Class: Blacklight::FacetPaginator

Inherits:
Object
  • Object
show all
Defined in:
app/models/blacklight/facet_paginator.rb

Overview

Pagination for facet values – works by setting the limit to max displayable. You have to ask Solr for limit+1, to get enough results to see if ‘more’ are available’. That is, the all_facet_values arg in constructor should be the result of asking solr for limit+1 values. This is a workaround for the fact that Solr itself can’t compute the total values for a given facet field, so we cannot know how many “pages” there are.

Direct Known Subclasses

Solr::FacetPaginator

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(all_facet_values, arguments = {}) ⇒ FacetPaginator

all_facet_values is a list of facet value objects returned by solr, asking solr for n+1 facet values. options: :limit => number to display per page, or (default) ?. Nil means

display all with no previous or next.

:offset => current item offset, default 0 :sort => ‘count’ or ‘index’, solr tokens for facet value sorting, default ‘count’.



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# File 'app/models/blacklight/facet_paginator.rb', line 31

def initialize(all_facet_values, arguments = {})
  # to_s.to_i will conveniently default to 0 if nil
  @offset = arguments[:offset].to_s.to_i
  @limit = arguments[:limit]
  @sort = arguments[:sort]
  @prefix = arguments[:prefix]

  @all = all_facet_values
end

Instance Attribute Details

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'app/models/blacklight/facet_paginator.rb', line 22

def limit
  @limit
end

#offset ⇒ Object (readonly)

Returns the value of attribute offset.



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# File 'app/models/blacklight/facet_paginator.rb', line 22

def offset
  @offset
end

#prefix ⇒ Object (readonly)

Returns the value of attribute prefix.



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# File 'app/models/blacklight/facet_paginator.rb', line 22

def prefix
  @prefix
end

#sort ⇒ Object (readonly)

Returns the value of attribute sort.



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# File 'app/models/blacklight/facet_paginator.rb', line 22

def sort
  @sort
end

Instance Method Details

#as_json(_ = nil) ⇒ Object 



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# File 'app/models/blacklight/facet_paginator.rb', line 101

def as_json(_ = nil)
  { 'items' => items.as_json, 'limit' => limit, 'offset' => offset, 'sort' => sort }
end

#current_page ⇒ Object 



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# File 'app/models/blacklight/facet_paginator.rb', line 54

def current_page
  # A nil limit is unlimited, thus only one page.
  if limit.nil? || limit.zero? # check for divide by zero
    1
  else
    (@offset / limit) + 1
  end
end

#first_page? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/models/blacklight/facet_paginator.rb', line 71

def first_page?
  current_page == 1
end

#items ⇒ Object 



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# File 'app/models/blacklight/facet_paginator.rb', line 46

def items
  items_for_limit(@all)
end

#last_page? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/models/blacklight/facet_paginator.rb', line 67

def last_page?
  limit.nil? || total_count <= limit
end

#next_page ⇒ Object 



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# File 'app/models/blacklight/facet_paginator.rb', line 63

def next_page
  current_page + 1 unless last_page?
end

#params_for_resort_url(sort_method, params = {}) ⇒ Object

Pass in a desired solr facet solr key (‘count’ or ‘index’, see wiki.apache.org/solr/SimpleFacetParameters#facet.limit under facet.sort ), and your current request params. Get back params suitable to passing to an ActionHelper method for creating a url, to resort by that method.

Parameters:

  • sort_method (String)
  • params (HashWithIndifferentAccess) (defaults to: {}) 


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# File 'app/models/blacklight/facet_paginator.rb', line 89

def params_for_resort_url(sort_method, params = {})
  # When resorting, we've got to reset the offset to start at beginning,
  # no way to make it make sense otherwise.
  resort_params = params.merge(request_keys[:sort] => sort_method, request_keys[:page] => nil)

  if sort_method == 'count'
    resort_params.except!(request_keys[:prefix])
  end

  resort_params
end

#prev_page ⇒ Object 



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# File 'app/models/blacklight/facet_paginator.rb', line 50

def prev_page
  current_page - 1 unless first_page?
end

#total_count ⇒ Object

The number of records solr gave us when we asked for limit + 1 records at the current offset



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# File 'app/models/blacklight/facet_paginator.rb', line 42

def total_count
  @all.size
end

#total_pages ⇒ Object

We’re implementing total_pages so that this matches the API from kaminari, even though we can’t know the total number of pages. github.com/amatsuda/kaminari/blob/v0.16.1/lib/kaminari/models/page_scope_methods.rb#L21



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# File 'app/models/blacklight/facet_paginator.rb', line 78

def total_pages
  -1
end