Re: Stuck - Join limitation in 1.2?
(Thanks for the note about my article -- I cleaned up the wording a little to cause less confusion) I thought along the exact same lines, thinking that belongsTo would better be referred to as hasOne, until I realized that I was getting stuck on how I assumed the semantics worked, according to how I would express the relationships in words. For me, the understanding all hinged on the concepts of ownership, and which action is "active": having or belonging (by active I mean doing the pointing -- referencing the other table with a field). You seem to be looking at relationships from the perspective of knowledge -- which object knows about the other. If this were the case, then your argument about the Thing not knowing anything about the Person would stand -- but CakePHP and most relational systems don't look at associations from that perspective, but rather from an ownership perspective. Remember this concept: Ownership is a property of the possession. That is to say, that the secondary or associated data is responsible for referencing the primary data, not the other way around. The possession belongs to the possessor. The possession is the item "doing" something -- the belonging. So then, the possessor is passive in the relationship. Ownership is passive, whereas membership is active. This is why it is the duty of the table with the possession to reference the table of the possessor. Having is best thought of as a passive state -- the table that "has" does not reference the tables who relate to it. If you're describing the relationship of a Person owning a Thing, since ownership is a property of the possession, the Thing will belongTo the Person (having a field in the Thing table which references a person). And conversely, the Person has(One|Many) Thing(s). Your implementation will always be dictated by the parameters within which you are operating. So if you're writing an app in an environment that describes the data differently than CakePHP's conventions -- you do what you have to do. But this does not mean that the semantics of the associations CakePHP applies are incorrect, but perhaps from a different perspective. -- Joshua Benner http://bennerweb.com --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Cake PHP" group. To post to this group, send email to cake-php@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/cake-php?hl=en -~--~~~~--~~--~--~---
Re: Stuck - Join limitation in 1.2?
Thanks for the reply Joshua On Jun 12, 8:21 pm, Joshua Benner <[EMAIL PROTECTED]> wrote: > To, it sounds like: > > Person belongsTo Country > > I'd use a belongsTo relationship in the Person model. Correct, this was a bad example, and in this case I'd tend to agree and that type of relationship does work. Replacing "Country" with "Thing", and considering that each person has a "Thing" is closer to what I was thinking. "Things" know nothing about people, and are just things. Each person will always have just one thing, so we don't need the flexibility of a join table to associate an arbitrary number of Things with a person. A belongsTo relationship will do the job but seems incorrect as in this case a Person has a Thing, and a Person does not belong to a Thing. What is the case though is that the actual value in the Thing column of a Person does belong to Things, and if we consider that then it does make sense. So whilst Person as a whole does not belong to Thing, the Thing *value* of a Person does belong to Thing. Another example would be Colour, where all manner of models might have Colour as an attribute, but the models would not belong to colour. > I wrote a bit on understanding the practical differences between > relationships here:http://bennerweb.com/node/16 This is a great article, although you show why there is the confusion when you write "each movie has one director" but then model that relationship with belongsTo and not hasOne :) Aside from the fact that belongsTo would work and hasOne wouldn't, as a movie is the creative work of a director it would be fair enough to consider that a movie belongs to a director, but in some cases I feel that hasOne would be the clearer and more natural choice as this is how we would explain the model to someone. It's evidently unnecessary for an enhancement to hasOne, however for the sake of expressiveness, being able to use hasOne or perhaps an "isA" concept might be clearer. Thanks again for the helpful reply though. Nick --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Cake PHP" group. To post to this group, send email to cake-php@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/cake-php?hl=en -~--~~~~--~~--~--~---
Re: Stuck - Join limitation in 1.2?
To, it sounds like: Person belongsTo Country I'd use a belongsTo relationship in the Person model. And if you need to do Country->People lookups, put a reverse hasMany in the country model. I wrote a bit on understanding the practical differences between relationships here: http://bennerweb.com/node/16 Nick wrote: > Hi > > We're exploring CakePHP, and I'm stuck on how to describe the > following model relationship. It should be trivial and I'm sure that > I'm missing something, but precisely what eludes me. Can anyone help? > > Let's say that we have a model 'Person', and one of the attributes for > Person is "country". The value of country is the primary key into a > table of Countries. $hasOne can express that Person should join on > Countries, but the join is made against Person.id, and I cannot find a > way to express that the field in Person to use for the join is > country. > > Checking the archives, floepi posted a tweak back in January to add an > associatedKey attribute for $hasOne to express this notion, but I > wondered whether something like this is now standard in 1.2. > > Cheers > Nick > > > > > -- Joshua Benner http://bennerweb.com --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Cake PHP" group. To post to this group, send email to cake-php@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/cake-php?hl=en -~--~~~~--~~--~--~---
Stuck - Join limitation in 1.2?
Hi We're exploring CakePHP, and I'm stuck on how to describe the following model relationship. It should be trivial and I'm sure that I'm missing something, but precisely what eludes me. Can anyone help? Let's say that we have a model 'Person', and one of the attributes for Person is "country". The value of country is the primary key into a table of Countries. $hasOne can express that Person should join on Countries, but the join is made against Person.id, and I cannot find a way to express that the field in Person to use for the join is country. Checking the archives, floepi posted a tweak back in January to add an associatedKey attribute for $hasOne to express this notion, but I wondered whether something like this is now standard in 1.2. Cheers Nick --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Cake PHP" group. To post to this group, send email to cake-php@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/cake-php?hl=en -~--~~~~--~~--~--~---
