Python 3 Index out of range error

Question

I have the following piece of code executing in a postgresql server.

from datetime import datetime

now = str(datetime.now(None))
procurementinsertqueries=[]
priceupdatequeries = []
inventoryupdatequeries=[]
ptrcode = -1
debugcode=""

try:
    unpbatches=[]
    query = "select distinct(fk_procurementbatch_code) from newprocurementlist"
    proclistresult = plpy.execute(query)

    for rec in proclistresult:
        unpbatches.append(rec["fk_procurementbatch_code"])

    for batchcode in unpbatches:
        ptrcode=-1
        query = "select procurementtransaction_code from procurement where fk_procurementbatch_code="+str(batchcode)+" order by procurementtransaction_code desc limit 1"
        ptrcoderesult = plpy.execute(query)

        if len(ptrcoderesult)==0:
            ptrcode=0
        else:
            ptrcode=ptrcoderesult[0]["procurementtransaction_code"]

        query = "select * from newprocurementlist where fk_procurementbatch_code="+str(batchcode)
        newproclistresult = plpy.execute(query)

        for r in newproclistresult: 
            ptrcode+=1
            _bcode = str(r["fk_procurementbatch_code"])
            _pref = str(r["fk_product_ref"])
            _up = str(r["unitsprocured"])
            _tp = str(r["totalprice"])
            _cp = str(r["costprice"])
            _sp = str(r["sellingprice"])
            _mrp = str(r["mrp"])
            _trcode = str(ptrcode)
            procurementinsertqueries.append("insert into procurement values("+_bcode+","+_pref+","+_up+","+_tp+","+_cp+","+_sp+","+_mrp+","+_trcode+")")
            priceupdatequeries.append("insert into productpriceupdatelist values("+_pref+")")
            _aunits = 0.0
            _newunits = 0.0
            query="select unitsavailable from inventory where fk_product_ref="+_pref
            au = -1
            au = plpy.execute(query)
            _aunits=float(au[0]["unitsavailable"])
            _newunits = _aunits+float(r["unitsprocured"])
            inventoryupdatequeries.append("update inventory set unitsavailable="+str(_newunits)+" where fk_product_ref="+_pref)
            debugcode+="--Completed--"
        debugcode+="---Loop completed---"   

except Exception as e:
    plpy.execute("insert into log values(\'"+now+"\')")
    raise plpy.error("Error generating insert queries-->"+str(e)+"Debug is "+debugcode)

try:
    with plpy.subtransaction():
        for qry in procurementinsertqueries:
            plpy.execute(qry)
        for qry in priceupdatequeries:
            plpy.execute(qry)   
        for qry in inventoryupdatequeries:
            plpy.execute(qry)
except Exception as e:
    plpy.execute("insert into log values(\'"+now+": Error executing insert queries\')")
    raise plpy.error("Error executing procurement updates. There could be loss of data.Please review database error log. -->"+str(e))

try:
    plpy.execute("delete from newprocurementlist")
except Exception as e:
    plpy.execute("insert into log values(\'"+now+": Error deleting new procurement list table after successful updates\')")
    raise plpy.error("Error deleting completed procurement list. There could be duplication of data. Review error log file-->"+str(e))

try:
    plpy.execute("select product_price_update_process()")
except Exception as e:
    raise plpy.error("Error updating prices. "+str(e))

The problem is that I am getting an "index out of range" error. Attached is the erro I am getting.

ERROR:  plpy.Error: Error generating insert queries-->list index out of rangeDebug is --Completed--
CONTEXT:  Traceback (most recent call last):
  PL/Python function "procurementlist_process", line 61, in <module>
    raise plpy.error("Error generating insert queries-->"+str(e)+"Debug is "+debugcode)
PL/Python function "procurementlist_process"

I am not able to understand how the index is out of range when I am using a for loop.

Please help !!

EDIT : Note that the test data in my table, the number of items in unpbatches is only 1.

You're swallowing the original exception. For testing purposes, reraise it in your except statement so we can see which lne it's actually coming from. — jeffknupp
– jeffknupp, Commented Feb 22, 2013 at 13:52
The exception is coming at the point where I am updating the queries lists. The control is not even going to the part where the queries are being executed. The error is popping up where I am inserting the queries to the appropriate lists. — Raghavendra Kumar
– Raghavendra Kumar, Commented Feb 22, 2013 at 13:54
You really need to just call raise by itself in the except clause so we can see the actual traceback and line numbers. — jeffknupp
– jeffknupp, Commented Feb 22, 2013 at 14:16
When I use "raise plpy.error(e)" i get this.-->ERROR: plpy.Error: list index out of range CONTEXT: Traceback (most recent call last): PL/Python function "procurementlist_process", line 64, in <module> raise plpy.error(e) PL/Python function "procurementlist_process" — Raghavendra Kumar
– Raghavendra Kumar, Commented Feb 22, 2013 at 14:24

Janne Karila · Accepted Answer · 2013-02-22 20:49:37Z

1

Perhaps au is an empty list here:

    au = plpy.execute(query)
    _aunits=float(au[0]["unitsavailable"])

Is au the result set of the query? Maybe the query did not return any rows.

More generally speaking, you should follow jknupp's suggestion in the comments and change

raise plpy.error("Error generating insert queries-->"+str(e)+"Debug is "+debugcode)

to just

raise

to see the original traceback and the exact line where the error occurred.

edited Feb 22, 2013 at 20:49

answered Feb 22, 2013 at 13:52

Janne Karila

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2 Comments

Raghavendra Kumar Over a year ago

Checked it. Here is the error with a trace of _aunits. --plpy.Error: Error generating insert queries-->list index out of rangeDebug is _aunits = :1300.0--Completed----

Raghavendra Kumar Over a year ago

The code is completing till the first iteration of the main for loop. Note that the number of batchcodes is only 1 in my test data. Does it make any difference??

jeffknupp · Accepted Answer · 2013-02-22 14:06:31Z

1

You're setting ptrcode to 1 if its length is 0, then immediately updating it when you enter the loop. Perhaps you meant to set it to 0?

answered Feb 22, 2013 at 14:06

jeffknupp

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1 Comment

Raghavendra Kumar Over a year ago

Yes. Thank you. That is a mistake on my part. However, the ptrcode is just a column in a table and I've checked it with 0 as well, the error persists. It's value is not the cause of the error.

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