Add logging for executing queries (#134)

* Add logging for executing queries

Arguments are translated to Log::Metadata::Value via DB::Statement#arg_to_log method.

DB::Statement#before_query_or_exec & after_query_or_exec protected methods can be used to hook and run around the statement execution

* Move the metadata converter to a module

* Replace before/after with def_around_query_or_exec macro

* Update src/db/enumerable_concat.cr

Co-authored-by: Ary Borenszweig <asterite@gmail.com>

Co-authored-by: Ary Borenszweig <asterite@gmail.com>

spec/custom_drivers_types_spec.cr

@@ -48,11 +48,11 @@ class FooDriver < DB::Driver
   end
 
   class FooConnection < DB::Connection
-    def build_prepared_statement(query) : DB::Statement
-      FooStatement.new(self)
+    def build_prepared_statement(command) : DB::Statement
+      FooStatement.new(self, command)
     end
 
-    def build_unprepared_statement(query) : DB::Statement
+    def build_unprepared_statement(command) : DB::Statement
       raise "not implemented"
     end
   end
@@ -112,7 +112,7 @@ class BarDriver < DB::Driver
 
   class BarConnection < DB::Connection
     def build_prepared_statement(query) : DB::Statement
-      BarStatement.new(self)
+      BarStatement.new(self, query)
     end
 
     def build_unprepared_statement(query) : DB::Statement

spec/dummy_driver.cr

@@ -96,22 +96,22 @@ class DummyDriver < DB::Driver
   class DummyStatement < DB::Statement
     property params
 
-    def initialize(connection, @query : String, @prepared : Bool)
+    def initialize(connection, command : String, @prepared : Bool)
       @params = Hash(Int32 | String, DB::Any | Array(DB::Any)).new
-      super(connection)
-      raise DB::Error.new(query) if query == "syntax error"
+      super(connection, command)
+      raise DB::Error.new(command) if command == "syntax error"
     end
 
     protected def perform_query(args : Enumerable) : DB::ResultSet
       @connection.as(DummyConnection).check
       set_params args
-      DummyResultSet.new self, @query
+      DummyResultSet.new self, command
     end
 
     protected def perform_exec(args : Enumerable) : DB::ExecResult
       @connection.as(DummyConnection).check
       set_params args
-      raise DB::Error.new("forced exception due to query") if @query == "raise"
+      raise DB::Error.new("forced exception due to query") if command == "raise"
       DB::ExecResult.new 0i64, 0_i64
     end
 
@@ -149,9 +149,9 @@ class DummyDriver < DB::Driver
 
     @@last_result_set : self?
 
-    def initialize(statement, query)
+    def initialize(statement, command)
       super(statement)
-      @top_values = query.split.map { |r| r.split(',') }.to_a
+      @top_values = command.split.map { |r| r.split(',') }.to_a
       @column_count = @top_values.size > 0 ? @top_values[0].size : 2
 
       @@last_result_set = self

spec/statement_spec.cr

@@ -1,4 +1,5 @@
 require "./spec_helper"
+require "log/spec"
 
 describe DB::Statement do
   it "should build prepared statements" do
@@ -217,4 +218,40 @@ describe DB::Statement do
       end
     end
   end
+
+  describe "logging" do
+    it "exec with no arguments" do
+      Log.capture(DB::Log.source) do |logs|
+        with_dummy do |db|
+          db.exec "42"
+        end
+
+        entry = logs.check(:debug, /Executing query/i).entry
+        entry.data[:query].should eq("42")
+        entry.data[:args].as_a.should be_empty
+      end
+    end
+
+    it "query with arguments" do
+      Log.capture(DB::Log.source) do |logs|
+        with_dummy do |db|
+          db.exec "1, ?", args: ["a"]
+          db.exec "2, ?", "a"
+          db.exec "3, ?", ["a"]
+        end
+
+        entry = logs.check(:debug, /Executing query/i).entry
+        entry.data[:query].should eq("1, ?")
+        entry.data[:args][0].as_s.should eq("a")
+
+        entry = logs.check(:debug, /Executing query/i).entry
+        entry.data[:query].should eq("2, ?")
+        entry.data[:args][0].as_s.should eq("a")
+
+        entry = logs.check(:debug, /Executing query/i).entry
+        entry.data[:query].should eq("3, ?")
+        entry.data[:args][0][0].as_s.should eq("a")
+      end
+    end
+  end
 end