Re: django-firebird test expressions

[Maximiliano Robaina]

El martes, 17 de abril de 2018, 9:11:23 (UTC-3), Josh Smeaton escribió:
>
> Have you looked into using Cast for this particular query to see if it 
> passes?
>
> https://docs.djangoproject.com/en/2.0/ref/models/database-functions/#cast
>
> Cast(RawSQL('%s', ['value']), CharField(max_length=10) ?
>
> If that worked, then perhaps you could find a clever way to wrap problem 
> expressions, or at least document the workaround for your users.
>

Ok, it worked rigth. It is a good started point and solve the problem. 
I will need to dig a little more to found out a better solution.

Thanks.






 

>
> On Tuesday, 17 April 2018 21:12:09 UTC+10, Maximiliano Robaina wrote:
>>
>>
>> Hi Shai,
>>
>> Thank for the tip
>>
>> El martes, 17 de abril de 2018, 3:01:30 (UTC-3), Shai Berger escribió:
>>>
>>> Hi Maximiliano, 
>>>
>>> On Sat, 14 Apr 2018 19:25:48 -0700 (PDT) 
>>> Maximiliano Robaina  wrote: 
>>>
>>> > Hi, 
>>> > 
>>> > Testing expressions test app, the query generated into 
>>> > BasicExpressionsTests.test_annotate_values_filter method: 
>>> > 
>>> > companies = Company.objects.annotate( 
>>> > foo=RawSQL('%s', ['value']), 
>>> > ).filter(foo='value').order_by('name') 
>>> > 
>>> > Generate: 
>>> > 
>>> > 'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
>>> > "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES", 
>>> > "EXPRESSIONS_COMPANY"."NUM_CHAIRS", "EXPRESSIONS_COMPANY"."CEO_ID", 
>>> > "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
>>> > "EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY 
>>> > "EXPRESSIONS_COMPANY"."NAME" ASC' 
>>> > 
>>> > This sql command has 3 params (?), two of which are out of where 
>>> > clause. 
>>> > 
>>> > ? AS "FOO" 
>>> > 
>>> > WHERE ? = ? 
>>> > 
>>>
>>> A few years ago something similar was causing issues with the Oracle 
>>> backend. To resolve it, Mariusz added a clevar hack, relying on named 
>>> parameters -- he made sure that if the same parameter value is used 
>>> more than once, then the statement re-uses the parameter name, passing 
>>> the value only once. So, in your case, the equivalent would be 
>>> something like 
>>>
>>> ... 
>>> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", %arg1 AS "FOO" FROM 
>>> "EXPRESSIONS_COMPANY" WHERE %arg1 = %arg1 ORDER BY 
>>> "EXPRESSIONS_COMPANY"."NAME" ASC' 
>>>
>>> with 
>>>
>>>  cursor.execute(sql, [], arg1='value') 
>>>
>>> This was relatively easy to do in the Oracle backend, which has always 
>>> used named parameters under the hood (though the idea to do it was, in 
>>> my opinion, surprising and brilliant). If Firebird supports them, you 
>>> may be able to borrow this solution. 
>>>
>>> Shai 
>>>
>>
>> Ok, but it is a cx_Oracle implementation.
>> Unfortunately fdb (the firebird python driver) doesn't support this and, 
>> in any case, is a FirebirdSQL limitation. [1]
>>
>> Regards.
>>
>>
>> [1]  
>> https://stackoverflow.com/questions/37348807/data-type-unknown-in-case-expression-with-only-parameters-as-values
>>
>>  
>>
>

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Re: django-firebird test expressions

[Josh Smeaton]

Have you looked into using Cast for this particular query to see if it 
passes?

https://docs.djangoproject.com/en/2.0/ref/models/database-functions/#cast

Cast(RawSQL('%s', ['value']), CharField(max_length=10) ?

If that worked, then perhaps you could find a clever way to wrap problem 
expressions, or at least document the workaround for your users.

On Tuesday, 17 April 2018 21:12:09 UTC+10, Maximiliano Robaina wrote:
>
>
> Hi Shai,
>
> Thank for the tip
>
> El martes, 17 de abril de 2018, 3:01:30 (UTC-3), Shai Berger escribió:
>>
>> Hi Maximiliano, 
>>
>> On Sat, 14 Apr 2018 19:25:48 -0700 (PDT) 
>> Maximiliano Robaina  wrote: 
>>
>> > Hi, 
>> > 
>> > Testing expressions test app, the query generated into 
>> > BasicExpressionsTests.test_annotate_values_filter method: 
>> > 
>> > companies = Company.objects.annotate( 
>> > foo=RawSQL('%s', ['value']), 
>> > ).filter(foo='value').order_by('name') 
>> > 
>> > Generate: 
>> > 
>> > 'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
>> > "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES", 
>> > "EXPRESSIONS_COMPANY"."NUM_CHAIRS", "EXPRESSIONS_COMPANY"."CEO_ID", 
>> > "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
>> > "EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY 
>> > "EXPRESSIONS_COMPANY"."NAME" ASC' 
>> > 
>> > This sql command has 3 params (?), two of which are out of where 
>> > clause. 
>> > 
>> > ? AS "FOO" 
>> > 
>> > WHERE ? = ? 
>> > 
>>
>> A few years ago something similar was causing issues with the Oracle 
>> backend. To resolve it, Mariusz added a clevar hack, relying on named 
>> parameters -- he made sure that if the same parameter value is used 
>> more than once, then the statement re-uses the parameter name, passing 
>> the value only once. So, in your case, the equivalent would be 
>> something like 
>>
>> ... 
>> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", %arg1 AS "FOO" FROM 
>> "EXPRESSIONS_COMPANY" WHERE %arg1 = %arg1 ORDER BY 
>> "EXPRESSIONS_COMPANY"."NAME" ASC' 
>>
>> with 
>>
>>  cursor.execute(sql, [], arg1='value') 
>>
>> This was relatively easy to do in the Oracle backend, which has always 
>> used named parameters under the hood (though the idea to do it was, in 
>> my opinion, surprising and brilliant). If Firebird supports them, you 
>> may be able to borrow this solution. 
>>
>> Shai 
>>
>
> Ok, but it is a cx_Oracle implementation.
> Unfortunately fdb (the firebird python driver) doesn't support this and, 
> in any case, is a FirebirdSQL limitation. [1]
>
> Regards.
>
>
> [1]  
> https://stackoverflow.com/questions/37348807/data-type-unknown-in-case-expression-with-only-parameters-as-values
>
>  
>

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Re: django-firebird test expressions

[Maximiliano Robaina]

Hi Shai,

Thank for the tip

El martes, 17 de abril de 2018, 3:01:30 (UTC-3), Shai Berger escribió:
>
> Hi Maximiliano, 
>
> On Sat, 14 Apr 2018 19:25:48 -0700 (PDT) 
> Maximiliano Robaina  wrote: 
>
> > Hi, 
> > 
> > Testing expressions test app, the query generated into 
> > BasicExpressionsTests.test_annotate_values_filter method: 
> > 
> > companies = Company.objects.annotate( 
> > foo=RawSQL('%s', ['value']), 
> > ).filter(foo='value').order_by('name') 
> > 
> > Generate: 
> > 
> > 'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
> > "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES", 
> > "EXPRESSIONS_COMPANY"."NUM_CHAIRS", "EXPRESSIONS_COMPANY"."CEO_ID", 
> > "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
> > "EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY 
> > "EXPRESSIONS_COMPANY"."NAME" ASC' 
> > 
> > This sql command has 3 params (?), two of which are out of where 
> > clause. 
> > 
> > ? AS "FOO" 
> > 
> > WHERE ? = ? 
> > 
>
> A few years ago something similar was causing issues with the Oracle 
> backend. To resolve it, Mariusz added a clevar hack, relying on named 
> parameters -- he made sure that if the same parameter value is used 
> more than once, then the statement re-uses the parameter name, passing 
> the value only once. So, in your case, the equivalent would be 
> something like 
>
> ... 
> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", %arg1 AS "FOO" FROM 
> "EXPRESSIONS_COMPANY" WHERE %arg1 = %arg1 ORDER BY 
> "EXPRESSIONS_COMPANY"."NAME" ASC' 
>
> with 
>
>  cursor.execute(sql, [], arg1='value') 
>
> This was relatively easy to do in the Oracle backend, which has always 
> used named parameters under the hood (though the idea to do it was, in 
> my opinion, surprising and brilliant). If Firebird supports them, you 
> may be able to borrow this solution. 
>
> Shai 
>

Ok, but it is a cx_Oracle implementation.
Unfortunately fdb (the firebird python driver) doesn't support this and, in 
any case, is a FirebirdSQL limitation. [1]

Regards.


[1]  
https://stackoverflow.com/questions/37348807/data-type-unknown-in-case-expression-with-only-parameters-as-values

 

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Re: django-firebird test expressions

[Shai Berger]

Hi Maximiliano,

On Sat, 14 Apr 2018 19:25:48 -0700 (PDT)
Maximiliano Robaina  wrote:

> Hi,
> 
> Testing expressions test app, the query generated into 
> BasicExpressionsTests.test_annotate_values_filter method:
> 
> companies = Company.objects.annotate(
> foo=RawSQL('%s', ['value']),
> ).filter(foo='value').order_by('name')
> 
> Generate:
> 
> 'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
> "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES",
> "EXPRESSIONS_COMPANY"."NUM_CHAIRS", "EXPRESSIONS_COMPANY"."CEO_ID", 
> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
> "EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY
> "EXPRESSIONS_COMPANY"."NAME" ASC'
> 
> This sql command has 3 params (?), two of which are out of where
> clause.
> 
> ? AS "FOO" 
> 
> WHERE ? = ?
> 

A few years ago something similar was causing issues with the Oracle
backend. To resolve it, Mariusz added a clevar hack, relying on named
parameters -- he made sure that if the same parameter value is used
more than once, then the statement re-uses the parameter name, passing
the value only once. So, in your case, the equivalent would be
something like 

...
"EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", %arg1 AS "FOO" FROM 
"EXPRESSIONS_COMPANY" WHERE %arg1 = %arg1 ORDER BY
"EXPRESSIONS_COMPANY"."NAME" ASC'

with

 cursor.execute(sql, [], arg1='value')

This was relatively easy to do in the Oracle backend, which has always
used named parameters under the hood (though the idea to do it was, in
my opinion, surprising and brilliant). If Firebird supports them, you
may be able to borrow this solution.

Shai

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Re: django-firebird test expressions

[Maximiliano Robaina]

Hi Josh,

Thanks for response.

El domingo, 15 de abril de 2018, 20:35:54 (UTC-3), Josh Smeaton escribió:
>
> It looks correct to me. RawSQL is defining a parameter to be included in 
> the query. The RawSQL expression itself is used in the select and on the 
> left hand side of the WHERE clause, so the parameter needs to be included 
> there. The right hand side of the WHERE clause is a regular string (which 
> just happens to also be named "value") which Django will always 
> parameterise and has nothing to do with the RawSQL expression itself.
>
> Is there some reason you think there's an issue with the SQL being 
> constructed?
>

No, I don't think that the sql statement is wrong. I just traying to 
figured out how the sql is generated by Django and why it fails in Firebird.
I found the answere, of course, there is a Firebird limitation on this type 
of statement. Running that query raise a "Data type unknown" error.

https://stackoverflow.com/questions/37348807/data-type-unknown-in-case-expression-with-only-parameters-as-values

I will need to found other strategy to resolve this.

Regards.

 

>
> On Sunday, 15 April 2018 12:25:48 UTC+10, Maximiliano Robaina wrote:
>>
>> Hi,
>>
>> Testing expressions test app, the query generated into 
>> BasicExpressionsTests.test_annotate_values_filter method:
>>
>> companies = Company.objects.annotate(
>> foo=RawSQL('%s', ['value']),
>> ).filter(foo='value').order_by('name')
>>
>> Generate:
>>
>> 'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
>> "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES", "EXPRESSIONS_COMPANY"."NUM_CHAIRS", 
>> "EXPRESSIONS_COMPANY"."CEO_ID", 
>> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
>> "EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY "EXPRESSIONS_COMPANY"."NAME" ASC'
>>
>> This sql command has 3 params (?), two of which are out of where clause.
>>
>> ? AS "FOO" 
>>
>> WHERE ? = ?
>>
>>
>> So, the underlying database driver execute this, doing something like this
>>
>>  cursor.execute(sql, ['value', 'value', 'value'])
>>
>> Is correct that the 3 params are replaced into the entire sql and not 
>> just on where clause ?
>> It depend of the  implementation on each database driver?
>>
>> Best regards
>> Maxi
>>
>>
>>

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Re: django-firebird test expressions

[Josh Smeaton]

It looks correct to me. RawSQL is defining a parameter to be included in 
the query. The RawSQL expression itself is used in the select and on the 
left hand side of the WHERE clause, so the parameter needs to be included 
there. The right hand side of the WHERE clause is a regular string (which 
just happens to also be named "value") which Django will always 
parameterise and has nothing to do with the RawSQL expression itself.

Is there some reason you think there's an issue with the SQL being 
constructed?

On Sunday, 15 April 2018 12:25:48 UTC+10, Maximiliano Robaina wrote:
>
> Hi,
>
> Testing expressions test app, the query generated into 
> BasicExpressionsTests.test_annotate_values_filter method:
>
> companies = Company.objects.annotate(
> foo=RawSQL('%s', ['value']),
> ).filter(foo='value').order_by('name')
>
> Generate:
>
> 'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
> "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES", "EXPRESSIONS_COMPANY"."NUM_CHAIRS", 
> "EXPRESSIONS_COMPANY"."CEO_ID", 
> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
> "EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY "EXPRESSIONS_COMPANY"."NAME" ASC'
>
> This sql command has 3 params (?), two of which are out of where clause.
>
> ? AS "FOO" 
>
> WHERE ? = ?
>
>
> So, the underlying database driver execute this, doing something like this
>
>  cursor.execute(sql, ['value', 'value', 'value'])
>
> Is correct that the 3 params are replaced into the entire sql and not just 
> on where clause ?
> It depend of the  implementation on each database driver?
>
> Best regards
> Maxi
>
>
>

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django-firebird test expressions

[Maximiliano Robaina]

Hi,

Testing expressions test app, the query generated into 
BasicExpressionsTests.test_annotate_values_filter method:

companies = Company.objects.annotate(
foo=RawSQL('%s', ['value']),
).filter(foo='value').order_by('name')

Generate:

'SELECT  "EXPRESSIONS_COMPANY"."ID", "EXPRESSIONS_COMPANY"."NAME", 
"EXPRESSIONS_COMPANY"."NUM_EMPLOYEES", "EXPRESSIONS_COMPANY"."NUM_CHAIRS", 
"EXPRESSIONS_COMPANY"."CEO_ID", 
"EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID", ? AS "FOO" FROM 
"EXPRESSIONS_COMPANY" WHERE ? = ? ORDER BY "EXPRESSIONS_COMPANY"."NAME" ASC'

This sql command has 3 params (?), two of which are out of where clause.

? AS "FOO" 

WHERE ? = ?


So, the underlying database driver execute this, doing something like this

 cursor.execute(sql, ['value', 'value', 'value'])

Is correct that the 3 params are replaced into the entire sql and not just 
on where clause ?
It depend of the  implementation on each database driver?

Best regards
Maxi


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