split perform_query and perform_exec

add DB::ExecResult to have a concurrency safety exec result
remove connection string from abstract DB::Connection

spec/std/db/db_spec.cr

@@ -36,24 +36,10 @@ describe DB do
     end
   end
 
-  it "exec should close statement" do
-    with_dummy do |db|
-      db.exec ""
-      DummyDriver::DummyResultSet.last_result_set.closed?.should be_true
-    end
-  end
-
   it "scalar should close statement" do
     with_dummy do |db|
       db.scalar "1"
       DummyDriver::DummyResultSet.last_result_set.closed?.should be_true
     end
   end
-
-  it "exec should perform statement" do
-    with_dummy do |db|
-      db.exec ""
-      DummyDriver::DummyResultSet.last_result_set.executed?.should be_true
-    end
-  end
 end

spec/std/db/dummy_driver.cr

@@ -6,6 +6,11 @@ class DummyDriver < DB::Driver
   end
 
   class DummyConnection < DB::Connection
+    getter connection_string
+
+    def initialize(@connection_string)
+    end
+
     def prepare(query)
       DummyStatement.new(self, query)
     end
@@ -26,12 +31,21 @@ class DummyDriver < DB::Driver
       super(driver)
     end
 
-    protected def perform(args : Slice(DB::Any))
+    protected def perform_query(args : Slice(DB::Any))
+      set_params args
+      DummyResultSet.new self, @query
+    end
+
+    protected def perform_exec(args : Slice(DB::Any))
+      set_params args
+      DB::ExecResult.new 0, 0
+    end
+
+    private def set_params(args)
       @params.clear
       args.each_with_index do |arg, index|
         @params[index] = arg
       end
-      DummyResultSet.new self, @query
     end
   end
 
@@ -42,7 +56,6 @@ class DummyDriver < DB::Driver
       super(statement)
       @iterator = query.split.map { |r| r.split(',') }.to_a.each
 
-      @executed = false
       @@last_result_set = self
     end
 
@@ -50,12 +63,7 @@ class DummyDriver < DB::Driver
       @@last_result_set.not_nil!
     end
 
-    def executed?
-      @executed
-    end
-
     def move_next
-      @executed = true
       @iterator.next.tap do |n|
         return false if n.is_a?(Iterator::Stop)
         @values = n.each

src/db/connection.cr

@@ -17,12 +17,8 @@ module DB
   abstract class Connection
     # TODO add IDLE status, for connection ppool management.
 
-    getter connection_string # TODO Remove
     @closed = false
 
-    def initialize(@connection_string) # TODO Remove
-    end
-
     # Closes this connection.
     def close
       raise "Connection already closed" if @closed # TODO make it no fail if closed
@@ -45,10 +41,6 @@ module DB
 
     include QueryMethods
 
-    # Returns the last inserted id through this connection.
-    abstract def last_insert_id : Int64 # TODO move to ExecResult record. plano. with last_rows. eagerly askit.
-
-
     protected abstract def perform_close # TODO do_close
   end
 end

src/db/db.cr

@@ -67,8 +67,10 @@ module DB
   # See `DB::TYPES` in `DB`. `Any` is a nillable version of the union of all types in `DB::TYPES`
   alias Any = Nil | String | Int32 | Int64 | Float32 | Float64 | Slice(UInt8)
 
-  # :nodoc:
+  # Result of a `#exec` statement.
+  record ExecResult, rows_affected, last_insert_id
 
+  # :nodoc:
   def self.driver_class(driver_name) # : Driver.class
     @@drivers.not_nil![driver_name]
   end

src/db/query_methods.cr

@@ -3,19 +3,22 @@ module DB
   # All methods accepts a `query : String` and a set arguments.
   #
   # Three kind of statements can be performed:
-  #  1. `#exec` waits no response from the database.
+  #  1. `#exec` waits no record response from the database. An `ExecResult` is returned.
-  #  2. `#scalar` reads a single value of the response. Use `#scalar?` if the response is nillable.
+  #  2. `#scalar` reads a single value of the response. A `DB::Any` is returned.
-  #  3. `#query` returns a ResultSet that allows iteration over the rows in the response and column information.
+  #  3. `#query` returns a `ResultSet` that allows iteration over the rows in the response and column information.
   #
-  # Arguments can be passed:
+  # Arguments can be passed by position
-  #  * by position: `db.query("SELECT name FROM ... WHERE age > ?", age)`
+  #
-  #  * by symbol: `db.query("SELECT name FROM ... WHERE age > :age", {age: age})`
+  # ```
-  #  * by string: `db.query("SELECT name FROM ... WHERE age > :age", {"age": age})`
+  # db.query("SELECT name FROM ... WHERE age > ?", age)
+  # ```
   #
   # Convention of mapping how arguments are mapped to the query depends on each driver.
   #
   # Including `QueryMethods` requires a `prepare(query) : Statement` method.
   module QueryMethods
+    abstract def prepare(query) : Statement
+
     # Returns a `ResultSet` for the `query`.
     # The `ResultSet` must be closed manually.
     def query(query, *args)

src/db/result_set.cr

@@ -47,11 +47,6 @@ module DB
     protected def do_close
     end
 
-    # Ensures it executes the query
-    def exec
-      move_next
-    end
-
     # Move the next row in the result.
     # Return `false` if no more rows are available.
     # See `#each`

src/db/statement.cr

@@ -6,10 +6,9 @@ module DB
   #
   # 1. Subclass `Statements`
   # 2. `Statements` are created from a custom driver `Connection#prepare` method.
-  # 3. `#begin_parameters` is called before the parameters are set.
+  # 3. `#perform_query` executes a query that is expected to return a `ResultSet`
-  # 4. `#add_parameter` methods helps to support 0-based positional arguments and named arguments
+  # 4. `#perform_exec` executes a query that is expected to return an `ExecResult`
-  # 5. After parameters are set `#perform` is called to return a `ResultSet`
+  # 6. `#do_close` is called to release the statement resources.
-  # 6. `#on_close` is called to release the statement resources.
   abstract class Statement
     getter connection
 
@@ -18,10 +17,14 @@ module DB
     end
 
     # See `QueryMethods#exec`
-    def exec(*args)
+    def exec
-      query(*args) do |rs|
+      perform_exec(Slice(Any).new(0)) # no overload matches ... with types Slice(NoReturn)
-        rs.exec
     end
+
+    # See `QueryMethods#exec`
+    def exec(*args)
+      # TODO better way to do it
+      perform_exec(args.to_a.to_unsafe.to_slice(args.size))
     end
 
     # See `QueryMethods#scalar`
@@ -55,12 +58,12 @@ module DB
 
     # See `QueryMethods#query`
     def query(*args)
-      execute *args
+      perform_query *args
     end
 
     # See `QueryMethods#query`
     def query(*args)
-      execute(*args).tap do |rs|
+      perform_query(*args).tap do |rs|
         begin
           yield rs
         ensure
@@ -69,13 +72,13 @@ module DB
       end
     end
 
-    private def execute : ResultSet
+    private def perform_query : ResultSet
-      perform(Slice(Any).new(0))
+      perform_query(Slice(Any).new(0)) # no overload matches ... with types Slice(NoReturn)
     end
 
-    private def execute(*args) : ResultSet
+    private def perform_query(*args) : ResultSet
       # TODO better way to do it
-      perform(args.to_a.to_unsafe.to_slice(args.size))
+      perform_query(args.to_a.to_unsafe.to_slice(args.size))
     end
 
     # Closes this statement.
@@ -95,7 +98,8 @@ module DB
       close
     end
 
-    protected abstract def perform(args : Slice(Any)) : ResultSet
+    protected abstract def perform_query(args : Slice(Any)) : ResultSet
+    protected abstract def perform_exec(args : Slice(Any)) : ExecResult
 
     protected def do_close
     end