Ed Leafe wrote:
> On Apr 22, 2009, at 4:25 PM, Paul McNett wrote:
>
>> I think what is happening is that I'm constructing the SQL from clause
>> as follows:
>>
>> 111 self.setFromClause("""prod_cust
>> 112 left join product_lines
>> 113 on product_lines.id = prod_cust.prod_id
>> 114 left join customers
>> 115 on customers.id = prod_cust.cust_id""")
>>
>> The new code in setChildFilter() seems to assume (by using split()
>> [-1])
>> that the last word in the from clause is going to be the table alias,
>> but in my case the last 'word' is 'prod_cust.cust_id'.
>>
>> My code above was written prior to dabo having addJoin() and I could
>> certainly rewrite it, but I really don't want to have to if it can be
>> avoided (there are many bizobjs written this way).
>
> OK, there are several approaches to take. One is to forbid implicit
> aliases, and require that from clauses be set with a specific alias
> name. Right now I'm parsing the from clause to get the alias, and non-
> standard from clauses like the one above will not work. The other is
> to require that SQL Builder usage follow certain standards, which your
> setFromClause() clearly violates.
>
> Can you think of any other approach? It would have to handle all of
> the following:
>
> self.setFromClause("prod_cust")
> self.setFromClause("prod_cust pc")
> self.setFromClause("prod_cust as pc")
> self.setFromClause("""prod_cust
> left join product_lines
> on product_lines.id = prod_cust.prod_id
> left join customers
> on customers.id = prod_cust.cust_id""")
> self.setFromClause("""prod_cust pc
> left join product_lines
> on product_lines.id = prod_cust.prod_id
> left join customers
> on customers.id = prod_cust.cust_id""")
> self.setFromClause("""prod_cust as pc
> left join product_lines
> on product_lines.id = prod_cust.prod_id
> left join customers
> on customers.id = prod_cust.cust_id""")
It would also need to handle the joins not being on separate lines like I have
them.
Let's keep the implicitness if we can. BTW I don't consider my from clause
non-standard, because I've always thought of JOIN as a subclause of FROM.
How about something like (untested; looking for comments on the approach only):
def getTableAlias(fromClause):
join_strings = ["left join", "right join", "outer join", "inner join",
"join"]
for join_string in join_strings:
at = fromClause.lower().find(join_string)
if at >= 0:
fromClause = fromClause[:at].strip()
break
return fromClause.strip()[-1]
Paul
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