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Re: [Artanis] Foreign Key for Migrations

From: Nala Ginrut
Subject: Re: [Artanis] Foreign Key for Migrations
Date: Tue, 19 Mar 2019 01:53:18 +0800
User-agent: mu4e 1.0; emacs 25.1.1

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

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