Class: Blogo::Paginator

Inherits:
Object
  • Object
show all
Defined in:
lib/blogo/paginator.rb

Overview

Does main calculation for pagination.

Examples:

# Current page is 3
paginator = Paginator.new(Post.all, page: 4, per_page: 3, size: 5)

# Displays 5 pages, since size = 5
paginator.pages # => [2, 3, 4, 5, 6]

# Previous page <<
paginator.prev_page # => 1

# Next page >>
paginator.prev_page # => 7

# Get items for the current page
paginator.items  # => 3 posts

Constant Summary collapse

DEFAULT_PER_PAGE =

:nodoc:

10
DEFAULT_PAGE =

:nodoc:

1
DEFAULT_SIZE =

:nodoc:

5

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(relation, opts = {}) ⇒ Paginator

Returns a new instance of Paginator.

Parameters:

  • relation (ActiveRecord::Realtion)
  • opts (Hash) (defaults to: {})

Options Hash (opts):

  • :per_page (Integer) —

    number of items display on 1 page

  • :page (Integer) —

    current page number

  • :size (Integer) —

    number of pages displayed with paginator



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# File 'lib/blogo/paginator.rb', line 37

def initialize(relation, opts = {})
  @relation = relation
  @per_page = (opts[:per_page] || DEFAULT_PER_PAGE).to_i
  @page     = (opts[:page]     || DEFAULT_PAGE).to_i
  @size     = (opts[:size]     || DEFAULT_SIZE).to_i
end

Instance Attribute Details

#page ⇒ Object (readonly)

Returns the value of attribute page.



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# File 'lib/blogo/paginator.rb', line 21

def page
  @page
end

#per_page ⇒ Object (readonly)

Returns the value of attribute per_page.



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# File 'lib/blogo/paginator.rb', line 21

def per_page
  @per_page
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/blogo/paginator.rb', line 21

def size
  @size
end

Instance Method Details

#items ⇒ Array<ActiveRecord::Base>

Fetch items for the current page.

Returns:

  • (Array<ActiveRecord::Base>) 


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# File 'lib/blogo/paginator.rb', line 47

def items
  @items ||= begin
    offset = @per_page * (@page - 1)
    @relation.limit(@per_page).offset(offset)
  end
end

#next_page ⇒ Integer?

Next page number. I used for >> link.

Returns:

  • (Integer, nil) 


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# File 'lib/blogo/paginator.rb', line 86

def next_page
  if pages.any? && pages_count > pages.last
    pages.last + 1
  end
end

#pages ⇒ Array<Integer>

Number of pages to display.

Returns:

  • (Array<Integer>) 


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# File 'lib/blogo/paginator.rb', line 57

def pages
  @pages ||= begin
    from = @page - (@size / 2).ceil
    from = 1 if from < 1
    upto = from + @size - 1

    # Correct +from+ and +to+ if +to+ is more than number of pages
    if upto > pages_count
      from -= (upto - pages_count)
      from = 1 if from < 1
      upto = pages_count
    end

    (from..upto).to_a
  end
end

#prev_page ⇒ Integer?

Previous page number. Is used for << link.

Returns:

  • (Integer, nil) 


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# File 'lib/blogo/paginator.rb', line 77

def prev_page
  first_page = pages.first.to_i
  first_page > 1 ? (first_page - 1) : nil
end