module Sequel::Dataset::PreparedStatementMethods

  1. lib/sequel/dataset/prepared_statements.rb

Backbone of the prepared statement support. Grafts bind variable support into datasets by hijacking literal and using placeholders. By default, emulates prepared statements and bind variables by taking the hash of bind variables and directly substituting them into the query, which works on all databases, as it is no different from using the dataset without bind variables.

Public Instance methods

call (bind_vars=OPTS, &block)

Sets the prepared_args to the given hash and runs the prepared statement.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
117 def call(bind_vars=OPTS, &block)
118   bind(bind_vars).run(&block)
119 end
columns ()

Send the columns to the original dataset, as calling it on the prepared statement can cause problems.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
130 def columns
131   orig_dataset.columns
132 end
delayed_evaluation_sql_append (sql, delay)

Disallow use of delayed evaluations in prepared statements.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
135 def delayed_evaluation_sql_append(sql, delay)
136   raise Error, "delayed evaluations cannot be used in prepared statements" if @opts[:no_delayed_evaluations]
137   super
138 end
inspect ()

Programmer friendly string showing this is a prepared statement, with the prepared SQL it represents (which in general won't have substituted variables).

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
176 def inspect
177   "<#{visible_class_name}/PreparedStatement #{prepared_sql.inspect}>"
178 end
literal_symbol_append (sql, v)

Changes the values of symbols if they start with $ and prepared_args is present. If so, they are considered placeholders, and they are substituted using prepared_arg.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
165 def literal_symbol_append(sql, v)
166   if @opts[:bind_vars] && /\A\$(.*)\z/ =~ v
167     literal_append(sql, prepared_arg($1.to_sym))
168   else
169     super
170   end
171 end
log_sql ()

Whether to log the full SQL query. By default, just the prepared statement name is generally logged on adapters that support native prepared statements.

[show source]
   # File lib/sequel/dataset/prepared_statements.rb
89 def log_sql
90   @opts[:log_sql]
91 end
orig_dataset ()

The dataset that created this prepared statement.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
105 def orig_dataset
106   @opts[:orig_dataset]
107 end
prepare (*)

Raise an error if attempting to call prepare on an already prepared statement.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
123 def prepare(*)
124   raise Error, "cannot prepare an already prepared statement" unless allow_preparing_prepared_statements?
125   super
126 end
prepared_args ()

The array/hash of bound variable placeholder names.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
100 def prepared_args
101   @opts[:prepared_args]
102 end
prepared_modify_values ()

The argument to supply to insert and update, which may use placeholders specified by prepared_args

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
111 def prepared_modify_values
112   @opts[:prepared_modify_values]
113 end
prepared_sql ()

Returns the SQL for the prepared statement, depending on the type of the statement and the prepared_modify_values.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
142 def prepared_sql
143   case prepared_type
144   when :select, :all, :each
145     # Most common scenario, so listed first.
146     select_sql
147   when :first, :single_value
148     clone(:limit=>1).select_sql
149   when :insert_select
150     insert_select_sql(*prepared_modify_values)
151   when :insert, :insert_pk
152     insert_sql(*prepared_modify_values)
153   when :update
154     update_sql(*prepared_modify_values)
155   when :delete
156     delete_sql
157   else
158     select_sql
159   end
160 end
prepared_type ()

The type of prepared statement, should be one of :select, :first, :insert, :update, :delete, or :single_value

[show source]
   # File lib/sequel/dataset/prepared_statements.rb
95 def prepared_type
96   @opts[:prepared_type]
97 end

Protected Instance methods

run (&block)

Run the method based on the type of prepared statement.

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
183 def run(&block)
184   case prepared_type
185   when :select, :all
186     all(&block)
187   when :each
188     each(&block)
189   when :insert_select
190     with_sql(prepared_sql).first
191   when :first
192     first
193   when :insert, :update, :delete
194     if opts[:returning] && supports_returning?(prepared_type)
195       returning_fetch_rows(prepared_sql)
196     elsif prepared_type == :delete
197       delete
198     else
199       public_send(prepared_type, *prepared_modify_values)
200     end
201   when :insert_pk
202     fetch_rows(prepared_sql){|r| return r.values.first}
203   when Array
204     case prepared_type[0]
205     when :map, :as_hash, :to_hash, :to_hash_groups
206       public_send(*prepared_type, &block) 
207     end
208   when :single_value
209     single_value
210   else
211     raise Error, "unsupported prepared statement type used: #{prepared_type.inspect}"
212   end
213 end