Asp Forum - newbie file write problem

Lars Zeb

1/29/2008 8:58:00 PM

This is my first attempt at ruby. I've written a class (SicCode) which
parses a line and outputs a SQL command.

I use the following to read an input file and to attempt to write:

f = File.new("text.txt", "w")
File.open("small.txt").each {
|line|
s = SicCode.new(line).get_sql
f.puts "#{s}"
}
f.puts "This is a string"
f.close

The output file contains a blank line for each input line, plus the
"This is a string" line. If I change the put to f.puts s, I get a nil
for each input line. The get_sql method works fine interactively when
I pass the class a string.

What am I doing wrong?

Frustrated

14 Answers

7stud --

1/29/2008 9:24:00 PM

Lars Zeb wrote:
> This is my first attempt at ruby. I've written a class (SicCode) which
> parses a line and outputs a SQL command.
>
> I use the following to read an input file and to attempt to write:
>
> f = File.new("text.txt", "w")
> File.open("small.txt").each {
> |line|
> s = SicCode.new(line).get_sql

It sounds like your last line is the problem, so it doesn't have
anything to do with writing to a file. You are having trouble
retrieving the value for s.

--
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yermej

1/29/2008 9:33:00 PM

On Jan 29, 2:57 pm, Lars Zeb <lar...@gmail.com> wrote:
> f = File.new("text.txt", "w")
> File.open("small.txt").each {
> |line|
> s = SicCode.new(line).get_sql
> f.puts "#{s}"
> }
> f.puts "This is a string"
> f.close
>
> The get_sql method works fine interactively when
> I pass the class a string.

If get_sql works in irb, it could be that the line endings in the file
are throwing it off. Try using:

SicCode.new(line.chomp).get_sql

and see if that works.

Lars Zeb

1/29/2008 9:58:00 PM

If I change to:

f = File.new("d:\downloads\\text.txt", "w")
File.open("D:\downloads\\SIC-small.txt").each {
|line|
s = SicCode.new(line.chomp).get_sql
f.puts s
}
f.puts "This is a string"
f.close

Each input line is written as nil to the output file. And I do see the
output I expect on the console.

If I change the script to:

File.open("D:\downloads\\SIC-small.txt").each {
|line|
s = SicCode.new(line).get_sql
puts s
}

I see the expected output to the console as well. If it matters, here
is the output for two lines:
IF EXISTS (SELECT * FROM Sic WHERE Code = '3291')
BEGIN
UPDATE Sic
SET Descr = 'ABRASIVE PRODUCTS'
WHERE Code = '3291'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '3291', 'ABRASIVE PRODUCTS', getdate()
END
nil

IF EXISTS (SELECT * FROM Sic WHERE Code = '6321')
BEGIN
UPDATE Sic
SET Descr = 'ACCIDENT AND HEALTH INSURANCE'
WHERE Code = '6321'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '6321', 'ACCIDENT AND HEALTH INSURANCE', getdate()
END

nil

7stud --

1/29/2008 11:38:00 PM

Lars Zeb wrote:
> Each input line is written as nil to the output file. And I do see the
> output I expect on the console.
>

Hi,

It's time to stop asking us to debug imaginary code. Post a simple,
complete working example that is less than 20 lines and demonstrates
your problem.
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Lars Zeb

1/30/2008 12:17:00 AM

Sorry, I can't do it in 20 lines, but it's very simple.

The class:
class SicCode
def initialize(line)
split_to_columns(line)
end

def split_to_columns(line)
a = line.split(/\s+/)
@sic = a[0]
@descr = a.last(a.length - 1 ).join(" ")
end

def get_sic
@sic
end

def get_descr
@descr
end

def get_sql
puts %Q{IF EXISTS (SELECT * FROM Sic WHERE Code = '#@sic')
BEGIN
UPDATE Sic
SET Descr = '#@descr'
WHERE Code = '#@sic'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '#@sic', '#@descr', getdate()
END
}
end
end

Input file(small.txt):
3291 ABRASIVE PRODUCTS
6321 ACCIDENT AND HEALTH INSURANCE
8720 ACCOUNTING, AUDITING, & BOOKKEEPING

Run this script:
irb(main):175:0> f = File.new("text.txt", "w")
=> #<File:d:downloads\text.txt>
irb(main):176:0> File.open("small.txt").each {
irb(main):177:1* |line|
irb(main):178:1* s = SicCode.new(line).get_sql
irb(main):179:1> f.puts s
irb(main):180:1> }
IF EXISTS (SELECT * FROM Sic WHERE Code = '3291')
BEGIN
UPDATE Sic
SET Descr = 'ABRASIVE PRODUCTS'
WHERE Code = '3291'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '3291', 'ABRASIVE PRODUCTS', getdate()
END

IF EXISTS (SELECT * FROM Sic WHERE Code = '6321')
BEGIN
UPDATE Sic
SET Descr = 'ACCIDENT AND HEALTH INSURANCE'
WHERE Code = '6321'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '6321', 'ACCIDENT AND HEALTH INSURANCE', getdate()
END

IF EXISTS (SELECT * FROM Sic WHERE Code = '8720')
BEGIN
UPDATE Sic
SET Descr = 'ACCOUNTING, AUDITING, & BOOKKEEPING'
WHERE Code = '8720'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '8720', 'ACCOUNTING, AUDITING, & BOOKKEEPING',
getdate()
END

Output file, text.txt, is empty (0 bytes).

7stud --

1/30/2008 5:01:00 AM

Lars Zeb wrote:
> def get_sql
> puts %Q{IF EXISTS (SELECT * FROM Sic WHERE Code = '#@sic')
> BEGIN
> UPDATE Sic
> SET Descr = '#@descr'
> WHERE Code = '#@sic'
> END
> ELSE
> BEGIN
> INSERT INTO Sic
> SELECT '#@sic', '#@descr', getdate()
> END
> }
> end

> irb(main):178:1* s = SicCode.new(line).get_sql
irb(main):179:1> f.puts s

What is s? s is assigned the return value of get_sql(). What's the
return value of get_sql?
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Lars Zeb

1/30/2008 5:10:00 AM

I expected it was something like the following for each input line:
IF EXISTS (SELECT * FROM Sic WHERE Code = '3291')
BEGIN
UPDATE Sic
SET Descr = 'ABRASIVE PRODUCTS'
WHERE Code = '3291'
END
ELSE
BEGIN
INSERT INTO Sic
SELECT '3291', 'ABRASIVE PRODUCTS', getdate()
END

7stud --

1/30/2008 5:23:00 AM

Lars Zeb wrote:
> I expected it was something like the following for each input line:
> IF EXISTS (SELECT * FROM Sic WHERE Code = '3291')
> BEGIN
> UPDATE Sic
> SET Descr = 'ABRASIVE PRODUCTS'
> WHERE Code = '3291'
> END
> ELSE
> BEGIN
> INSERT INTO Sic
> SELECT '3291', 'ABRASIVE PRODUCTS', getdate()
> END

Is there no way to test what the return value of a function is? What's
the return value of the following function:

def sayhi
puts "hello"
end

--
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7stud --

1/30/2008 5:43:00 AM

Concepts you need to explore:

1) What's the return value of the following method:

def g
return 10
end

Can you write some code that proves what the return value is?

2) What's the return value of the following method:

def g
20
end

Can you write some code that proves what the return value is?

2) What's the return value of g():

def f
return 10
end

def g
return f
end

3) What's the return value of g():

def f
return 10
end

def g
f
end

--
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Morton Goldberg

1/30/2008 1:13:00 PM

On Jan 29, 2008, at 7:20 PM, Lars Zeb wrote:

> def get_sql
> puts %Q{IF EXISTS (SELECT * FROM Sic WHERE Code = '#@sic')
> BEGIN
> UPDATE Sic
> SET Descr = '#@descr'
> WHERE Code = '#@sic'
> END
> ELSE
> BEGIN
> INSERT INTO Sic
> SELECT '#@sic', '#@descr', getdate()
> END
> }
> end

Your problem has a simple fix -- remove the 'puts'. You want the
string returned -- puts writes the string to stdout and returns nil.

Regards, Morton

comp.lang.ruby

newbie file write problem

Lars Zeb

7stud --

yermej

Lars Zeb

7stud --

Lars Zeb

7stud --

Lars Zeb

7stud --

7stud --

Morton Goldberg

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