Question about string compares with ruby

rubyonrails-talk
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

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

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

5

try this:

`term = params[:term].split.first

unless term.empty?

match = "%#{term}%"

@return= Return.find(:all, :conditions=>['(fieldName like

?)',term])

end`

LAB wrote: