Class: ForestAdminDatasourceMongoid::Utils::Pipeline::ReparentGenerator

Inherits:
Object
  • Object
show all
Includes:
Schema
Defined in:
lib/forest_admin_datasource_mongoid/utils/pipeline/reparent_generator.rb

Overview

Generate pipeline to query submodels. The operations make rotations in the documents so that the root is changed to the submodel without loosing the parent (which may be needed later on).

Class Method Summary collapse

Class Method Details

.reparent(model, stack) ⇒ Object 



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# File 'lib/forest_admin_datasource_mongoid/utils/pipeline/reparent_generator.rb', line 10

def self.reparent(model, stack)
  schema = MongoidSchema.from_model(model)

  stack.flat_map.with_index do |step, index|
    # If this is the first step in the stack and there are no fields to flatten, return an empty list
    next [] if index.zero? && step[:as_fields].empty?
    # If this is the first step in the stack, only flatten the provided fields without reparenting
    next unflatten(step[:as_fields]) if index.zero?

    local_schema = schema.get_sub_schema(step[:prefix])
    relative_prefix = if stack[index - 1][:prefix].nil?
                        step[:prefix]
                      else
                        step[:prefix][(stack[index - 1][:prefix].length + 1)..]
                      end

    result = if local_schema.is_array
               reparent_array(relative_prefix, local_schema.is_leaf)
             else
               reparent_object(relative_prefix, local_schema.is_leaf)
             end

    [*result, *unflatten(step[:as_fields])]
  end
end

.reparent_array(prefix, in_doc) ⇒ Object 



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# File 'lib/forest_admin_datasource_mongoid/utils/pipeline/reparent_generator.rb', line 36

def self.reparent_array(prefix, in_doc)
  [
    { '$unwind' => { 'path' => "$#{prefix}", 'includeArrayIndex' => 'index' } },
    {
      '$replaceRoot' => {
        'newRoot' => {
          '$mergeObjects' => [
            in_doc ? { 'content' => "$#{prefix}" } : "$#{prefix}",
            ConditionGenerator.tag_record_if_not_exist(
              prefix,
              {
                '_id' => { '$concat' => [{ '$toString' => '$_id' }, ".#{prefix}.",
                                         { '$toString' => '$index' }] },
                'parent_id' => '$_id',
                'parent' => '$$ROOT'
              }
            )
          ]
        }
      }
    }
  ]
end

.reparent_object(prefix, in_doc) ⇒ Object 



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# File 'lib/forest_admin_datasource_mongoid/utils/pipeline/reparent_generator.rb', line 60

def self.reparent_object(prefix, in_doc)
  [
    {
      '$replaceRoot' => {
        'newRoot' => {
          '$mergeObjects' => [
            in_doc ? { 'content' => "$#{prefix}" } : "$#{prefix}",
            ConditionGenerator.tag_record_if_not_exist(
              prefix,
              {
                '_id' => { '$concat' => [{ '$toString' => '$_id' }, ".#{prefix}"] },
                'parent_id' => '$_id',
                'parent' => '$$ROOT'
              }
            )
          ]
        }
      }
    }
  ]
end

.unflatten(as_fields) ⇒ Object 



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# File 'lib/forest_admin_datasource_mongoid/utils/pipeline/reparent_generator.rb', line 82

def self.unflatten(as_fields)
  return [] if as_fields.empty?

  chunk_size = 30
  add_fields = as_fields.map { |f| [f.gsub('.', '@@@'), "$#{f}"] }

  # MongoDB (DocumentDB) enforces a limit of 30 fields per $addFields stage.
  # We split the list into chunks of 30 to prevent errors.
  unflatten_results = add_fields.each_slice(chunk_size).map { |chunk| { '$addFields' => chunk.to_h } }

  unflatten_results << { '$project' => as_fields.to_h { |f| [f, 0] } }
end