>>>> \ >>> >> >>>>>>>>>> .order_by('user__profile__last_login_date') >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> We can't keep user__profile_login_date as a variable as in >>> >> >>>>>>>>>> the >>> >> >>>>>>>>>> first >>> >> >>>>>>>>>> part >>> >> >>>>>>>>>> of the >>> >> >>>>>>>>>> expression we use a keyword argument, meanwhile in the >>> >> >>>>>>>>>> second >>> >> >>>>>>>>>> part - >>> >> >>>>>>>>>> just >>> >> >>>>>>>>>> a >>> >> >>>>>>>>>> string. And thus we just have to type query path twice. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 3. Lookup names not natural to Python language and require >>> >> >>>>>>>>>> to >>> >> >>>>>>>>>> be >>> >> >>>>>>>>>> remembered or >>> >> >>>>>>>>>> looked up in documentation. For example, "__gte" or "__lte" >>> >> >>>>>>>>>> lookups >>> >> >>>>>>>>>> tend >>> >> >>>>>>>>>> to be >>> >> >>>>>>>>>> confused with "ge" and "le" due to similarity to methods >>> >> >>>>>>>>>> "__ge__" >>> >> >>>>>>>>>> and >>> >> >>>>>>>>>> "__le__". >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 4. Lookup keywords limited to a single argument only, very >>> >> >>>>>>>>>> inconvenient >>> >> >>>>>>>>>> when >>> >> >>>>>>>>>> necessary to filter objects by range. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> I was thinking a lot trying to solve those issues, keeping >>> >> >>>>>>>>>> in >>> >> >>>>>>>>>> mind >>> >> >>>>>>>>>> Django >>> >> >>>>>>>>>> approaches. Finally I came up with solution to extend Q >>> >> >>>>>>>>>> objects >>> >> >>>>>>>>>> with >>> >> >>>>>>>>>> dot >>> >> >>>>>>>>>> expression syntax: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> GameSession.objecs.filter(Q.user.profile.last_login_date >>> >> >>>>>>>>>>>>> >= >>> >> >>>>>>>>>>>>> yesterday) >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Q is a factory instance for old-style Q objects. Accessing >>> >> >>>>>>>>>> attribute >>> >> >>>>>>>>>> by >>> >> >>>>>>>>>> dot >>> >> >>>>>>>>>> returns a child factory, calling factory will instantiate >>> >> >>>>>>>>>> old-style Q >>> >> >>>>>>>>>> object. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q >>> >> >>>>>>>>>> <QFactory object at 0x7f407298ee10> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q.user.profile >>> >> >>>>>>>>>> <QFactory object at 0x7f40765da310> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q(user__name='Bob') >>> >> >>>>>>>>>> <Q: (AND: ('user__name', 'Bob'))> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> It overrides operators, so comparing factory with value >>> >> >>>>>>>>>> returns >>> >> >>>>>>>>>> a >>> >> >>>>>>>>>> related >>> >> >>>>>>>>>> Q >>> >> >>>>>>>>>> object: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q.user.name == 'Bob' >>> >> >>>>>>>>>> <Q: (AND: ('user__name', 'Bob'))> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Factory has several helper functions for lookups which >>> >> >>>>>>>>>> aren't >>> >> >>>>>>>>>> related >>> >> >>>>>>>>>> to >>> >> >>>>>>>>>> any >>> >> >>>>>>>>>> Python operators directly: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q.user.name.icontains('Bob') >>> >> >>>>>>>>>> <Q: (AND: ('user__name__icontains', 'Bob'))> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> And helper to get query path as string, which requred by >>> >> >>>>>>>>>> order_by >>> >> >>>>>>>>>> or >>> >> >>>>>>>>>> select_related queryset methods: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q.user.profile.last_login_date.get_path() >>> >> >>>>>>>>>> 'user__profile__last_login_date' >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> You can check implementation and more examples here >>> >> >>>>>>>>>> https://github.com/Nepherhotep/django-orm-sugar >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> How it solves issues: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> #1. Dots hard to confuse with underscores >>> >> >>>>>>>>>> #2. Query paths can be reused: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> factory = Q.user.profile.last_login_date >>> >> >>>>>>>>>>>>> query = GameSession.objects.filter(factory >= yesterday) >>> >> >>>>>>>>>>>>> query = query.order_by(factory.get_path()) >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> #3. Not neccessary to remember most of lookup names and use >>> >> >>>>>>>>>> comparison >>> >> >>>>>>>>>> operators >>> >> >>>>>>>>>> instead. >>> >> >>>>>>>>>> #4. Possible to use multiple keyword arguments: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> Q.user.profile.last_login_date.in_range(from_date, >>> >> >>>>>>>>>>>>> to_date) >>> >> >>>>>>>>>> <Q: (AND: ('user__profile__last_login_date__lte', >>> >> >>>>>>>>>> from_date), >>> >> >>>>>>>>>> ('user__profile__last_login_date__gte', to_date))> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> This approach looked the best for me due to several >>> >> >>>>>>>>>> reasons: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 1. It's explicit - it doesn't do anything but generating >>> >> >>>>>>>>>> appropriate >>> >> >>>>>>>>>> Q >>> >> >>>>>>>>>> object. >>> >> >>>>>>>>>> The result of comparison can be saved as Q object variable. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 2. It's short - variants with using model for that will >>> >> >>>>>>>>>> look >>> >> >>>>>>>>>> much >>> >> >>>>>>>>>> longer, >>> >> >>>>>>>>>> when >>> >> >>>>>>>>>> joining two or more filters: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> GameSession.objects.user.profile_last_login_date >= >>> >> >>>>>>>>>>>>> yesterday >>> >> >>>>>>>>>>>>> # >>> >> >>>>>>>>>>>>> awkward >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 3. Implementation will not require to change querset >>> >> >>>>>>>>>> manager or >>> >> >>>>>>>>>> model >>> >> >>>>>>>>>> classes >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> 4. Will still allow to use filters and Q class in the old >>> >> >>>>>>>>>> way: >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> q = Q(user__profile__last_login_date__gte=yesterday) >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> or >>> >> >>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> >>> >> >>>>>>>>>>>>> GameSession.objects.filter(user__profile__last_login_date__gte=yesterday) >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> I'd like to make it as a part of Django ORM syntax and it >>> >> >>>>>>>>>> will >>> >> >>>>>>>>>> not be >>> >> >>>>>>>>>> hard to >>> >> >>>>>>>>>> do, especially taking into account the library is already >>> >> >>>>>>>>>> done >>> >> >>>>>>>>>> and >>> >> >>>>>>>>>> working. >>> >> >>>>>>>>>> Anyway, I need your thought about the idea in general, as >>> >> >>>>>>>>>> well >>> >> >>>>>>>>>> as >>> >> >>>>>>>>>> about >>> >> >>>>>>>>>> particular things like chosen method names - "get_path", >>> >> >>>>>>>>>> "in_range" >>> >> >>>>>>>>>> and >>> >> >>>>>>>>>> etc. >>> >> >>>>>>>>>> As next step I can create a ticket in the issue tracker, or >>> >> >>>>>>>>>> prepare >>> >> >>>>>>>>>> DEP >>> >> >>>>>>>>>> first. >>> >> >>>>>>>>>> In latter case I need to find a shepherd to work with. >>> >> >>>>>>>>>> >>> >> >>>>>>>>>> Best regards, >>> >> >>>>>>>>>> Alexey >>> >> >>>>>>>> >>> >> >>>>>>>> -- >>> >> >>>>>>>> You received this message because you are subscribed to the >>> >> >>>>>>>> Google >>> >> >>>>>>>> Groups >>> >> >>>>>>>> "Django developers (Contributions to Django itself)" group. >>> >> >>>>>>>> To unsubscribe from this group and stop receiving emails from >>> >> >>>>>>>> it, >>> >> >>>>>>>> send >>> >> >>>>>>>> an >>> >> >>>>>>>> email to django-develop...@googlegroups.com. >>> >> >>>>>>>> To post to this group, send email to >>> >> >>>>>>>> django-d...@googlegroups.com. >>> >> >>>>>>>> Visit this group at >>> >> >>>>>>>> http://groups.google.com/group/django-developers. >>> >> >>>>>>>> To view this discussion on the web visit >>> >> >>>>>>>> >>> >> >>>>>>>> >>> >> >>>>>>>> >>> >> >>>>>>>> >>> >> >>>>>>>> https://groups.google.com/d/msgid/django-developers/3bad8371-f9b4-47ff-a681-0108b320e9b5%40googlegroups.com. >>> >> >>>>>>>> >>> >> >>>>>>>> For more options, visit https://groups.google.com/d/optout. >>> >> >>>>> >>> >> >>>>> -- >>> >> >>>>> You received this message because you are subscribed to the >>> >> >>>>> Google >>> >> >>>>> Groups >>> >> >>>>> "Django developers (Contributions to Django itself)" group. >>> >> >>>>> To unsubscribe from this group and stop receiving emails from >>> >> >>>>> it, >>> >> >>>>> send >>> >> >>>>> an >>> >> >>>>> email to django-develop...@googlegroups.com. >>> >> >>>>> To post to this group, send email to >>> >> >>>>> django-d...@googlegroups.com. >>> >> >>>>> Visit this group at >>> >> >>>>> http://groups.google.com/group/django-developers. >>> >> >>>>> To view this discussion on the web visit >>> >> >>>>> >>> >> >>>>> >>> >> >>>>> >>> >> 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