building slite

Author: veiled-coder

mysqlite/my_sqlite_request.rb

@@ -0,0 +1,133 @@
+require "csv"
+class MySqliteRequest
+attr_accessor :table_name, :table_data,:hashedDataB, :request, :columns ,:result_hash_array,:isWhere,:where_count,:isJoin,:column_on_db_a,:column_on_db_b,:filter_column, :filter_column_value
+def initialize
+@isWhere=false
+@isJoin=false
+@where_conditions=[]
+end
+
+def from (table) # expect(MySqliteRequest.new.from('database.csv')).to be_a(MySqliteRequest) 
+@table_name=table
+self
+end
+
+def self.from(table) #expect(MySqliteRequest.from('database.csv')).to be_a(MySqliteRequest) 
+MySqliteRequest.new.from(table)
+end
+
+def select(*variable_columns)# * this converts our parametrs to an array
+@request='select'
+@columns=variable_columns
+self
+end
+
+def where(column_name, value) # During the run() you will filter the result which match the value.
+@where_conditions<<{column_name=> value}  
+@isWhere=true
+self
+end
+
+def join(column_on_db_a, filename_db_b, column_on_db_b)
+    # Read filename_db_b table data
+    @isJoin=true
+    @hashedDataB = CSV.parse(File.read(filename_db_b), headers: true).map(&:to_h).take(200)
+    @column_on_db_a=column_on_db_a
+    @column_on_db_b=column_on_db_b
+   
+    self
+end
+  
+  
+
+def run
+    @result_hash_array=[] 
+    @joined_hash_array=[]
+    @filtered_hash_array=[]
+    
+        
+    #convert table data in CSV::Row to a HashedData
+    if @request==='select' # select the columns  from the each table row and corresponding data
+    @table_data=table_to_hashed(@table_name)
+        table_data.each do |current_row|
+            result_hash={}
+            @all_conditions_met=true;
+
+            process_row(current_row, result_hash, @result_hash_array, @columns)
+        
+
+            if @isWhere                
+                @where_conditions.each do |current_condition| #all where condtions will run for the current table row before the process_row runs
+                    current_condition.each do |key,value|   
+                        if current_row[key] != value         
+                                @all_conditions_met=false
+                                break
+                        end
+                    end
+                end
+            process_row(current_row, result_hash, @filtered_hash_array, @columns)if @all_conditions_met
+            end
+
+    end #end of table loop
+        puts @result_hash_array.inspect
+        # @result_hash_array=@filtered_hash_array
+        puts '...................filtered'
+        puts @filtered_hash_array
+    end #of request='select'
+    
+    # puts @filtered_hash_array.inspect
+
+    # if @isJoin 
+    #     @result_hash_array.each do |rowA|
+    #     @hashedDataB.each do |rowB|
+    #       if rowB[@column_on_db_b] == rowA[@column_on_db_a]
+    #         merged = rowA.merge(rowB)
+    #         @joined_hash_array<<merged
+    #       end
+    #     end
+    #   end  
+    #    @result_hash_array=@joined_hash_array
+    # end     
+     
+# puts @result_hash_array.inspect 
+end#of def run
+end#of class
+
+#HELPER FUNCTIONS
+
+def table_to_hashed(table_name)
+hashedData=CSV.parse(File.read(table_name),headers:true).map(&:to_h).take(3)
+return hashedData
+end
+
+def process_row(row,result_hash, result_hash_array,columns)
+    if  columns[0]==='*'
+        result_hash_array<<row
+   
+    else
+        columns.each do |column_name| 
+        result_hash[column_name]=row[column_name]
+
+        end
+    end  
+    result_hash_array << result_hash if result_hash != {}
+end
+
+# request = MySqliteRequest.new
+# request = request.from('nba_player_data.csv')
+# request = request.select('name')
+# request.run
+
+# request = MySqliteRequest.new
+# request = request.from('nba_player_data.csv')
+# request = request.select('name','college')
+# request = request.where('college', 'University of California')
+# request.run
+
+request = MySqliteRequest.new
+request = request.from('nba_player_data.csv')
+request = request.select('name','year_start','college')
+request = request.where('college', 'University of California')
+# request = request.where('year_start', '1997')
+# request =request.join('college','nba_players.csv','college')
+request.run