2 Rails Quirks


#1

I have two problems with my Rails code that seem like they should be
easy fixes but I can’t figure it out. Anyone looking at the code below
will probably think it looks weird or redundant but it’s the only way
I’ve gotten it to work. I’d rather do it right though. The first
problem is that I have to define the ID outside of the call to new. If
I define the ID in new, it never gets defined for whatever reason and
I get a not null constraint violation on productid. Why is it that I
have to define it outside of new to make it work? The second problem
is the call to save. My understanding of save is that it creates a new
record if no matching record exists, otherwise it updates the matching
record. Well, for some reason I keep getting:

Exception encountered: RuntimeError: ERROR C23505 Mduplicate key
violates unique constraint supplier_stock_pkey" Fnbtinsert.c
L255 R_bt_check_unique: INSERT INTO supplier_stock (“productid”,
yesterday_stock", “current_stock”) VALUES(525542, 0, -1)

Why is it not updating instead of trying to create a new record?
Thanks.

Working code:

begin
  product = SupplierStock.new(
    :current_stock => s
  )
  product[:productid] = prodid
  product.save
  end
rescue Exception => e
  SupplierStock.update(
    prodid,
    {:current_stock => s}
  )
end

#2

record. Well, for some reason I keep getting:

   {:current_stock => s}
 )

end

How come the primary key for your table is “productid” and not just “id”
?
Did you change that in your SupplierStock model? Assuming you did…

Why arey ou creating a new SupplierStock when you have a prodid
instead
of finding the record associated with that prodid?

Save will do the right thing, but not if you try and create a new
record
and then set the primary key to an existing record.

I think the code you want above should be closer to this:

product = SupplierStock.find_by_productid(prodid)
product.current_stock = s
product.save

-philip


#3

product = SupplierStock.find_by_productid(prodid)
product.current_stock = s
product.save

-philip

Great, thanks! That fixed the second problem… any ideas on the
first? I still get a not-null constraint violation on productid on the
create call below. And yes, the primary key is defined as productid in
the SupplierStock model.

New Code:

  product = SupplierStock.find_by_productid(prodid)
  if product
    product.current_stock = s
    product.save
  else
    SupplierStock.create(
      :id      => prodid,
      :current_stock  => s
    )
  end

#4

On Jul 25, 11:19 am, Dave S. removed_email_address@domain.invalid
wrote:

Could you post actual error message and the code that generates it? It
also couldn’t hurt to post the relevant snippets from the
supplier_stock.rb and the migration.

Posted viahttp://www.ruby-forum.com/.

Error occurs on the call to create:

CODE:

  product = SupplierStock.find_by_productid(prodid)
  if product
    product.current_stock = s
    product.save
  else
    product = SupplierStock.create(
      :id             => prodid,
      :current_stock  => s
    )
  end

ERROR:

Exception encountered: RuntimeError: ERROR C23502 Mnull value in
column “productid” violates not-null constraint FexecMain.c
L1782 ExecConstraints: INSERT INTO supplier_stock
(“yesterday_stock”, “current_stock”) VALUES(0, 0)

SupplierStock Class:

class SupplierStock < ActiveRecord::Base

def self.table_name()
“supplier_stock”
end

def self.primary_key()
“productid”
end

end

Table Schema:

     Table "public.supplier_stock"
 Column      |  Type   |     Modifiers

-----------------±--------±-------------------
productid | integer | not null
current_stock | integer | not null default 0
yesterday_stock | integer | not null default 0
Indexes:
“supplier_stock_pkey” primary key, btree (productid)
Foreign-key constraints:
“$1” FOREIGN KEY (productid) REFERENCES
supplier_products(productid) ON DELETE CASCADE


#5

On Jul 25, 2007, at 1:14 PM, Matt W. wrote:

and then set the primary key to an existing record.
first? I still get a not-null constraint violation on productid on the
SupplierStock.create(
:id => prodid,
:current_stock => s
)
end

SupplierStock.find_or_create_by_productid(prodid).update_attribute
(:current_stock, s)

It will hit the database twice (select + update) or three times
(select + insert + update) depending on whether the SupplierStock
record exists or not, respectively, but if creation is relatively
rare with respect to existence, it’s probably not too bad.

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid


#6

Could you post actual error message and the code that generates it? It
also couldn’t hurt to post the relevant snippets from the
supplier_stock.rb and the migration.


#7

On Jul 25, 2007, at 1:39 PM, Matt W. wrote:

    )
  end

ERROR:

Exception encountered: RuntimeError: ERROR C23502 Mnull value in
column “productid” violates not-null constraint FexecMain.c
L1782 ExecConstraints: INSERT INTO supplier_stock
(“yesterday_stock”, “current_stock”) VALUES(0, 0)

SupplierStock Class:

I think you need to let ActiveRecord know where you’re departing from
convention.

class SupplierStock < ActiveRecord::Base

set_table_name “supplier_stock”
set_primary_key “productid”

Table Schema:
“$1” FOREIGN KEY (productid) REFERENCES
supplier_products(productid) ON DELETE CASCADE

You might also need to do the create step like:

unless prodid.nil?
if product = SupplierStock.find_by_id(prodid)
product.update_attribute(:current_stock, s)
else
product = SupplierStock.new do |ss|
ss.id = prodid
ss.current_stock = s
end
product.save
end
end

I don’t think you can specify the :id on a create, but you can alter
the :id before the new record is saved. In your case, however, you
seem to have prodid.nil? to start and that can’t be what you expect.

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid


#8

Same problem with the dynamic find_by statement:

CODE:
product = SupplierStock.find_or_create_by_productid(prodid)

ERROR:
Exception encountered: RuntimeError: ERROR C23502 Mnull value in
column “productid” violates not-null constraint FexecMain.c
L1782 ExecConstraints: INSERT INTO supplier_stock
(“yesterday_stock”, “current_stock”) VALUES(0, 0)


#9

On Jul 25, 12:22 pm, Rob B. removed_email_address@domain.invalid
wrote:


else
L1782 ExecConstraints: INSERT INTO supplier_stock
set_primary_key “productid”

Indexes:
else
seem to have prodid.nil? to start and that can’t be what you expect.

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid

Thanks for your help Rob. Here’s what I’m sticking with:

  if product = SupplierStock.find_by_productid(prodid)
    product.update_attribute(:current_stock, s)
  else
    product = SupplierStock.new { |ss|
      ss.id = prodid
      ss.current_stock = s
    }
    product.save
  end

Seems to work fine. But I still never learned why you can’t specify
the id when you make a new ActiveRecord object. Here’s a snipped from
my script/console with what I mean:

product = SupplierStock.new({:id => 600000, :current_stock => 3})
=> #<SupplierStock:0x6881cc8 @new_record=true,
@attributes={“yesterday_stock”=>0, “current_stock”=>3}>

You can see that the ID is not included in @attributes above

product.id = 600000
=> 600000

product
=> #<SupplierStock:0x6881cc8 @new_record=true,
@attributes={“productid”=>600000, “yesterday_stock”=>0,
“current_stock”=>3}>

But now that I specified it OUTSIDE the call to new, it is present.


#10

The id attribute, like other attr_protected attributes, is protected
from mass assignment by hash. You must assign it individually.

make product_id just a regular indexed field and not the primary key.
Then you can change all that nonsense above to:

product = SupplierStock.find_or_create_by_product_id(600000,
:current_stock => 3)

Rick O.
http://lighthouseapp.com
http://weblog.techno-weenie.net
http://mephistoblog.com


#11

Unfortunately, I did not define the schema - just hired into it. They
have a whole platform built on this table so changing it isn’t just a
trivial thing. But at least I understand what’s going on now. Thanks!


#12

Matt W. wrote:

Seems to work fine. But I still never learned why you can’t specify
the id when you make a new ActiveRecord object. Here’s a snipped from
my script/console with what I mean:

product = SupplierStock.new({:id => 600000, :current_stock => 3})
=> #<SupplierStock:0x6881cc8 @new_record=true,
@attributes={“yesterday_stock”=>0, “current_stock”=>3}>

You can see that the ID is not included in @attributes above

The id attribute, like other attr_protected attributes, is protected
from mass assignment by hash. You must assign it individually.


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