# Need clarification of documentation

**URL:** <https://www.ruby-forum.com/t/need-clarification-of-documentation/87627>\
**Category:** Ferret\
**Created:** [March 4, 2007, 4:51pm UTC](https://www.ruby-forum.com/t/need-clarification-of-documentation/87627 "2007-03-04T16:51:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![builderchad](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/9e8a1a/32.png) [@builderchad](https://www.ruby-forum.com/u/builderchad)\
**Post date:** [March 4, 2007, 4:51pm UTC](https://www.ruby-forum.com/t/need-clarification-of-documentation/87627/1 "2007-03-04T16:51:51Z")

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Hi, I have question about the delete() method docs.

I am re-indexing data on the fly so I would like to delete any existing  
indexed data for a particular resource before re-indexing it using  
index.delete(id).

The delete() method api doc says:

"Delete the document referenced by the document number id if id is an  
integer or all of the documents which have the term id if id is a term…

id: The number of the document to delete"

I am a little confused by what this means. At the time of deletion all  
I have is my own ID of the resource which was previously indexed in  
ferret with my own field :id. If I supply my own ID will the correct  
indexed data be deleted? Or does this ID refer to ferrets own internal  
ID for the resource?

One other question while I am on the subject - will deleting a resource  
that does not exist raise an error. I ask this because I would like to  
index new data structures that haven’t been indexed before and would  
like to avoid checking in the index first whether or not it exists  
before attempting to delete.

Thanks,

Chad.

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**Author:** ![builderchad](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/9e8a1a/32.png) [@builderchad](https://www.ruby-forum.com/u/builderchad)\
**Post date:** [March 6, 2007, 4:11am UTC](https://www.ruby-forum.com/t/need-clarification-of-documentation/87627/2 "2007-03-06T04:11:35Z")

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On 3/5/07, Chad T. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> integer or all of the documents which have the term id if id is a term…
> 
> id: The number of the document to delete"
> 
> I am a little confused by what this means.

Is this any clearer?

```
# Deletes a document/documents from the index. The method for 

```

determining  
# the document to delete depends on the type of the argument passed.  
#  
# If +arg+ is an Integer then delete the document based on the  
internal  
# document number.  
#  
# If +arg+ is a String then search for the documents with +arg+ in  
the  
# +id+ field. The +id+ field is either :id or whatever you set the  
:id\_field  
# parameter to when you create the Index object.

> At the time of deletion all  
> I have is my own ID of the resource which was previously indexed in  
> ferret with my own field :id. If I supply my own ID will the correct  
> indexed data be deleted? Or does this ID refer to ferrets own internal  
> ID for the resource?

In this case, since your id is probably an integer you will need to  
convert it to a string or Ferret will delete the documents by internal  
document number rather than your own ID for the resource.

> One other question while I am on the subject - will deleting a resource  
> that does not exist raise an error. I ask this because I would like to  
> index new data structures that haven’t been indexed before and would  
> like to avoid checking in the index first whether or not it exists  
> before attempting to delete.

Yes, if you delete by internal document number. No, if you are  
deleting by term, ie passing your own document id which is stored in  
the _id_ field. So in your case you should be fine. I should also  
mention that you can set the :key parameter to :id;

```
index = Ferret::Index::Index.new(:key => :id)

```

This way, whenever you add a document with an id that already exists  
in the index it will replace the existing document.

For example;

```
require 'rubygems'
require 'ferret'

index = Ferret::I.new(:key => :id)

[
  {:id => '1', :text => 'one'},
  {:id => '2', :text => 'Two'},
  {:id => '3', :text => 'Three'},
  {:id => '1', :text => 'One'}
].each {|doc| index << doc}

puts index.size # => 3
puts index['1'].load.inspect # => {:text=>"One", :id=>"1"}
puts index.search('id:1').to_s(:text)
    # => TopDocs: total_hits = 1, max_score = 1.287682 [
    # 3 "One": 1.287682
    # ]

```

Hope that helps,  
Dave

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<div class="post-metadata">

**Author:** ![builderchad](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/9e8a1a/32.png) [@builderchad](https://www.ruby-forum.com/u/builderchad)\
**Post date:** [March 6, 2007, 3:31pm UTC](https://www.ruby-forum.com/t/need-clarification-of-documentation/87627/3 "2007-03-06T15:31:32Z")

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Thanks Dave, that has cleared everything up for me. Excellent engine by  
the way, thanks for all your hard work on this.