Class: JsonApiPgSql

Inherits:
Object
  • Object
show all
Defined in:
lib/active_model_serializers/adapter/json_api_pg.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(base_serializer, base_relation, instance_options, options) ⇒ JsonApiPgSql

Returns a new instance of JsonApiPgSql.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 370

def initialize(base_serializer, base_relation, instance_options, options)
  @base_relation = base_relation
  @instance_options = instance_options
  @options = options

  # Make a JsonThing for everything,
  # cached as the full_name:

  # Watch out: User.where is a Relation, but plain User is not:
  ar_class = ActiveRecord::Relation === base_relation ? base_relation.klass : base_relation

  case base_serializer
  when ActiveModel::Serializer::CollectionSerializer
    ActiveModelSerializers::Adapter::JsonApiPg.warn_about_collection_serializer
    base_serializer = base_serializer.element_serializer
    @many = true
  when ActiveModelSerializersPg::CollectionSerializer
    base_serializer = base_serializer.element_serializer
    @many = true
  else
    base_serializer = base_serializer.class
    @many = false
  end
  base_serializer ||= ActiveModel::Serializer.serializer_for(ar_class.new, options)
  @base_serializer = base_serializer

  base_name = ar_class.name.underscore.pluralize
  base_thing = JsonThing.new(ar_class, base_name, base_serializer, options)
  @fields_for = {}
  @attribute_fields_for = {}
  @reflection_fields_for = {}
  @json_things = {
    base: base_thing, # `base` is a sym but every other key is a string
  }
  @json_things[base_name] = base_thing
  # We don't need to add anything else to @json_things yet
  # because we'll lazy-build it via get_json_thing.
  # That lets us go as deep in the relationships as we need
  # without loading anything extra.
end

Instance Attribute Details

#base_relation ⇒ Object (readonly)

Returns the value of attribute base_relation.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 359

def base_relation
  @base_relation
end

#base_serializer ⇒ Object (readonly)

Returns the value of attribute base_serializer.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 359

def base_serializer
  @base_serializer
end

Class Method Details

.json_column_type ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 361

def self.json_column_type
  # These classes may not exist, depending on the Rails version:
  @@json_column_type = if Rails::VERSION::STRING >= '5.2'
                         'ActiveRecord::Type::Json'
                       else
                         'ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Json'
                       end.constantize
end

Instance Method Details

#_attribute_fields_for(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 766

def _attribute_fields_for(resource)
  attrs = Set.new(serializer_attributes(resource))
  # JSON:API always excludes the `id`
  # even if it's part of the serializer:
  attrs = attrs - [resource.primary_key.to_sym]
  fields_for(resource).select { |f| attrs.include? f }.to_a
end

#_fields_for(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 746

def _fields_for(resource)
  # Sometimes options[:fields] has plural keys and sometimes singular,
  # so try both:
  resource_key = resource.json_type.to_sym
  fields = @instance_options.dig :fields, resource_key
  if fields.nil?
    resource_key = resource.json_type.singularize.to_sym
    fields = @instance_options.dig :fields, resource_key
  end
  if fields.nil?
    # If the user didn't request specific fields, then give them all that appear in the serializer:
    fields = serializer_attributes(resource).to_a + serializer_reflections(resource).to_a
  end
  fields
end

#_reflection_fields_for(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 778

def _reflection_fields_for(resource)
  refls = Set.new(serializer_reflections(resource))
  fields_for(resource).select { |f| refls.include? f }.to_a
end

#attribute_fields_for(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 762

def attribute_fields_for(resource)
  @attribute_fields_for[resource.full_name] ||= _attribute_fields_for(resource)
end

#base_resource ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 691

def base_resource
  @json_things[:base]
end

#column_is_castable_to_jsonb?(column_class) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 484

def column_is_castable_to_jsonb?(column_class)
  column_class.is_a?(ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Hstore) or
    column_class.is_a?(self.class.json_column_type)
end

#column_is_castable_to_jsonb_array?(column_class) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 489

def column_is_castable_to_jsonb_array?(column_class)
  column_class.is_a?(ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Array) and
    column_is_castable_to_jsonb?(column_class.subtype)
end

#column_is_jsonb?(column_class) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 475

def column_is_jsonb?(column_class)
  column_class.is_a? ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Jsonb
end

#column_is_jsonb_array?(column_class) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 479

def column_is_jsonb_array?(column_class)
  column_class.is_a?(ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Array) and
    column_class.subtype.is_a?(ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Jsonb)
end

#fields_for(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 742

def fields_for(resource)
  @fields_for[resource.full_name] ||= _fields_for(resource)
end

#get_json_thing(resource, field) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 411

def get_json_thing(resource, field)
  refl_name = "#{resource.full_name}.#{field}"
  @json_things[refl_name] ||= resource.from_reflection(field)
end

#get_json_thing_from_base(field) ⇒ Object

Takes a dotted field name (not including the base resource) like we might find in options, and builds up all the JsonThings needed to get to the end.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 659

def get_json_thing_from_base(field)
  r = base_resource
  field.split('.').each do |f|
    r = get_json_thing(r, f)
  end
  r
end

#include_cte(resource) ⇒ Object

See note in _jbs_name method for why we split each thing into two CTEs.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 627

def include_cte(resource)
  parent = resource.parent
  <<~EOQ
    SELECT  DISTINCT ON ("#{resource.table_name}"."#{resource.primary_key}")
            "#{resource.table_name}".*
    FROM    "#{resource.table_name}"
    JOIN    "#{parent.cte_name}"
    ON      #{include_cte_join_condition(resource)}
    ORDER BY "#{resource.table_name}"."#{resource.primary_key}"
  EOQ
end

#include_cte_join_condition(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 615

def include_cte_join_condition(resource)
  parent = resource.parent
  if resource.belongs_to?
    %Q{"#{parent.cte_name}"."#{resource.foreign_key}" = "#{resource.table_name}"."#{resource.primary_key}"}
  elsif resource.has_many? or resource.has_one?
    %Q{"#{parent.cte_name}"."#{parent.primary_key}" = "#{resource.table_name}"."#{resource.foreign_key}"}
  else
    raise "not supported relationship: #{resource.full_name}"
  end
end

#include_ctes ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 667

def include_ctes
  includes.map { |inc|
    # Be careful: inc might have dots:
    th = get_json_thing_from_base(inc)
    <<~EOQ
      "#{th.cte_name}" AS (
        #{include_cte(th)}
      ),
    EOQ
  }.join("\n")
end

#include_jbs(resource) ⇒ Object

See note in _jbs_name method for why we split each thing into two CTEs.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 640

def include_jbs(resource)
  <<~EOQ
    SELECT  "#{resource.table_name}".*,
            #{select_resource(resource)} AS j
    FROM    "#{resource.cte_name}" AS "#{resource.table_name}"
    #{join_resource_relationships(resource)}
  EOQ
end

#include_jbsses ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 679

def include_jbsses
  includes.map { |inc|
    # Be careful: inc might have dots:
    th = get_json_thing_from_base(inc)
    <<~EOQ
      "#{th.jbs_name}" AS (
        #{include_jbs(th)}
      ),
    EOQ
  }.join("\n")
end

#include_selects ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 603

def include_selects
  @include_selects ||= includes.map {|inc|
    th = get_json_thing_from_base(inc)
    # TODO: UNION ALL would be faster than UNION,
    # but then we still need to de-dupe when we have two paths to the same table,
    # e.g. buyer and seller for User.
    # But we could group those and union just them, or even better do a DISTINCT ON (id).
    # Since we don't get the id here that could be another CTE.
    %Q{UNION SELECT j FROM "#{th.jbs_name}"}
  }
end

#includes ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 649

def includes
  @includes ||= (@instance_options[:include] || []).sort_by do |inc|
    # Sort these by length so we never have bad foreign references in the CTEs:
    inc.size
  end
end

#join_resource_relationships(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 537

def join_resource_relationships(resource)
  fields = reflection_fields_for(resource)
  fields.map{|f|
    child_resource = get_json_thing(resource, f)
    refl = child_resource.reflection
    if refl.has_many?
      if refl.ar_reflection.present?
        # Preserve ordering options, either from the AR association itself
        # or from the class's default scope.
        # TODO: preserve the whole custom relation, not just ordering
        p = refl.ar_class.new
        ordering = nil
        ordering = p.send(refl.name).arel.orders
        ordering = child_resource.ar_class.default_scoped.arel.orders if ordering.empty?
        ordering = ordering.map{|o|
          case o
          # TODO: The gsub is pretty awful....
          when Arel::Nodes::Ordering
            o.to_sql.gsub("\"#{child_resource.table_name}\"", "rel")
          when String
            o
          else
            raise "Unknown type of ordering: #{o.inspect}"
          end
        }.join(', ').presence
        ordering = "ORDER BY #{ordering}" if ordering
        <<~EOQ
          LEFT OUTER JOIN LATERAL (
            SELECT  coalesce(jsonb_agg(jsonb_build_object('id', rel."#{child_resource.primary_key}"::text,
                                                          'type', '#{child_resource.json_type}') #{ordering}), '[]') AS j
            FROM    "#{child_resource.table_name}" rel
            WHERE   rel."#{child_resource.foreign_key}" = "#{resource.table_name}"."#{resource.primary_key}"
          ) "rel_#{child_resource.cte_name}" ON true
        EOQ
      elsif not refl.reflection_sql.nil?  # can't use .present? since that loads the Relation!
        case refl.reflection_sql
        when String
          raise "TODO"
        when ActiveRecord::Relation
          rel = refl.reflection_sql
          sql = rel.select(<<~EOQ).to_sql
            coalesce(jsonb_agg(jsonb_build_object('id', "#{child_resource.table_name}"."#{child_resource.primary_key}"::text,
                                                  'type', '#{child_resource.json_type}')), '[]') AS j
          EOQ
          <<~EOQ
            LEFT OUTER JOIN LATERAL (
              #{sql}
            ) "rel_#{child_resource.cte_name}" ON true
          EOQ
        end
      end
    elsif refl.has_one?
      <<~EOQ
        LEFT OUTER JOIN LATERAL (
          SELECT  jsonb_build_object('id', rel."#{child_resource.primary_key}"::text,
                                    'type', '#{child_resource.json_type}') AS j
          FROM    "#{child_resource.table_name}" rel
          WHERE   rel."#{child_resource.foreign_key}" = "#{resource.table_name}"."#{resource.primary_key}"
        ) "rel_#{child_resource.cte_name}" ON true
      EOQ
    else
      nil
    end
  }.compact.join("\n")
end

#json_key(name) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 420

def json_key(name)
  JsonThing.json_key(name)
end

#many? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 416

def many?
  @many
end

#maybe_select_resource_relationships(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 695

def maybe_select_resource_relationships(resource)
  rels_sql = select_resource_relationships(resource)
  if rels_sql.nil?
    ''
  else
    %Q{, 'relationships', #{rels_sql}}
  end
end

#reflection_fields_for(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 774

def reflection_fields_for(resource)
  @reflection_fields_for[resource.full_name] ||= _reflection_fields_for(resource)
end

#select_resource(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 704

def select_resource(resource)
  fields = fields_for(resource)
  <<~EOQ
    jsonb_build_object('id', "#{resource.table_name}"."#{resource.primary_key}"::text,
                       'type', '#{resource.json_type}',
                       'attributes', #{select_resource_attributes(resource)}
                       #{maybe_select_resource_relationships(resource)})
  EOQ
end

#select_resource_attribute(resource, field) ⇒ Object

Returns SQL for one JSON value for the resource’s ‘attributes’ object. If a field is an enum then we convert it from an int to a string. If a field has a #field__sql method on the ActiveRecord class, we use that instead.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 437

def select_resource_attribute(resource, field)
  typ = resource.ar_class.attribute_types[field.to_s]
  if typ.is_a? ActiveRecord::Enum::EnumType
    <<~EOQ
      CASE #{typ.as_json['mapping'].map{|str, int| %Q{WHEN "#{resource.table_name}"."#{field}" = #{int} THEN '#{str}'}}.join("\n     ")} END
    EOQ
  elsif resource.has_sql_method?(field)
    resource.sql_method(field)
  else
    field = resource.unaliased(field)
    # Standard AMS dasherizes json/jsonb/hstore columns,
    # so we have to do the same:
    if ActiveModelSerializers.config.key_transform == :dash
      cl = resource.ar_class.attribute_types[field.to_s]
      if column_is_jsonb? cl
        %Q{jsonb_dasherize("#{resource.table_name}"."#{field}")}
      elsif column_is_jsonb_array? cl
        # TODO: Could be faster:
        # If we made the jsonb_dasherize function smarter so it could handle jsonb[],
        # we wouldn't have to build a json object from the array then cast to jsonb[].
        %Q{jsonb_dasherize(array_to_json("#{resource.table_name}"."#{field}")::jsonb)}
      elsif column_is_castable_to_jsonb? cl
        # Fortunately we can cast hstore to jsonb,
        # which gives us a solution that works whether or not the hstore extension is installed.
        # Defining an hstore_dasherize function would work only if the extension were present.
        %Q{jsonb_dasherize("#{resource.table_name}"."#{field}"::jsonb)}
      elsif column_is_castable_to_jsonb_array? cl
        # TODO: Could be faster (see above):
        %Q{jsonb_dasherize(array_to_json("#{resource.table_name}"."#{field}"::jsonb[])::jsonb)}
      else
        %Q{"#{resource.table_name}"."#{field}"}
      end
    else
      %Q{"#{resource.table_name}"."#{field}"}
    end
  end
end

#select_resource_attributes(resource) ⇒ Object

Given a JsonThing and the fields you want, outputs the json column for a SQL SELECT clause.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 426

def select_resource_attributes(resource)
  fields = attribute_fields_for(resource)
  <<~EOQ
    jsonb_build_object(#{fields.map{|f| "'#{json_key(f)}', #{select_resource_attribute(resource, f)}"}.join(', ')})
  EOQ
end

#select_resource_relationship(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 502

def select_resource_relationship(resource)
  if resource.belongs_to?
    fk = %Q{"#{resource.parent.table_name}"."#{resource.foreign_key}"}
    <<~EOQ
      '#{resource.json_key}',
      jsonb_build_object('data',
                         CASE WHEN #{fk} IS NULL THEN NULL
                              ELSE jsonb_build_object('id', #{fk}::text,
                                                      'type', '#{resource.json_type}') END)
    EOQ
  elsif resource.has_many? or resource.has_one?
    refl = resource.reflection
    <<~EOQ
      '#{resource.json_key}',
       jsonb_build_object(#{refl.include_data ? %Q{'data', "rel_#{resource.cte_name}".j} : ''}
                          #{refl.include_data && refl.links.any? ? ',' : ''}
                          #{refl.links.any? ? %Q{'links',  jsonb_build_object(#{select_resource_relationship_links(resource, refl)})} : ''})
    EOQ
  else
    raise "Unknown kind of field reflection for #{resource.full_name}"
  end
end

#select_resource_relationship_links(resource, reflection) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 494

def select_resource_relationship_links(resource, reflection)
  reflection.links.map {|link_name, link_parts|
    <<~EOQ
      '#{link_name}', CONCAT(#{link_parts.join(%Q{, "#{resource.parent.table_name}"."#{resource.parent.primary_key}", })})
    EOQ
  }.join(",\n")
end

#select_resource_relationships(resource) ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 525

def select_resource_relationships(resource)
  fields = reflection_fields_for(resource)
  children = fields.map{|f| get_json_thing(resource, f)}
  if children.any?
    <<~EOQ
      jsonb_build_object(#{children.map{|ch| select_resource_relationship(ch)}.join(', ')})
    EOQ
  else
    nil
  end
end

#serializer_attributes(resource) ⇒ Object

Returns all the attributes listed in the serializer, after checking ‘include_foo?` methods.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 716

def serializer_attributes(resource)
  ms = Set.new(resource.serializer.instance_methods)
  resource.serializer._attributes.select{|f|
    if ms.include? "include_#{f}?".to_sym
      ser = resource.serializer.new(nil, @options)
      ser.send("include_#{f}?".to_sym)
    else
      true
    end
  }
end

#serializer_reflections(resource) ⇒ Object

Returns all the relationships listed in the serializer, after checking ‘include_foo?` methods.



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 730

def serializer_reflections(resource)
  ms = Set.new(resource.serializer.instance_methods)
  resource.serializer._reflections.keys.select{|f|
    if ms.include? "include_#{f}?".to_sym
      ser = resource.serializer.new(nil, @options)
      ser.send("include_#{f}?".to_sym)
    else
      true
    end
  }
end

#to_sql ⇒ Object 



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# File 'lib/active_model_serializers/adapter/json_api_pg.rb', line 783

def to_sql
  table_name = base_resource.table_name
  maybe_included = if include_selects.any?
                     %Q{, 'included', inc.j}
                   else
                     ''
                   end
  return <<~EOQ
    WITH
    t AS (
      #{base_relation.select(%Q{"#{base_resource.table_name}".*}).to_sql}
    ),
    t2 AS (
      #{many? ? "SELECT  COALESCE(jsonb_agg(#{select_resource(base_resource)}), '[]') AS j"
              : "SELECT                     #{select_resource(base_resource)}         AS j"}
      FROM    t AS "#{base_resource.table_name}"
      #{join_resource_relationships(base_resource)}
    ),
    #{include_ctes}
    #{include_jbsses}
    all_jbsses AS (
      SELECT  '{}'::jsonb AS j
      WHERE   1=0
      #{include_selects.join("\n")}
    ),
    inc AS (
      SELECT  COALESCE(jsonb_agg(j), '[]') AS j
      FROM    all_jbsses
    )
	SELECT	jsonb_build_object('data', t2.j
                               #{maybe_included})
    FROM    t2
    CROSS JOIN  inc
EOQ
end