Add a little script to show comme use of the databases.

spec/various-common-usages.cr

@@ -0,0 +1,79 @@
+require "./db-cars.cr"
+
+rootdb = "/tmp/test-db"
+
+db = DODB::Storage::Cached(Car).new rootdb
+#db = DODB::Storage::Common(Car).new rootdb, 2
+index_name     = db.new_index     "name",     &.name
+index_color    = db.new_partition "color",    &.color
+index_keywords = db.new_tags      "keywords", &.keywords
+
+car0 = Car.new "Corvet-0", "red",    ["shiny"]
+car1 = Car.new "Corvet-1", "red",    ["slow", "expensive"]
+car2 = Car.new "Corvet-2", "blue",   ["fast", "elegant"]
+car3 = Car.new "Corvet-3", "violet", ["expensive"]
+
+db << car0
+db << car1
+db << car2
+db << car3
+
+# Get a car from stored data based on its name.
+if (c = index_name.get?("Corvet-2")) == car2
+	puts "We found the Corvet-2: #{c}"
+else
+	puts "We didn't find the Corvet-2!!!"
+end
+
+# Get a car from stored data based on a keyword.
+if c = index_keywords.get?("elegant")
+	puts "We found the elegant car: #{c}"
+else
+	puts "We didn't find the elegant car!!!"
+end
+
+# All cached entries are dropped.
+# WARNING: the Storage::Cached database don't read anything on the filesystem and relies entirely
+#          on cached values. Therefore, clearing the caches means the database won't answer any request
+#          with the proper values. The content has to be read again through a reindex_everything! for example.
+#db.clear_cache!
+
+db = DODB::Storage::Cached(Car).new rootdb
+index_name     = db.new_index     "name",     &.name
+index_color    = db.new_partition "color",    &.color
+index_keywords = db.new_tags      "keywords", &.keywords
+db.reindex_everything!
+
+# Get a car from stored data based on its color.
+if index_color.get?("violet").size == 1
+	puts "We found the violet car"
+else
+	puts "We didn't find the violet car!!!"
+end
+
+# Get a car from stored data based on a keyword.
+list_of_cars = index_keywords.get?("expensive")
+if ! list_of_cars.nil? && list_of_cars.size > 0
+	puts "We found the expensive cars:"
+	list_of_cars.each { |car| puts "- #{car}" }
+else
+	puts "We didn't find the expensive car!!!"
+end
+
+# Loop over entries, filling up the cache for Storage.
+total_values = 0
+	db.each_with_key do |v, k|
+	total_values += 1
+end
+
+if total_values == 4
+	puts "We found all the values"
+else
+	puts "We didn't find all the values!!!"
+end
+
+FileUtils.rm_r rootdb
+
+# Caches should still have a single entry since we only searched through them only once.
+#index_name.data.size.should  eq 1
+#index_color.data.size.should eq 1