I wasn't aware that Linkable took different types of joins. On Tuesday, 22 July 2014 11:50:38 UTC+1, José Lorenzo wrote: > > Not sure why linkable is not working for you. Did you make sure to set > 'type' => 'INNER' in the linkable definition for that model? That will > filter records from the parent model according to the conditions in the > association. > > On Tuesday, July 22, 2014 10:57:14 AM UTC+2, David Yell wrote: >> >> *Synopsis* >> Trying to select data from multiple related models explicitly is hard in >> the framework due to it's focus on always providing a left join. Even with >> Containable and Linkable it's not always possible, without a manual query, >> to select records where their related record has a condition. Such as >> selecting all Posts where a Tag is authored by User x. It seems odd to me >> that the framework should return empty related model records or, if using >> linkable not return all the related records. I am starting this thread to >> discuss solutions, tips, tricks and techniques for achieving this >> functionality as I do not feel that either Containable or Linkable >> accurately cover this use-case. It may well be that case that some more >> guidance is needed in the documentation for this specific type of query. >> >> *The problem* >> You would like to select from primary model but only if related models >> conditions are met. The primary model should only be included in the result >> set if the related model conditions are met. With a single related model >> this is quite easy using Linkable. However when you start trying to achieve >> this across HABTM, hasManyThrough or two or three nested models the problem >> grows in complexity. >> >> A few examples, might make things clearer. >> >> *Hotel hasMany HotelFeature belongsTo Feature* >> You need to select hotels which have n number of specific features. The >> hotel must have all of the features listed to be included in the dataset. >> >> *Post hasMany PostsTag belongsTo Tag belongsTo User* >> You need to find all the posts which have tags created by a certain user. >> >> *Hotel belongsTo City belongsTo Province belongsTo Country* >> You need to select all the cities in a country where there is a hotel. >> >> I'm sure there are some other use-cases, but these are the ones of the >> top of my head. As you can see it's usually selecting a primary record >> where a related record matches a certain condition, but where the related >> record is a multiple. >> >> *Possible solutions* >> This is where I am unsure. My SQL-fu is weak thanks to Cake's awesome >> ORM. The only real thing that I can think of is either more enhancements to >> Containable or Linkable really. However I am not sure how to approach such >> a problem. I was told once in an interview that any more than five joins >> will impact performance in MySQL (could be fiction), so obviously there is >> a performance concern with highly normalised databases. Concerns which are >> ignored by Containable with it's multiple queries across many models - a >> solution which I think was devised to solve this problem. >> >> *Discussion* >> The idea of the thread was to discuss potential solutions really. I >> wanted to air my thoughts on a problem which I have hit many times with my >> current project and have had to battle against. Usually using manual joins, >> but in most cases I end up using Containable and filtering the data in the >> front-end `foreach()` which isn't elegant, clever or clean. >> >> I'm sure this kind of issue will have been addressed with the new ORM in >> 3.x, but I need to find a decent solution to this problem which will be >> flexible enough to be beneficial to lots of different projects, and to >> other Cake users. We are all taught to normalise, and it makes sense to do >> so, but this issue keeps nagging at me and I'm finding it frustrating. I >> don't feel that the framework is helping me solve such a problem. >> >> If you read to here, thanks, have a biscuit and share your thoughts. How >> do you get around this issue? >> >
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