added more robust error handling

app/adapters/db_adapter.rb

@@ -9,19 +9,36 @@ class DbAdapter
   end
 
   def dbinfo
-    version = self.class.get("#{@url}/version").parsed_response
-    info = self.class.get("#{@url}/dbinfo").parsed_response
+    begin
+      resp = self.class.get("#{@url}/version")
+      return nil unless resp.success?
+      version = resp.parsed_response
+
+      resp = self.class.get("#{@url}/dbinfo")
+      return nil unless resp.success?
+      info = resp.parsed_response
+    rescue
+      return nil
+    end
+
     {
       version: version,
       size_db: info['size'],
       size_other: info['other'],
-      size_total: info["size"]+info["other"]+info["free"]+info["reserved"]
+      size_total: info['size'] + info['other'] + info['free'] + info['reserved']
     }
   end
+
   def schema
     # GET extended info stream list
-    dump = self.class.get("#{@url}/stream/list?extended=1")
-    dump.parsed_response.map do |entry|
+    begin
+      resp = self.class.get("#{@url}/stream/list?extended=1")
+      return nil unless resp.success?
+    rescue
+      return nil
+    end
+
+    resp.parsed_response.map do |entry|
       metadata = if entry[0].match(UpdateStream.decimation_tag).nil?
                    __get_metadata(entry[0])
                  else
@@ -59,14 +76,16 @@ class DbAdapter
   def _set_path_metadata(path, data)
     params = { path: path,
                data: data }.to_json
-    response = self.class.post("#{@url}/stream/update_metadata",
-                               body: params,
-                               headers: { 'Content-Type' => 'application/json' })
-    if response.code != 200
-      Rails.logger.warn
-      "#{@url}: update_metadata(#{path})"\
-      " => #{response.code}:#{response.body}"
-
+    begin
+      response = self.class.post("#{@url}/stream/update_metadata",
+                                 body: params,
+                                 headers: { 'Content-Type' => 'application/json' })
+    rescue
+      return { error: true, msg: 'cannot contact NilmDB server' }
+    end
+    unless response.success?
+      Rails.logger.warn("#{@url}: update_metadata(#{path})"+
+                        " => #{response.code}:#{response.body}")
       return { error: true, msg: "error updating #{path} metadata" }
     end
     { error: false, msg: 'success' }
@@ -86,8 +105,9 @@ class DbAdapter
                        .slice('name', 'name_abbrev', 'description', 'hidden')
     # elements are called streams in the nilmdb metadata
     # and they don't have id or timestamp fields
-    attribs[:streams] = db_stream.db_elements.map {|e|
-      e.attributes.except("id","created_at","updated_at","db_stream_id")}
+    attribs[:streams] = db_stream.db_elements.map do |e|
+      e.attributes.except('id', 'created_at', 'updated_at', 'db_stream_id')
+    end
     { config_key__: attribs.to_json }.to_json
   end
 

app/controllers/db_folders_controller.rb

@@ -13,10 +13,11 @@ class DbFoldersController < ApplicationController
     adapter = DbAdapter.new(folder.db.url)
     service = EditFolder.new(adapter)
     service.run(folder, folder_params)
-    if(service.success?)
-      render json: folder, shallow: false
+    if service.success?
+      render json: {data: folder, messages: service}, shallow: false
     else
-      render json: service, status: :unprocessable_entity
+      render json: {data: nil, messages: service},
+             status: :unprocessable_entity
     end
   end
 

app/controllers/db_streams_controller.rb

@@ -8,9 +8,10 @@ class DbStreamsController < ApplicationController
     service = EditStream.new(adapter)
     service.run(stream, stream_params)
     if service.success?
-      render json: stream
+      render json: {data: stream, messages: service}
     else
-      render json: service, status: :unprocessable_entity
+      render json: {data: nil, messages: service},
+             status: :unprocessable_entity
     end
   end
 

app/controllers/dbs_controller.rb

@@ -14,7 +14,10 @@ class DbsController < ApplicationController
       if(prev_url != db.url || params[:refresh])
         refresh(db) and return
       end
-      render json: db
+      stub = StubService.new()
+      stub.add_notice("database updated")
+      render json: {data: db,
+                    messages: stub}
     else
       render json: "adfs"
     end
@@ -27,9 +30,10 @@ class DbsController < ApplicationController
       service = UpdateDb.new(db: db)
       service.run(adapter.dbinfo, adapter.schema)
       if(service.success?)
-        render json: db
+        render json: {data: db, messages: service}
       else
-        render json: service, status: :unprocessable_entity
+        render json: {data: nil, messages: service},
+          status: :unprocessable_entity
       end
     end
 

app/controllers/nilms_controller.rb

@@ -6,4 +6,9 @@ class NilmsController < ApplicationController
     nilms = Nilm.all
     render json: nilms
   end
+
+  def show
+    nilm = Nilm.find(params[:id])
+    render json: nilm
+  end
 end

app/models/db_element.rb

@@ -7,7 +7,7 @@ class DbElement < ApplicationRecord
 
   validates :name, presence: true
   validates :name, uniqueness: { scope: :db_stream_id,
-    message: ' is already used in this folder'}
+    message: ' is already used in this stream'}
 
   validates :scale_factor, presence: true, numericality: true
   validates :scale_factor, presence: true, numericality: true

app/models/db_stream.rb

@@ -52,7 +52,7 @@ class DbStream < ApplicationRecord
     self.description = ''
   end
 
-  
+
   def as_json(_options = {})
     stream = super(except: [:created_at, :updated_at])
     stream[:elements] = db_elements.map(&:as_json)

app/models/nilm.rb

@@ -6,6 +6,7 @@ class Nilm < ApplicationRecord
 
   def as_json(_options = {})
     nilm = super(except: [:created_at, :updated_at])
+    nilm[:available] = db.available
     nilm[:db] = db.as_json()
     nilm
   end

app/services/db/update_db.rb

@@ -10,6 +10,17 @@ class UpdateDb
   end
 
   def run(dbinfo, schema)
+
+    # check to make sure dbinfo and schema are set
+    # if either is nil, the database is not available
+    if(dbinfo.nil? || schema.nil?)
+      add_error("cannot contact database at #{@db.url}")
+      @db.update_attributes(available: false)
+      return self
+    else
+      @db.available = true
+    end
+
     # create the root folder if it doesn't exist
     @db.root_folder ||= DbFolder.create(db: @db, name: 'root', path: '/')
     @root_folder = @db.root_folder
@@ -26,6 +37,7 @@ class UpdateDb
     absorb_status(updater.run)
 
     @db.save
+    set_notice("Database refreshed")
     self
   end
 

app/services/db_folder/edit_folder.rb

@@ -30,6 +30,7 @@ class EditFolder
     end
     # everything went well, save the model
     db_folder.save!
+    set_notice("Folder updated")
     self
   end
 end

app/services/db_folder/update_folder.rb

@@ -55,6 +55,7 @@ class UpdateFolder
       byebug
     end
     @folder.save!
+    set_notice("Folder updated")
     self
   end
 

app/services/db_stream/edit_stream.rb

@@ -30,7 +30,8 @@ class EditStream
       return self
     end
     # everything went well, save the model
-    db_stream.save
+    db_stream.save!
+    set_notice("Stream updated")
     self
   end
 

app/services/db_stream/update_stream.rb

@@ -18,6 +18,7 @@ class UpdateStream
 
   def run
     __update_stream(@stream, @base_entry, @decimation_entries)
+    set_notice("Stream updated")
     self
   end
 

app/services/service_status.rb

 # frozen_string_literal: true
 
-# Handles service errors and warnings. Design pattern:
+# Handles service notices, errors and warnings. Design pattern:
 # All service action should occur in the run() function
 # Within run, call add_error or add_warning with string
 # messages. At the end of run() return the service object itself
@@ -9,8 +9,11 @@
 # the action parameter to NEVER_FAIL, FAIL_ON_WARNING, or
 # FAIL_ON_ERROR to determine when (if ever), absorb_status
 # returns false
+# Services should set a notice message when run successfully
+# eg "database updated"
+#
 module ServiceStatus
-  attr_reader :errors, :warnings
+  attr_reader :errors, :warnings, :notices
 
   FAIL_ON_ERROR   = 0
   FAIL_ON_WARNING = 1
@@ -19,6 +22,18 @@ module ServiceStatus
   def initialize
     @errors = []
     @warnings = []
+    @notices = []
+  end
+
+  def add_notice(message)
+    # ignore duplicates
+    return if @notices.include?(message)
+    @notices << String(message)
+  end
+
+  # clear out notices, and set to current message
+  def set_notice(message)
+    @notices = [message]
   end
 
   def add_error(message)
@@ -42,7 +57,7 @@ module ServiceStatus
   end
 
   def success?
-    !warnings? && !errors?
+    !errors?
   end
 
   def run
@@ -50,6 +65,7 @@ module ServiceStatus
   end
 
   def absorb_status(service, action: FAIL_ON_ERROR)
+    @notices += service.notices
     @warnings += service.warnings
     @errors += service.errors
     case action
@@ -63,6 +79,7 @@ module ServiceStatus
 
   def as_json(_options = {})
     {
+      notices: @notices,
       errors: @errors,
       warnings: @warnings
     }

app/services/stub_service.rb

+# frozen_string_literal: true
+
+# No run method, just implements messages
+# used by controllers that need to return messsages but do not
+# run a service (eg a simple update)
+class StubService
+  include ServiceStatus
+end

db/migrate/20170130022828_add_available_to_db.rb

+class AddAvailableToDb < ActiveRecord::Migration[5.0]
+  def change
+    add_column :dbs, :available, :boolean
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170127033854) do
+ActiveRecord::Schema.define(version: 20170130022828) do
 
   create_table "db_decimations", force: :cascade do |t|
     t.integer  "start_time",   limit: 8
@@ -83,6 +83,7 @@ ActiveRecord::Schema.define(version: 20170127033854) do
     t.integer  "size_other",          limit: 8
     t.string   "version"
     t.integer  "max_points_per_plot",           default: 3600
+    t.boolean  "available"
   end
 
   create_table "nilms", force: :cascade do |t|

spec/factories/db_element.rb

@@ -3,6 +3,9 @@
 # generic DbStream
 FactoryGirl.define do
   factory :db_element do
+    db_stream
     name { Faker::Lorem.word }
+    scale_factor 1.0
+    offset 0.0
   end
 end

spec/models/db_element_spec.rb

@@ -22,9 +22,9 @@ RSpec.describe 'DbElement' do
       expect(element.errors[:name].any?).to be true
     end
     it 'name is unique in stream' do
-      stream = DbStream.create(name: 'parent')
-      elem1 = DbElement.create(name: 'shared', db_stream: stream)
-      elem2 = DbElement.new(name: 'shared', db_stream: stream)
+      stream = FactoryGirl.create(:db_stream, name: 'parent')
+      elem1 = FactoryGirl.create(:db_element, name: 'shared', db_stream: stream)
+      elem2 = FactoryGirl.build(:db_element, name: 'shared', db_stream: stream)
       elem2.validate
       expect(elem2.errors[:name].any?).to be true
       # but if element is in a different stream its ok

spec/models/db_spec.rb

@@ -6,7 +6,8 @@ RSpec.describe 'Db' do
     let(:db) { Db.new }
     specify { expect(db).to respond_to(:url) }
     specify { expect(db).to respond_to(:root_folder) }
-    
+
+    specify { expect(db).to respond_to(:available) }
     specify { expect(db).to respond_to(:size_db) }
     specify { expect(db).to respond_to(:size_total) }
     specify { expect(db).to respond_to(:size_other) }

spec/services/db/update_db_spec.rb

@@ -24,7 +24,7 @@ simple_db = [
 ]
 
 describe 'UpdateDb' do
-  let(:dbinfo) { double('dbinfo').as_null_object}
+  let(:dbinfo) { {} }
   describe '*run*' do
     def update_with_schema(schema, db: nil)
       @db = db || Db.new

spec/services/db_stream/edit_stream_spec.rb

@@ -5,7 +5,7 @@ require 'rails_helper'
 describe 'EditStream service' do
   let(:db_adapter) { instance_double(DbAdapter) }
   let(:stream) { FactoryGirl.create(:db_stream, path: '/stream/path', name: 'old') }
-  let(:element) { DbElement.create(name: 'elem', db_stream: stream)}
+  let(:element) { FactoryGirl.create(:db_element, db_stream: stream)}
   let(:service) { EditStream.new(db_adapter) }
   # db adapter return values
   let(:success) { { error: false, msg: '' } }

spec/services/db_stream/update_stream_spec.rb

@@ -6,7 +6,7 @@ describe 'UpdateStream service' do
   let(:db) { Db.new }
   let(:service) { UpdateDb.new(db: db) }
   let(:helper) { DbSchemaHelper.new }
-  let(:mock_dbinfo) { double('dbinfo').as_null_object}
+  let(:mock_dbinfo) { {} }
 
   def build_entry(path, start, last, rows, width)
     helper.entry(path, start_time: start, end_time: last,
@@ -50,6 +50,10 @@ describe 'UpdateStream service' do
     schema = [helper.entry('/folder1/subfolder/stream',
                            element_count: 1)]
     schema[0][:elements][0][:name] = 'old_name'
+    # add mandatory metadata ow it will be rejected
+    schema[0][:elements][0][:scale_factor] = 1.0
+    schema[0][:elements][0][:offset] = 0.0
+
     service.run(mock_dbinfo, schema)
     element = DbElement.find_by_name('old_name')
     expect(element).to be_present

spec/services/folder/update_folder_spec.rb

@@ -6,7 +6,7 @@ describe 'UpdateFolder service' do
   let(:db) { Db.new }
   let(:service) { UpdateDb.new(db: db) }
   let(:helper) { DbSchemaHelper.new }
-  let(:mock_dbinfo) { double('dbinfo').as_null_object }
+  let(:mock_dbinfo) { {} }
 
   def build_entry(path, start, last, rows, width)
     helper.entry(path, start_time: start, end_time: last,