diff --git a/README.md b/README.md
index ce4edb4..3f642eb 100644
--- a/README.md
+++ b/README.md
@@ -171,7 +171,7 @@ creates index with settings for each file from `indices` folder.
 - `rake elastics:migrate` (`.migrate`)
 puts mappings from `mappings` folder.
 
-- `rake elastics:migrate full=true` (`.migrate!`)
+- `rake elastics:migrate!` (`.migrate!`)
 performs full migration.
 
 - `rake elastics:reindex` (`.reindex`)
diff --git a/lib/elastics/active_record/helper_methods.rb b/lib/elastics/active_record/helper_methods.rb
index 0ed9621..7f2f3d0 100644
--- a/lib/elastics/active_record/helper_methods.rb
+++ b/lib/elastics/active_record/helper_methods.rb
@@ -10,26 +10,23 @@ def self.append_features(base)
       end
 
       module ClassMethods
+        # Performs `_search` request on type and instantiates result object.
+        # SearchResult is a default result class. It can be overriden with
+        # :result_class option.
         def search_elastics(data = {}, options = {})
-          request = {
-            id:   :_search,
-            body: data,
-          }
-          if routing = options[:routing]
-            request[:query] = {routing: routing}
-          end
-          SearchResult.new self, request_elastics(request), options
+          options[:result_class] ||= SearchResult
+          options[:model] = self
+          super
         end
 
+        # Finds items by ids and returns array in the order in which ids were given.
+        # Every missing record is replaced with `nil` in the result.
         def find_all_ordered(ids)
           items_by_id = where(id: ids).index_by(&:id)
           ids.map { |i| items_by_id[i] }
         end
 
-        def elastics_mapping
-          request_elastics(method: :get, id: :_mapping)
-        end
-
+        # Indexes all records in current scope.
         def index_all_elastics(*args)
           find_in_batches(*args) do |batch|
             index_batch_elastics(batch)
diff --git a/lib/elastics/active_record/search_result.rb b/lib/elastics/active_record/search_result.rb
index 1b55b7e..96fd79a 100644
--- a/lib/elastics/active_record/search_result.rb
+++ b/lib/elastics/active_record/search_result.rb
@@ -1,8 +1,8 @@
 module Elastics
   module ActiveRecord
     class SearchResult < Result::Search
-      def initialize(model, response, options = {})
-        @model = model
+      def initialize(response, options = {})
+        @model = options[:model]
         super response, options
       end
 
diff --git a/lib/elastics/model/helper_methods.rb b/lib/elastics/model/helper_methods.rb
index 1e1e0be..4d6083c 100644
--- a/lib/elastics/model/helper_methods.rb
+++ b/lib/elastics/model/helper_methods.rb
@@ -21,18 +21,37 @@ def elastics_params
           }
         end
 
+        # Proxies #request method to elastics client with specified index & type.
         def request_elastics(params)
           elastics.request(elastics_params.merge!(params))
         end
 
+        # Proxies #bulk method to elastics client with specified index & type.
         def bulk_elastics(params = {}, &block)
           elastics.bulk(elastics_params.merge!(params), &block)
         end
 
+        # Performs `_search` request on type and instantiates result object.
+        # Result::Search is a default result class. It can be overriden with
+        # :result_class option.
+        def search_elastics(data = {}, options = {})
+          request = {
+            id:     :_search,
+            body:   data,
+          }
+          if routing = options[:routing]
+            request[:query] = {routing: routing}
+          end
+          result_class = options[:result_class] || Result::Search
+          result_class.new request_elastics(request), options
+        end
+
+        # Performs `_refresh` request on index.
         def refresh_elastics
           request_elastics(method: :post, type: nil, id: :_refresh)
         end
 
+        # Indexes given records using batch API.
         def index_batch_elastics(batch)
           bulk_elastics do |bulk|
             batch.each do |record|
@@ -41,8 +60,20 @@ def index_batch_elastics(batch)
           end
         end
 
+        # Reindexes all records. It requires #find_in_batches method to be defined.
         def reindex_elastics(options = {})
-          raise 'Not implemented'
+          find_in_batches(options) do |batch|
+            index_batch_elastics(batch)
+          end
+        end
+
+        # Deletes all records in type keeping its mapping using "Delete by query" API.
+        def clear_elastics
+          request_elastics method: :delete, id: :_query, body: {query: {match_all: {}}}
+        end
+
+        def elastics_mapping
+          request_elastics(id: :_mapping)
         end
       end
 
diff --git a/lib/elastics/query_helper.rb b/lib/elastics/query_helper.rb
index ae9fdc6..8957180 100644
--- a/lib/elastics/query_helper.rb
+++ b/lib/elastics/query_helper.rb
@@ -1,11 +1,15 @@
 module Elastics
   module QueryHelper
+    # Combines multiple filters into `and` filter. Returns unmodified input
+    # unless it was an array.
     def normalize_filters(filters)
       return filters unless filters.is_a?(Array)
       return filters[0] if 2 > filters.size
       {and: {filters: filters}}
     end
 
+    # Wraps given query into `filtered` query if filter is present.
+    # Also replaces empty query with `match_all`.
     def normalize_query(query, filters)
       filter = normalize_filters filters
       query ||= {match_all: {}}
@@ -16,12 +20,20 @@ def normalize_query(query, filters)
       }}
     end
 
+    # Returns `term`(for scalar value) or `terms` (for array) query node
+    # for specified field.
     def terms_query(field, val, options = {})
       if val.is_a?(Array)
         {terms: {field => val}.merge(options)}
       else
-        result = {term: {field => val}}
+        {term: {field => val}}
       end
     end
+
+    # Returns `nil` if falsy value or empty array is given. Other way
+    # it returns term(s) query for it.
+    def terms_array_query(field, val, options = {})
+      terms_query(field, val, options) if val && (!val.is_a?(Array) || val.any?)
+    end
   end
 end
diff --git a/lib/elastics/tasks/mappings.rb b/lib/elastics/tasks/mappings.rb
index 89e93b5..85d0355 100644
--- a/lib/elastics/tasks/mappings.rb
+++ b/lib/elastics/tasks/mappings.rb
@@ -26,10 +26,34 @@ def mappings
           flatten.sort.
           each_with_object({}) do |file, hash|
             name = File.basename file, '.yml'
-            hash[name] = YAML.load_file(file)
+            hash[name] = fix_mapping(name, YAML.load_file(file))
           end
       end
 
+      # Adds missing type name in the top-level and updates properties definition.
+      # It allows to write
+      #
+      #     properties:
+      #       name: string
+      #       project_id: integer
+      #
+      # instead of
+      #
+      #     task:
+      #       properties:
+      #         name:
+      #           type: string
+      #         project_id:
+      #           type: integer
+      def fix_mapping(name, mapping)
+        mapping = {name => mapping} unless mapping.keys == [name]
+        properties = mapping[name]['properties']
+        properties && properties.each do |field, val|
+          properties[field] = {type: val} if val.is_a?(String)
+        end
+        mapping
+      end
+
       def types
         @types ||= mappings.keys
       end
diff --git a/lib/elastics/version.rb b/lib/elastics/version.rb
index f3b462d..f933b45 100644
--- a/lib/elastics/version.rb
+++ b/lib/elastics/version.rb
@@ -1,5 +1,5 @@
 module Elastics
-  VERSION = '0.4.0'
+  VERSION = '0.5.0'
 
   def self.gem_version
     Gem::Version.new VERSION
diff --git a/lib/tasks/elastics.rake b/lib/tasks/elastics.rake
index 4c522f1..c34d230 100644
--- a/lib/tasks/elastics.rake
+++ b/lib/tasks/elastics.rake
@@ -29,11 +29,11 @@ namespace 'elastics' do
 
   desc 'Creates indices and applies mappings. Full migration when param is present'
   task migrate: :load_config do
-    if ENV['full']
-      Elastics::Tasks.migrate! @elastics_options
-    else
-      Elastics::Tasks.migrate @elastics_options
-    end
+    Elastics::Tasks.migrate @elastics_options
+  end
+
+  task migrate!: :load_config do
+    Elastics::Tasks.migrate! @elastics_options
   end
 
   desc 'Reindex'