add query class and dsl for table service. resolves #56

lib/azure/storage.rb

@@ -18,4 +18,5 @@ module Azure::Storage; end
 require "azure/storage/blob/blob_service"
 require "azure/storage/queue/queue_service"
 require "azure/storage/table/table_service"
-require "azure/storage/table/batch"
+require "azure/storage/table/batch"
+require "azure/storage/table/query"

lib/azure/storage/table/query.rb

@@ -0,0 +1,105 @@
+#-------------------------------------------------------------------------
+# Copyright (c) Microsoft. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#--------------------------------------------------------------------------
+require 'azure/storage/table/table_service'
+
+module Azure
+  module Storage
+    module Table
+      class Query
+        def initialize(table="", partition=nil, row=nil, &block)
+          @table = table
+          @partition_key = partition
+          @row_key = row
+          @fields = []
+          @filters = []
+          @top_n = nil
+          @table_service = Azure::Storage::Table::TableService.new
+          self.instance_eval(&block) if block_given?
+        end
+          
+        attr_reader :table
+        attr_reader :partition_key
+        attr_reader :row_key
+
+        attr_reader :fields
+        attr_reader :filters
+        attr_reader :top_n
+
+        attr_reader :table_service
+
+        def from(table_name)
+          @table = table_name
+          self
+        end
+
+        def partition(partition_key)
+          @partition_key = partition_key
+          self
+        end
+
+        def row(row_key)
+          @row_key = row_key
+          self
+        end
+
+        def select(*p)
+          @fields.concat(p)
+          self
+        end
+
+        def where(*p)
+          @filters.push(p)
+          self
+        end
+        
+        def top(n)
+          @top_n = n
+          self
+        end
+
+        def execute
+          @table_service.query_entities(table, @partition_key, @row_key, fields.map{ |f| f.to_s }, _build_filter_string, (top_n ? top_n.to_i : top_n))
+        end
+
+        def _build_filter_string
+          result = ""
+          clauses = []
+          filters.each { |f|
+            clauses.push "#{f[0].to_s} #{f[1].to_s} #{value_exp(f[2])}"
+          }
+          return nil if clauses.length == 0 
+          
+          result << clauses.join(" and ")
+          result
+        end
+
+        def value_exp(v)
+          case v
+          when Float, Integer
+            v.to_s
+          when Date, Time, DateTime
+            "datetime'#{v.iso8601}'"
+          when TrueClass, FalseClass
+            v ? "true" : "false"
+          when GUID
+            "guid'#{v.to_s}'"
+          else
+            v.to_s
+          end
+        end
+      end
+    end
+  end
+end