advanced act_as_solr

原文出处：http://www.quarkruby.com/2007/9/14/advanced-acts_as_solr

This article extends our acts_as_solr : search and faceting tutorial and talks about how to manage rails associations, solr indexes and more with acts_as_solr.

Table Of Contents

1. Rebuild Solr index
2. Import existing Solr index or your custom Solr schema.xml
3. Highlight search term
4. Rails associations and acts_as_solr
5. Tips

Rebuild Solr Index

rebuild_solr_index is a class method to re-build your model indexes on import of external data.

For large tables rebuilding Solr index is a time consuming process. See the fifth line in the pseudo code below (index optimization call), it makes rebuild_solr_index a slow process. For large tables, you do not want optimization to take place for each object added to the table. Whereas, removing optimization calls slows down the process of updating solr index.

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## pseudo code def rebuild_solr_index for_each_row_in_table do |doc| doc.save_to_solr_index index.optimize end end

The solution to the problem is to use batch_size in #rebuild_solr_index. With batch size, say for example 100, the index optimization call is executed after indexing 100 rows.

If you do not want to index the complete data but only few rows based on conditions, use optional arguments batch_size and finder in rebuild_solr_index.

• batch_size : to optimize index after adding batch_size items. Default value is 1.
• finder : it is used for conditional indexation. It takes a method as argument which returns objects to be indexed. Default method is :

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  def finder(ar, options) ar.find (:all, options.merge({:order => self.primary_key})) end

Import existing Solr index or your custom Solr schema.xml

Assumption: Column names in table definition are same as the names of the fields using which index has been/will be created.

• Add your indexed fields to vendor/plugins/acts_as_solr/solr/solr/conf/schema.xml (continuing with example of our previous tutorial, we add name1, brand, resolution to schema.xml).
  Remember, to copy them to text field using solr's copyfield directive. text is the default field/column in which search is made, so using copyField we add all data to default search field. The new schema.xml looks like...

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  <field name="text" type="text" indexed="true" stored="true" multiValued="true"/> <field name="name1" type="text" indexed="true" stored="false" /> <field name="brand" type="string" indexed="true" stored="false" /> <field name="resolution" type="sfloat" indexed="true" stored="false" /> <copyField source="*_facet" dest="text"/> <copyField source="brand" dest="text"/> <copyField source="name1" dest="text"/>

• Apply our patch (download). For indexing and searching, acts_as_solr suffixes dataType (e.g. int, float, string etc) of column to the column name, this patch tells acts_as_solr not to do this since we have explicitly created entries for these columns in schema file:

  1 2	cd /path/to/rails/dir patch -p0 custom-schema.patch

• Modify your acts_as_solr definition:

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  class Camera acts_as_solr :custom_schema=>true, :fields=>[:name,:brand,:resolution] end

• ... and it works!

 

Highlight search terms

Goal is to highlight search term(s) in search results. Follow the steps below :

• Modify solrConfig.xml to enable highlighting. Apply our patch (download) as:

  1 2	cd /path/to/rails/dir patch -p0 highlight-solrconfig.patch

• acts_as_solr does not stores any of the field values as it is in its index. We need to modify the configuration file vendor/plugins/acts_as_solr/solr/solr/conf/schema.xml to enable storage of data, which is required to return the highlighted text data. For example, we modify configuration file to store the fields having text dataType to get highlighted matching terms for name1 field.

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  <!-- Original config --> <dynamicField name="*_t" type="text" indexed="true" stored="false"/> <!-- New config --> <dynamicField name="*_t" type="text" indexed="true" stored="true"/>

• Apply one more patch in the same way as the previous one. This patch enables acts_as_solr to handle the option of highlighting in find_by_solr queries and parses the results returned by solr. And now we are ready to roar...

• Lets see it in action with an example

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  @results = Camera.find_by_solr("canon powershot", :highlight=>{:fields=>"name1"}) @results.highlights ## returns hash of objects id and hash of the columns with matched text data {1=>{:name1=>"<em>Canon</em> <em>Powershot</em> sd1000"} ... } #You want to display names with highlighted terms: @results.docs.each do |doc| <%= @results.highlights[doc.id][:name1] -%><br/> end

• Options for highlighting (You can also refer them here)
  
  1. fields: columns to highlight terms for (default is none, and no highlighted text)
  2. prefix: You do not want to have "<em>" tag around matched search term(s), tell your tag here. (eg. "<span class='highlight'>")
  3. suffix: Ending tag for matched term(s)
  4. max_snippets: stop searching the column after max_snippets matched terms found
  Currenlty acts_as_solr does not implements these options at each column level, so you cannot ask to apply some of the options to only one (or few) columns. For e.g. you cannot ask acts_as_solr to use <em> tags for one field and <span class='highlight'> for other field.

 

Note: If you want both the functionalities Custom schema and Highlighting together, use these two patches. Patch 1 and Patch 2.

Rails associations and acts_as_solr

Lets say I have two models, User (columns: username, password) and UserProfile (columns: full name, location, favorite food .... and many more). These two models have one-to-one association (:has_one, :belongs_to) between them and I have two problems :

1. When searching the User model, I also want to search UserProfile model.
2. I want to allow faceting based on few columns in UserProfile lets say location and favorite food.

    

Fabio Confalonieri has written a small hack for the solution to both the problems along with good explanation.

Tips:

1. Wanna see the statistics for created index?
   Download

2. If your search results are not good enough because the text is not indexed properly, it might be due to presence of acronyms or words having apostrophes or html content in your data. Solr provides you with many options for analyzing and modifying text before it is indexed and searched. Read these options at Solr's Wiki page. Remember, you need to make these modifications in schema.xml file.

3. Note : The default behaviour of acts_as_solr is to index model objects automatically upon save or update of a record.

<!---->

this xsl file as luke.xsl to vendor/plugins/acts_as_solr/solr/solr/conf/xslt/ and then open url: http://localhost:8982/solr/admin/luke?wt=xslt&tr=luke.xsl