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Re: [Artanis] Foreign Key for Migrations

From: Nala Ginrut
Subject: Re: [Artanis] Foreign Key for Migrations
Date: Sun, 14 Apr 2019 13:29:55 +0800
User-agent: mu4e 1.0; emacs 25.1.1

Hi Jonathan!

Jonathan Schmeling writes:

> Thanks a ton for the explanation!
> Still model-related, how might one pick two columns as primary keys for 
> models?

I'm not very sure I understand your question. I guess you're asking
about how to specify multi-primary-keys in migration/models. If so, then
you should try this (we take migration as an example, but models are

  '(id big-integer)
  '(name char-field (#:not-null #:maxlen 10))
  '(age tiny-integer (#:not-null))
  '(email char-field (#:maxlen 20))
  #:primary-keys '(name id)))

Please notice that you can only specify all primiary-keys in
#:primary-keys, if you also specify "id" as "auto" type, then it'll will
be expand to primary-key either. Then the SQL will throw exception. And
this is not the mechanism of Artanis, it's SQL.

BTW, I feel embarrass that this #:primary-keys feature was actually
missing in Artanis although I thought I've done it. Then I realized the
problem when you mention it. ;-)
I've fixed it in commit 812197ea77f048a, please pull and try.

> And, – on that note – I know you mentioned foreign relational mapping 
> still needing some work to be developed. I don't know how useful I can 
> be (most of Artanis's source code still goes over my head, a bit) but, 
> if I can be of help, I'd love to give back what I can.

For the design of non-foreign-keys, I'm still researching to find a
better way. If you want to help, I think in this moment, try to use
Artanis and report will be great contributions. Because I can't cover
every corner cases, although I've done many features, I can't guarrentee
they work as expected, it requires more tests and reports from users.

Anyway, thank you very much!
Best regards.

> Jonathan
> On 3/24/19 1:46 AM, Nala Ginrut wrote:
>> Hi Jonathan!
>> Jonathan Schmeling writes:
>>> In the mean time, what is the difference between the migration and
>>> models since I have a feeling I don't fully understand. Is it just that
>>> models will handle creating the tables, now, rather than migrations but
>>> migrations are still useful for creating dummy/test data in the tables?
>> Actually, migration and models are sharing the same implemtation
>> mechanism in the low-level. But there're 2 differences:
>> 1. They're slightly different in syntax, migration doesn't use macros of
>> Scheme, so you have to add quote-sign "'" explicitly. This is trivial.
>> 2. They're different for the purpose. Migration is a tool to migrate DB
>> data, or easily handling when you're still designing your tables. You
>> may change the definition as you wish, and run it arbitrarily. The
>> tables in migration will not be recognized by Artanis, it's just for
>> creating/dropping or transferring data.
>> Models are the mapping to the existing tables after you confirmed your
>> design. And should be cautiously changed, because I will add
>> verification mechanism in the future. That is to say, the definition
>> that you put in model will be recognized by Artanis. If you've defined a
>> table in model, it will be created if it doesn't exist yet, but if it
>> exists, Artanis will verify its schema with your definition to make
>> sure that the table you want.
>> Best regards.
>>> Jonathan
>>> On 3/18/19 12:53 PM, Nala Ginrut wrote:
>>>> Jonathan Schmeling writes:
>>>>> web_1  | app/models/PEOPLE.scm:4:0: In procedure module-lookup: Unbound 
>>>>> variable: PEOPLE
>>>> For this issue, please update to the latest commit, I just fixed few
>>>> hours ago. However, you shouldn't encounter this issue since I've told
>>>> you to define the people table in app/models/PEOPLE.scm.
>>>> So even after fix, it will throw an error to force you define PEOPLE.
>>>> PS: Define it in the migration is useless here, since migration and
>>>> model are different things.
>>>>> web_1  | Backtrace:
>>>>> web_1  |            0 (primitive-load "/myapp/app/controllers/#{}#.scm")
>>>>> web_1  |
>>>>> web_1  | ERROR: In procedure primitive-load:
>>>>> web_1  | In procedure open-file: No such file or directory: 
>>>>> "/myapp/app/controllers/#{}#.scm"
>>>> This issue is unrelated to models, it means you've created a controller
>>>> whose name is a null string. I don't know how you made it, but you need to
>>>> check your code.
>>>>> But I'm not certain what to make of this error, unfortunately.
>>>>> Jonathan
>>>>> On Sunday, March 17, 2019, 2:49:49 PM CDT, Nala Ginrut <address@hidden> 
>>>>> wrote:
>>>>> Hi Jonathan!
>>>>> I've realized that there's bug in models after I fixed some bugs in
>>>>> migration before.
>>>>> Now I think it's fixed in a88c7e189a6a6273399e6e713be407ef55938f65
>>>>> Please notice that you're forced to define the table in
>>>>> define-artanis-model from now on, if you just leave it as
>>>>> (define-artanis-model people) after drawing a model, then
>>>>> art command will throw error.
>>>>> Here's an example:
>>>>> ----------------code------------------
>>>>> (create-artanis-model
>>>>> people
>>>>> (id auto (#:not-null #:primary-key))
>>>>> (first_name char-field (#:maxlen 30 #:not-null))
>>>>> (last_name char-field (#:maxlen 30 #:not-null)))
>>>>> ----------------end-------------------
>>>>> And another notion is that the syntax is slightly different from the
>>>>> mogration, in migration, you should use symbol explicitly:
>>>>> -----------------code---------------------
>>>>> (create-table
>>>>> 'people
>>>>> '(id auto (#:not-null #:primary-key))
>>>>> '(first_name char-field (#:maxlen 30 #:not-null))
>>>>> '(last_name char-field (#:maxlen 30 #:not-null)))
>>>>> -----------------end----------------------
>>>>> But in Models, the list is quasiquote, so you can use unquote-sign, say
>>>>> "," to escape the content if you like.
>>>>> Please try it, and don't hasitate to report bugs. ;-)
>>>>> Thanks!
>>>>> Jonathan Schmeling writes:
>>>>>> Thanks so much for the response! Ahhh; I did wonder if Artanis had 
>>>>>> anything had anything like that. That is really nice to work with.
>>>>>> So I have a table named PEOPLE; so I ran art draw model PEOPLE and that 
>>>>>> reated a file named PEOPLE.scm which contains
>>>>>> ;; Model PEOPLE definition of myapp
>>>>>> ;; Please add your license header here.
>>>>>> ;; This file is generated automatically by GNU Artanis.
>>>>>> (create-artanis-model PEOPLE) ; DO NOT REMOVE THIS LINE!!!
>>>>>> I then added to one of my controllers (use-modules (app models PEOPLE)) 
>>>>>> and running Artanis and visiting endpoints in that controller didn't 
>>>>>> throw any errors.
>>>>>> So then I added a call similar to the one you had that uses ($PEOPLE …) 
>>>>>> in the controller; however, then I get the error In procedure 
>>>>>> module-lookup: Unbound variable: $PEOPLE when I visit the endpoint that 
>>>>>> uses the function call.
>>>>>> Did I miss something?
>>>>>> Jonathan
>>>>>> On Saturday, March 16, 2019, 3:31:19 PM CDT, Nala Ginrut 
>>>>>> <address@hidden<mailto:address@hidden>> wrote:
>>>>>> Hi Jonathan!
>>>>>> Sorry it's my mistake to neglect this part in the doc.
>>>>>> You don't have to take care of the DB connection management by
>>>>>> yourself. You may just use `art draw model person' to create the named
>>>>>> mapping to the "person" table, and there's an exported relational
>>>>>> mapping object named "$person", you may import (app models person) in
>>>>>> other controller to use it. It's based on FPRM, but the table name has
>>>>>> already been wrapped into the closure:
>>>>>> And maybe read its implementation is clearer to you:
>>>>>> The usage should look like this:
>>>>>> ($person 'set #:name "nala" #:age 100)
>>>>>> BTW, please don't forget to config your DB in conf/artanis.conf first.
>>>>>> Best regards.
>>>>>> Jonathan Schmeling writes:
>>>>>>> Gotcha. That makes a lot of sense. Thanks a ton for explaining!
>>>>>>> Database related, is there a way to query the database from one of the 
>>>>>>> controller -define methods (like (article-define show …) in the online 
>>>>>>> documentation)? Using the function map-table-from-DB causes an error 
>>>>>>> and attaching #:conn #t, like with the get function, also causes an 
>>>>>>> error. Doing something like (:conn rc "SELECT * FROM PEOPLE") seems to 
>>>>>>> work (or, at least, not throw an error) but I'm not sure what gets 
>>>>>>> returned. The doc. says the returned value is described at 
>>>>>>> but 
>>>>>>> that section says "TODO".
>>>>>>> As always, any help is always super appreciated!
>>>>>>> Jonathan
>>>>>>> On 2/17/19 12:19 PM, Nala Ginrut wrote:
>>>>>>> Hi Jonathan!
>>>>>>> I'm glad you asked this question.
>>>>>>> The answer is actually written in the fprm.scm code comments that the
>>>>>>> relational mapping in Artanis is not going to provide database level
>>>>>>> foreign keys. The solution is to provide higher-abstract-level table
>>>>>>> operations as a replacement to save users to time to handle by
>>>>>>> themselves.
>>>>>>> The pros and cons of foreign keys are discussed a lot in the
>>>>>>> internet. The modern ORM may choose to drop foreign keys and provide
>>>>>>> higher layer for it.
>>>>>>> Unfortunately, this feature has not been implemented yet because of my 
>>>>>>> time schedule.
>>>>>>> Of course, this issue is still open, the original plan is more
>>>>>>> ambitious. I think it's the time to add more features to the relational
>>>>>>> mapping framework.
>>>>>>> Welcome to discuss if you like.
>>>>>>> Best regards.
>>>>>>> Jonathan Schmeling writes:
>>>>>>> I'm not sure if it's been asked before but I couldn't find any mention
>>>>>>> in the doc. – is it feasible to define foreign keys for the create-table
>>>>>>> function? I want to reference another table's primary keys from a
>>>>>>> particular table, to link them.
>>>>>>> Jonathan
>>>> --
>>>> GNU Powered it
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>>>> HFG - NalaGinrut
>>>> Fingerprint F53B 4C56 95B5 E4D5 6093 4324 8469 6772 846A 0058
>> --
>> GNU Powered it
>> GPL Protected it
>> GOD Blessed it
>> HFG - NalaGinrut
>> Fingerprint F53B 4C56 95B5 E4D5 6093 4324 8469 6772 846A 0058

GNU Powered it
GPL Protected it
GOD Blessed it
HFG - NalaGinrut
Fingerprint F53B 4C56 95B5 E4D5 6093 4324 8469 6772 846A 0058

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