Question about string compares with ruby

Rails
1

Say I have two entries in my database:

  1. Bartlett
  2. Peabody

A user runs a search, and I want to return all matches to the name
above. So the user types in “Bartlett Street”, and I want it to
return #1 above. My ruby code looks like:

@term = params[:terms]
@return = Return.find(:all, :conditions=>[’(fieldName <= ?)’, @term])

Note that because the user types in “Street” at the end, I can not do
a explicit “==” comparison.

When I type in “Peabody” as the search term, why does it also return
“Bartlett”. I understand that “B” comes before “P” in the alphabet,
but I would expect the “<=” to compare on each character in the
string, not just the first … but it seems like it only checks the
first character?

I guess it is more of a SQL syntax question, but does anyone have a
better way to code this in ruby? Seems like such a simple thing to be
able to do.

Thanks in advance!
LAB

2

On 2 Oct 2007, at 00:55, LAB wrote:

When I type in “Peabody” as the search term, why does it also return
“Bartlett”. I understand that “B” comes before “P” in the alphabet,
but I would expect the “<=” to compare on each character in the
string, not just the first … but it seems like it only checks the
first character?

That’s a fairly standard lexicographic ordering: starting from the
first character, compare pairs of characters until you find a pair
that differ (or until you run out of pairs)

I guess it is more of a SQL syntax question, but does anyone have a
better way to code this in ruby? Seems like such a simple thing to be
able to do.

Correct. You want to use the % sql wildcard, ie “where name like
‘Barlett%’”

Fred

3

Hi LAB,

LAB wrote:

I guess it is more of a SQL syntax question, but does anyone have a
better way to code this in ruby? Seems like such a simple thing to be
able to do.

Not tested, but expect you should experiment with LIKE… Probably end
up
with something like…

Return.find(:all, :conditions => 'fieldName LIKE %Q{@term}%)

HTH,
Bill

4

try this:

term = params[:term].split.first
unless term.empty?
match = “%#{term}%”
@return= Return.find(:all, :conditions=>[’(fieldName like ?)’,term])
end

5

Thanks for those suggestions!! Inspired by those, I came up with a
new solution …

In my case @term is always going to be longer than fieldName, so I
would need to search for the wildcard as part of the fieldName, and
not the @term. Instead, I decided that what I really need to do, is
shorten @term. So if @term = “Bartlett Street”, I really only want to
match against the first string there … “Bartlett” and lose the
“Street” part of the @term.

Here’s what I did:

@term = params[:terms] //“Bartlett Street”
@termArray = @term.split // [“Bartlett”, “Street”]
@match = @termArray.first // "Bartlett

if (!@match.nil?)
@return= Return.find(:all, :conditions=>[’(fieldName like ?)’,
@match])
end

That seems to get me what I want … but it is a pretty unique case.
I’m sure using the wildcard would provide a more general solution, but
I wasn’t sure how to apply the wildcard to the “fieldName” in the SQL
statement … I just kept getting syntax errors. This will work fine
for me now.

Thanks again for all the feedback!

LAB