describe.rb in oci8_simple-0.5.0

- old
+ new
@@ -1,59 +1,131 @@
-class Oci8Simple::Describe
-  def initialize(env=nil)
-    @env = env || "development"
-  end
+module Oci8Simple
+  # == Description
+  # This class creates a string describing a table's columns, intended to be 
+  # displayed in a fixed-width font.
+  # == Usage
+  #   Oci8Simple::Describe.new("development").run("users")
+  class Describe
+    SPACE_BETWEEN=2
+    FIELDS=[
+      {:select => "NULLABLE",           :header => "Required", :content => :format_nullable, :right => true},
+      {:select => "lower(COLUMN_NAME)", :header=> "Name"},
+      {:select => "lower(DATA_TYPE)",   :header => "Type"},
+      {:select => "DATA_LENGTH",        :header => "Size", :content => :format_size},
+      {:select => "CHAR_USED",          :header => "Char?", :content => :format_char_used},   
+      {:select => "CHAR_LENGTH",        :header => "Char_size", :content => :format_char_length},
+      {:select => "DATA_PRECISION",     :header => "Precision"}, 
+      {:select => "DATA_SCALE",         :header => "Scale"},
+      {:select => "DATA_DEFAULT",       :header => "Default", :content => :format_default, :max => 10}
+    ]
   
-  def run(table)
-    description = client.conn.describe_table(table)
-    c = description.columns.sort{|a,b| a.name <=> b.name }
-    max_name = max(c.map(&:name)) + 3
-    max_type = max(c.map {|col| type_and_size(col)}) + 1
-    c.map do |col|
-      "\"#{col.name}\"".ljust(max_name, ' ') + type_and_size(col).ljust(max_type, ' ') + null(col)
-    end.map(&:upcase).join("\n")
-  end
+    def run(table)
+      sql = <<-SQL
+        select #{select_fields} 
+        from user_tab_columns 
+        where table_name='#{table.upcase}' 
+        order by column_name asc
+      SQL
+      results = client.run(sql)
+      calculate_widths(results)
+      format_results(results)
+    end
   
-  def null(col)
-    col.nullable? ? "" : "NOT NULL"
-  end
+    def initialize(env=nil)
+      @env = env || "development"
+    end
   
-  def type_and_size(col)
-    str = "#{col.data_type}"
-    if(col.data_type.to_s =~ /varchar/i)
-      str << "(#{col.char_size} CHAR)"
-    elsif(col.data_type == :number)
-      str << "(#{col.precision})"
+    def self.usage
+      "Usage: #{0} TABLE_NAME [ENVIRONMENT]"
     end
-    str
-  end
   
-  def max(arr)
-    arr.map(&:length).max
-  end
+    def self.run_from_argv
+      o = OptionParser.new do |opt|
+        opt.banner = usage
+        opt.on("-v", "--version", "Show version") do
+          puts "version #{File.read(File.join(File.dirname(__FILE__), '..', '..', 'VERSION'))}"
+          exit
+        end
+      end
+      o.parse!
+      if(ARGV[0].nil?)
+        puts o
+      else
+        puts self.new(ARGV[1]).run(ARGV[0])
+      end
+    end
   
-  def self.usage
-    "Usage: #{0} TABLE_NAME [ENVIRONMENT]"
-  end
+    private
   
-  def self.run_from_argv
-    o = OptionParser.new do |opt|
-      opt.banner = usage
-      opt.on("-v", "--version", "Show version") do
-        puts "version #{File.read(File.join(File.dirname(__FILE__), '..', '..', 'VERSION'))}"
-        exit
+    def format_nullable(value, row)
+      value == 'N' ? '*' : ' '
+    end
+
+    def format_char_used(value, row)
+      value == 'C' ? "*" : ' '
+    end
+  
+    def format_char_length(value, row)
+      row[FIELDS.index{|f| f[:select] == "CHAR_USED"}] == "C" ? value.to_s : ""
+    end
+  
+    def format_size(value, row)
+      row[FIELDS.index{|f| f[:select] == "lower(DATA_TYPE)"}] =~ /lob/i ? "" : value.to_s
+    end
+  
+    def format_default(value, row)
+      value = value.to_s.strip.gsub(/^'(.+)'$/,'\1')
+    
+      if(value.length > 10)
+        value = value[0..9] + "..."
       end
+      value
     end
-    o.parse!
-    if(ARGV[0].nil?)
-      puts o
-    else
-      puts self.new(ARGV[1]).run(ARGV[0])
+  
+    def select_fields
+      FIELDS.map{|f| f[:select]}.join(",")
     end
-  end
   
-  private
+    def max(column, header)
+      max = header.length
+      column.each {|s| max = s.length if s.length > max}
+      max + SPACE_BETWEEN
+    end
+
+    def header
+      FIELDS.map{|f| f[:header].ljust(f[:max], ' ')}.join("")
+    end
   
-  def client
-    @client ||= Oci8Simple::Client.new(@env)
+    def calculate_widths(results)
+      FIELDS.each_with_index do |hsh,i|
+        if(hsh[:max].nil?)
+          hsh[:max] = max(results.map{|row| row[i].to_s}, hsh[:header])
+        end
+      end
+    end
+  
+    def format_results(results)
+      arr = []
+      arr << header
+      arr << "-" * arr[0].length
+      results.each do |result|
+        str = ""
+        result.each_with_index do |col, i|
+          field = FIELDS[i]
+          value = field[:content].nil? ? col.to_s : send(field[:content], col, result)
+          if(field[:right])
+            str << value.rjust(field[:max] - SPACE_BETWEEN, ' ')
+            str << ' ' * SPACE_BETWEEN
+          else
+            str << value.ljust(field[:max], ' ')
+          end
+        end
+        arr << str
+      end
+      arr.join("\n")
+    end
+  
+    def client
+      @client ||= Oci8Simple::Client.new(@env)
+    end
   end
 end
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