[Zope] How to identy a fieldname exist or not?

[e-Musty]

ZSQL methods return with a list of records where fields corresponds to the
column names you have defined in the SELECT query. What you have tried to do
is to acces the value of the user_id method, not to determine whether it has
or has not such an attribute.

To workaround the problem staying in the way you started to go on, the
simplest is to embed the last, "filed-existence-investigator" piece of code
in to a try block. If an AttributeError exception is thrown, you can be sure
no user_id attribute exists.

try:
  if result:
    for i in result:
          if i.user_id:
                print "This table have fieldname named user_id"
except (AttributeError):
  print "there's no such a field"

If it would not work, check out the Python/Zope docus to find out the exact
name of the exception to be caught.

By the way, in my opinion you should employ a Python database API to find
out which tables have what fields or to have a ZSQL method submitting a
query on some system tables holding info on another table.

-----Original Message-----
From: zope-admin@zope.org [mailto:zope-admin@zope.org]On Behalf Of Terry
Sent: 2002. január 29. 11:29
To: zope@zope.org
Subject: [Zope] How to identy a fieldname exist or not?


Hello friends,

I have a table1 in database. Have fieldnames like
"book_id","bookname",table2 has  "user_id","username"

I use a Python Script call a ZSQL Method and get result from that ZSQL
Method.
There is not any fieldname like "phone".
Why I couldn't check this in Python Script?
Zope said this on my browser
"""


    Site Error

An error was encountered while publishing this resource.

*Error Type: AttributeError*
*Error Value: user_id*

"""

###My Python Script
result1 =some_ZSQL_Method_table1
result2 =some_ZSQL_Method_table2

result =[]
 for i in range(len(result1)):
         result.append(result1[i])
         if len(result2) >= i+1:
              result.append(result2[i])
 if result:
    for i in result:
          if i.user_id:
                print "This table have fieldname named user_id"

return printed
 #################

Any idea ?

Terry





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