# Ferret finds 'tests' but not 'test'

**URL:** <https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649>\
**Category:** Ferret\
**Created:** [September 5, 2006, 9:51pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649 "2006-09-05T21:51:52Z")\
**Posts on this page:** 16\
**Page:** 1

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 5, 2006, 9:51pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/1 "2006-09-05T21:51:52Z")

</div>

Hello all,

Quick question (possibly!) - I’ve got a few records indexed and doing a  
search for ‘test’ reports in no hits even though I know the word ‘tests’  
exists in the indexed field. Doing a search for ‘tests’ produces a  
result. I would have thought that ‘test’ would match ‘tests’ but no such  
luck!

Thanks,

Alastair

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 6, 2006, 6:23am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/2 "2006-09-06T06:23:12Z")

</div>

On 9/6/06, Alastair M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Alastair  
> The default analyzer doesn’t perform any stemming. You need to create  
> your own analyzer with a stemmer. Something like this;

```
require 'rubygems'
require 'ferret'

module Ferret::Analysis
  class MyAnalyzer
    def token_stream(field, text)
      StemFilter.new(StandardTokenizer.new(text))
    end
  end
end

index = Ferret::I.new(:analyzer => Ferret::Analysis::MyAnalyzer.new)

index << "test"
index << "tests debate debater debating the for,"
puts index.search("test").total_hits

```

Hope that helps,  
Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 6, 2006, 2:36pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/3 "2006-09-06T14:36:39Z")

</div>

David B. wrote:

> On 9/6/06, Alastair M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > Alastair  
> > The default analyzer doesn’t perform any stemming. You need to create  
> > your own analyzer with a stemmer. Something like this;
> 
> ```
> require 'rubygems'
> require 'ferret'
> 
> module Ferret::Analysis
> class MyAnalyzer
> def token_stream(field, text)
> StemFilter.new(StandardTokenizer.new(text))
> end
> end
> end
> 
> index = Ferret::I.new(:analyzer => Ferret::Analysis::MyAnalyzer.new)
> 
> index << "test"
> index << "tests debate debater debating the for,"
> puts index.search("test").total_hits
> 
> ```
> 
> Hope that helps,  
> Dave

Hi Dave,

Many thanks for the help, it does help! However given the short timespan  
for this project, I think the users of the site will just have to be a  
bit more specific in their search terms 🙂 Cheers and will bookmark your  
reply for a later project.

Alastair

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 29, 2006, 2:37pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/4 "2006-09-29T14:37:04Z")

</div>

Hi there,

Thanks for this useful piece of information! What I’m wondering is how  
do stemming on queries as well. My first try was:

query = Ferret::QueryParser.new(:analyzer =\>  
Ferret::Analysis::StemmingAnalyzer.new).parse(query\_string)

index.search\_each(query) { |doc, score| … }

But this does not work the way I would expect it to work, i.e., it seems  
to deliver empty results independent of the input.

Does anybody have an idea what I’m doing wrong?

Cheers,

Albert

David B. wrote:

> On 9/6/06, Alastair M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > Alastair  
> > The default analyzer doesn’t perform any stemming. You need to create  
> > your own analyzer with a stemmer. Something like this;
> 
> ```
> require 'rubygems'
> require 'ferret'
> 
> module Ferret::Analysis
> class MyAnalyzer
> def token_stream(field, text)
> StemFilter.new(StandardTokenizer.new(text))
> end
> end
> end
> 
> index = Ferret::I.new(:analyzer => Ferret::Analysis::MyAnalyzer.new)
> 
> index << "test"
> index << "tests debate debater debating the for,"
> puts index.search("test").total_hits
> 
> ```
> 
> Hope that helps,  
> Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 29, 2006, 6:21pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/5 "2006-09-29T18:21:12Z")

</div>

On 9/29/06, Albert [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> > ```
> > class MyAnalyzer
> > puts index.search("test").total_hits
> > 
> > ```
> 
> Ferret::Analysis::StemmingAnalyzer.new).parse(query\_string)  
> Albert  
> Hi Albert,

Could you show us your implementation of StemmingAnalyzer as well.  
Also, you need to be sure to use the same analyzer for both indexing  
and analysis, although I think you already new this.

Cheers,  
Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 29, 2006, 6:45pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/6 "2006-09-29T18:45:10Z")

</div>

Hi Dave,

Thanks for following up! The StemmingAnalyzer is actually just the  
MyAnalyzer from the example above:

module Ferret::Analysis  
class StemmingAnalyzer  
def token\_stream(field, text)  
StemFilter.new(StandardTokenizer.new(text))  
end  
end  
end

I’ve been trying to find the error but no success. The searching is  
done this way:

```
i = Ferret::Index::Index.new(:path => index)
qp = Ferret::QueryParser.new(:analyzer => 

```

Ferret::Analysis::StemmingAnalyzer.new)  
query = qp.parse(query\_string)  
i.search\_each(query) { |doc, score| … }

What I don’t get is that search\_each(query) never returns a result  
whereas when I use the original query string as in

```
i = Ferret::Index::Index.new(:path => index)

```

# qp = Ferret::QueryParser.new(:analyzer =\>

Ferret::Analysis::StemmingAnalyzer.new)

# query = qp.parse(query\_string)

```
i.search_each(query_string) { |doc, score| ... }
              ------------

```

things work as expected (modulo the stemmming, of course). So, it may  
be that I fundamentally misunderstand something or make a stupid mistake  
…

Cheers,

Albert

David B. wrote:

> On 9/29/06, Albert [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > > ```
> > > class MyAnalyzer
> > > puts index.search("test").total_hits
> > > 
> > > ```
> > 
> > Ferret::Analysis::StemmingAnalyzer.new).parse(query\_string)  
> > Albert  
> > Hi Albert,
> 
> Could you show us your implementation of StemmingAnalyzer as well.  
> Also, you need to be sure to use the same analyzer for both indexing  
> and analysis, although I think you already new this.
> 
> Cheers,  
> Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 30, 2006, 9:04am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/7 "2006-09-30T09:04:02Z")

</div>

Hi Dave,

Wonderful! Thanks! I should have taken a deeper look at the  
documentation, indeed. Anyway, thanks for your patience!

Cheers,

Al.

David B. wrote:

> On 9/30/06, Albert [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > ```
> > end
> > i.search_each(query) { |doc, score| ... }
> > 
> > ```
> > 
> > things work as expected (modulo the stemmming, of course). So, it may  
> > be that I fundamentally misunderstand something or make a stupid mistake  
> > …
> > 
> > Cheers,
> > 
> > Albert
> 
> Sorry, I must have been tired last night. The problem is obvious to me  
> now. You need to set the :fields parameter. The above query parser  
> should work as long as you explicitly specify all fields in your  
> query. For example:
> 
> ```
> "content:(ruby rails) title:(ruby rails)"
> 
> ```
> 
> But if you want to search all fields by default then you need to tell  
> the QueryParser what fields exist. The Index class will handle all of  
> this for you including using the same analyzer as is used during  
> indexing. It looks like you are using the Index class for your  
> searches so why not just leave the query parsing to it. Otherwise you  
> can get the fields from the reader.
> 
> ```
> query = Ferret::QueryParser.new(
> :analyzer => Ferret::Analysis::StemmingAnalyzer.new,
> :fields => reader.fields,
> :tokenized_fields => reader.tokenized_fields
> ).parse(query_string)
> 
> index.search_each(query) { |doc, score| ... }
> 
> ```
> 
> Hope that helps,  
> Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 30, 2006, 7:25am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/8 "2006-09-30T07:25:49Z")

</div>

On 9/30/06, Albert [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> ```
> end
> i.search_each(query) { |doc, score| ... }
> 
> ```
> 
> things work as expected (modulo the stemmming, of course). So, it may  
> be that I fundamentally misunderstand something or make a stupid mistake  
> …
> 
> Cheers,
> 
> Albert

Sorry, I must have been tired last night. The problem is obvious to me  
now. You need to set the :fields parameter. The above query parser  
should work as long as you explicitly specify all fields in your  
query. For example:

```
"content:(ruby rails) title:(ruby rails)"

```

But if you want to search all fields by default then you need to tell  
the QueryParser what fields exist. The Index class will handle all of  
this for you including using the same analyzer as is used during  
indexing. It looks like you are using the Index class for your  
searches so why not just leave the query parsing to it. Otherwise you  
can get the fields from the reader.

```
query = Ferret::QueryParser.new(
    :analyzer => Ferret::Analysis::StemmingAnalyzer.new,
    :fields => reader.fields,
    :tokenized_fields => reader.tokenized_fields
).parse(query_string)

index.search_each(query) { |doc, score| ... }

```

Hope that helps,  
Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [October 9, 2006, 11:19am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/9 "2006-10-09T11:19:20Z")

</div>

Hi, if I use this stemming analyzer, where do I put it ? /lib/ and  
require it in each model?

-Anrake

David B. wrote:

> On 9/6/06, Alastair M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > Alastair  
> > The default analyzer doesn’t perform any stemming. You need to create  
> > your own analyzer with a stemmer. Something like this;
> 
> ```
> require 'rubygems'
> require 'ferret'
> 
> module Ferret::Analysis
> class MyAnalyzer
> def token_stream(field, text)
> StemFilter.new(StandardTokenizer.new(text))
> end
> end
> end
> 
> index = Ferret::I.new(:analyzer => Ferret::Analysis::MyAnalyzer.new)
> 
> index << "test"
> index << "tests debate debater debating the for,"
> puts index.search("test").total_hits
> 
> ```
> 
> Hope that helps,  
> Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [September 30, 2006, 10:50am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/10 "2006-09-30T10:50:08Z")

</div>

Alastair M. wrote:

> Hello all,
> 
> Quick question (possibly!) - I’ve got a few records indexed and doing a  
> search for ‘test’ reports in no hits even though I know the word ‘tests’  
> exists in the indexed field. Doing a search for ‘tests’ produces a  
> result. I would have thought that ‘test’ would match ‘tests’ but no such  
> luck!
> 
> Thanks,
> 
> Alastair

Alastair - if you only want to find the plural of something and not the  
full stem of words then ROR has a plurisation capability. It will take  
test and bring back all the plurals or take tests and bring back the  
singulars. You can then search on all these words. It is not a full  
stemmer but in some circumstances perhaps this may be all that you are  
wanting to do.

One thing to watch that caught us out was that as standard  
pluralistation of words with two ‘ss’ at the end does not work properly.  
For example, “glass” would come back as “glas” from the pluralizer.  
There is a simple fix that is in the ROR forum that covers all this off.

I would only use the ror pluraliser if all you are looking to do is  
bring back plurals of words and are not interested in the full stemming  
of the words. For example, if you do a search on “tax” full stemming  
should also search on “taxes” and “taxation”. Pluralise would not search  
on “taxation”.

Hope this helps.

Clare

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [October 27, 2006, 12:05am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/11 "2006-10-27T00:05:03Z")

</div>

On 26.10.2006, at 22:06, Ghost wrote:

> Can someone give me an idiots guide as to how to implement this custom  
> stemming analyser. I do not know where to start.

1. Create the analyzer as David outlined it and name the file  
“my\_analyzer.rb”. If you put it in /app/models you don’t need any  
require statements since every .rb file in /app/models gets  
automagically ‘required’ by Rails.

> end  
> end

1. When you create an Index instance, pass it your analyzer, like so:

index = Ferret::I.new(:analyzer =\> Ferret::Analysis::MyAnalyzer.new)

1. Test your analyzer, e.g.

index \<\< “walking”  
index \<\< “walked”  
index \<\< “walks”

index.search(“walk”).total\_hits # -\> 3

> Thanks for your patience.

You’re welcome. And may I kindly ask you to use a valid email address  
and perhaps your real name for future posts?

Kind regards,  
Andreas

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [October 26, 2006, 10:06pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/12 "2006-10-26T22:06:55Z")

</div>

anrake wrote:

> Hi, if I use this stemming analyzer, where do I put it ? /lib/ and  
> require it in each model?
> 
> -Anrake
> 
> David B. wrote:
> 
> > On 9/6/06, Alastair M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:  
> > Can someone give

Can someone give me an idiots guide as to how to implement this custom  
stemming analyser. I do not know where to start.

Thanks for your patience.

> > > Alastair  
> > > The default analyzer doesn’t perform any stemming. You need to create  
> > > your own analyzer with a stemmer. Something like this;
> > 
> > ```
> > require 'rubygems'
> > require 'ferret'
> > 
> > module Ferret::Analysis
> > class MyAnalyzer
> > def token_stream(field, text)
> > StemFilter.new(StandardTokenizer.new(text))
> > end
> > end
> > end
> > 
> > index = Ferret::I.new(:analyzer => Ferret::Analysis::MyAnalyzer.new)
> > 
> > index << "test"
> > index << "tests debate debater debating the for,"
> > puts index.search("test").total_hits
> > 
> > ```
> > 
> > Hope that helps,  
> > Dave

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [October 27, 2006, 11:58am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/13 "2006-10-27T11:58:34Z")

</div>

Hi I’m still having trouble with this. Probably something stupid but  
here goes.

I’m using ferret version 0.13 and aaf.

I created this file in my app/models directory

require ‘ferret’  
include Ferret

module Ferret::Analysis  
class MyAnalyzer  
def token\_stream(field, text)  
StemFilter.new(StandardTokenizer.new(text))  
end  
end  
end

naming it my\_analyzer.rb as directed.

and then in my ferret model i have the following declarion.

acts\_as\_ferret :fields=\> [‘short\_description’],:analyzer =\>  
Ferret::Analysis::MyAnalyzer.new

I tried to rebuild my index but it crashes out with the following error:

> > VoObject.rebuild\_index  
> > NameError: uninitialized constant MyAnalyzer  
> > from  
> > /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active\_support/dependencies.rb:123:in  
> > `const_missing' from script/../config/../config/../app/models/vo_object.rb:14 from /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:140:in`load’  
> > from  
> > /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active\_support/dependencies.rb:56:in  
> > `require_or_load' from /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:30:in`depend\_on’  
> > from  
> > /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active\_support/dependencies.rb:85:in  
> > `require_dependency' from /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:98:in`const\_missing’  
> > from  
> > /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active\_support/dependencies.rb:131:in  
> > `const\_missing’  
> > from (irb):11
> 
> >

Nasty eh?

Any idea what is going on here? Why can’t my VoObject model see the new  
analyzer?  
Thanks again.

> You’re welcome. And may I kindly ask you to use a valid email address  
> and perhaps your real name for future posts?

I used to post with a valid email address. But then the number of spam  
messages i recieved went from 1 or 2 a week to 50-60 a day. Ruby Forum  
used to print the email addresses on the page. Heres a comprimise.

Regards  
Caspar

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [March 5, 2007, 5:13am UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/14 "2007-03-05T05:13:24Z")

</div>

Andreas K. wrote:

> Hi Caspar,
> 
> On 27.10.2006, at 11:58, Ghost wrote:
> 
> > NameError: uninitialized constant MyAnalyzer  
> > Sorry, I forgot to mention that the directory structure needs to  
> > resemble the module nesting, i.e. the file must go in app/models/  
> > ferret/analysis instead of just app/models.
> 
> Cheers,  
> Andy

I’ve been trying to use the solution for stemming discussed in this  
thread and have run into a bit of trouble.

I’m using this analyzer:

module Ferret::Analysis  
class StemmingAnalyzer  
def token\_stream(field, text)  
StemFilter.new(StandardTokenizer.new(text))  
end  
end  
end

I’ve configured aaf thusly:

AAF\_DEFAULT\_FERRET\_OPTIONS = {:analyzer =\>  
Ferret::Analysis::StemmingAnalyzer.new}

acts\_as\_ferret({:store\_class\_name =\> true,  
:fields =\> {:description =\> {:store =\>  
:yes}}}.merge(AAF\_DEFAULT\_OPTIONS),  
AAF\_DEFAULT\_FERRET\_OPTIONS)

The first time I search for something a new index is created in index,  
and it successfully returns a set of results. The second time I search,  
however, I get a strange error:

uninitialized constant Ferret::Search

#{RAILS\_ROOT}/vendor/rails/activesupport/lib/active\_support/dependencies.rb:264:in  
`load_missing_constant' #{RAILS_ROOT}/vendor/rails/activesupport/lib/active_support/dependencies.rb:453:in`const\_missing’  
#{RAILS\_ROOT}/vendor/plugins/acts\_as\_ferret/lib/local\_index.rb:160:in  
`query_for_record' #{RAILS_ROOT}/vendor/plugins/acts_as_ferret/lib/local_index.rb:152:in`document\_number’  
#{RAILS\_ROOT}/vendor/plugins/acts\_as\_ferret/lib/local\_index.rb:135:in  
`highlight' /opt/local/lib/ruby/1.8/monitor.rb:238:in`synchronize’  
#{RAILS\_ROOT}/vendor/plugins/acts\_as\_ferret/lib/local\_index.rb:134:in  
`highlight' #{RAILS_ROOT}/vendor/plugins/acts_as_ferret/lib/instance_methods.rb:30:in`highlight’

Perhaps it has something to do with loading an already created index?

Thanks,  
-Adam

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [April 9, 2009, 4:34pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/15 "2009-04-09T16:34:31Z")

</div>

This is just postscript correction for this thread, in case anyone else  
browses to it (like i did) and gets sent down the slightly wrong track.

If you’re going to include the :analyzer option in your call to  
acts\_as\_ferret, then it needs to live inside another option hash called  
:ferret. EG, some of the examples above say to do this:

acts\_as\_ferret :fields=\> [‘short\_description’],  
:analyzer =\> Ferret::Analysis::MyAnalyzer.new

This won’t work - it needs to be like this:

acts\_as\_ferret :fields=\> [‘short\_description’],  
:ferret =\> {:analyzer =\>  
Ferret::Analysis::MyAnalyzer.new}

Thanks to Jens for setting me straight on this 🙂

---

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**Author:** ![welly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f0a364/32.png) [@welly](https://www.ruby-forum.com/u/welly)\
**Post date:** [October 27, 2006, 3:53pm UTC](https://www.ruby-forum.com/t/ferret-finds-tests-but-not-test/67649/16 "2006-10-27T15:53:41Z")

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Hi Caspar,

On 27.10.2006, at 11:58, Ghost wrote:

> NameError: uninitialized constant MyAnalyzer  
> Sorry, I forgot to mention that the directory structure needs to  
> resemble the module nesting, i.e. the file must go in app/models/  
> ferret/analysis instead of just app/models.

Cheers,  
Andy