Implement truncate Date_Time for database backend (#8235)

Also adds some checks for column names generated for floor, ceil, truncate, round.

CHANGELOG.md

@@ -591,6 +591,7 @@
 - [Added XML support for `.to Table` and `.expand_column`.][8083]
 - [Added `Previous_Value` option to `fill_nothing` and `fill_empty`.][8105]
 - [Added `Table.format` for the in-memory backend.][8150]
+- [Implemented truncate `Date_Time` for database backend (Postgres only).][8235]
 
 [debug-shortcuts]:
   https://github.com/enso-org/enso/blob/develop/app/gui/docs/product/shortcuts.md#debug
@@ -844,6 +845,7 @@
 [8083]: https://github.com/enso-org/enso/pull/8083
 [8105]: https://github.com/enso-org/enso/pull/8105
 [8150]: https://github.com/enso-org/enso/pull/8150
+[8235]: https://github.com/enso-org/enso/pull/8235
 
 #### Enso Compiler
 

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Column.enso

@@ -810,9 +810,21 @@ type Column
              example_truncate = Examples.decimal_column.truncate
     truncate : Column ! Invalid_Value_Type
     truncate self =
-        Value_Type.expect_numeric self <| self.short_circuit_special_floating_point <|
-            new_name = self.naming_helper.function_name "truncate" [self]
-            self.make_unary_op "TRUNCATE" new_name
+        new_name = self.naming_helper.function_name "truncate" [self]
+        precise_value_type = self.inferred_precise_value_type
+        case precise_value_type.is_numeric of
+            True ->
+                self.short_circuit_special_floating_point <|
+                    self.make_unary_op "TRUNCATE" new_name
+            False -> case precise_value_type == Value_Type.Date_Time of
+                True ->
+                    op = "date_trunc_to_day"
+                    case self.connection.dialect.is_supported op of
+                        True ->
+                            self.make_unary_op op new_name
+                        False ->
+                            Error.throw (Unsupported_Database_Operation.Error ("`Column.truncate` for `Date_Time` is not supported by this connection."))
+                False -> Error.throw <| Invalid_Value_Type.Column "Numeric or Date_Time" self.value_type self.name
 
     ## GROUP Standard.Base.Rounding
        Takes the ceiling of floating-point values, returning integer values.
@@ -826,7 +838,7 @@ type Column
 
              import Standard.Examples
 
-             example_truncate = Examples.decimal_column.ceil
+             example_ceil = Examples.decimal_column.ceil
     ceil : Column ! Invalid_Value_Type
     ceil self =
         Value_Type.expect_numeric self <| self.short_circuit_special_floating_point <|
@@ -845,7 +857,7 @@ type Column
 
              import Standard.Examples
 
-             example_truncate = Examples.decimal_column.floor
+             example_floor = Examples.decimal_column.floor
     floor : Column ! Invalid_Value_Type
     floor self =
         Value_Type.expect_numeric self <| self.short_circuit_special_floating_point <|

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/Postgres/Postgres_Dialect.enso

@@ -295,7 +295,7 @@ make_internal_generator_dialect =
     stddev_pop = ["STDDEV_POP", Base_Generator.make_function "stddev_pop"]
     stddev_samp = ["STDDEV_SAMP", Base_Generator.make_function "stddev_samp"]
     stats = [agg_median, agg_mode, agg_percentile, stddev_pop, stddev_samp]
-    date_ops = [make_extract_as_int "year", make_extract_as_int "quarter", make_extract_as_int "month", make_extract_as_int "week", make_extract_as_int "day", make_extract_as_int "hour", make_extract_as_int "minute", make_extract_fractional_as_int "second", make_extract_fractional_as_int "millisecond" modulus=1000, make_extract_fractional_as_int "microsecond" modulus=1000, ["date_add", make_date_add], ["date_diff", make_date_diff]]
+    date_ops = [make_extract_as_int "year", make_extract_as_int "quarter", make_extract_as_int "month", make_extract_as_int "week", make_extract_as_int "day", make_extract_as_int "hour", make_extract_as_int "minute", make_extract_fractional_as_int "second", make_extract_fractional_as_int "millisecond" modulus=1000, make_extract_fractional_as_int "microsecond" modulus=1000, ["date_add", make_date_add], ["date_diff", make_date_diff], ["date_trunc_to_day", make_date_trunc_to_day]]
     special_overrides = [is_null, is_empty]
     other = [["RUNTIME_ERROR", make_runtime_error_op]]
     my_mappings = text + counts + stats + first_last_aggregators + arith_extensions + bool + date_ops + special_overrides + other
@@ -716,6 +716,11 @@ make_date_diff arguments (metadata : Date_Period_Metadata) =
                 as_int64 <|
                     ((extract_seconds ++ " * 1000000").paren ++ " + " ++ (micros ++ " % 1000000").paren).paren
 
+make_date_trunc_to_day arguments =
+    if arguments.length != 1 then Error.throw (Illegal_State.Error "date_trunc_to_day expects exactly one sub expression. This is a bug in Database library.") else
+        expr = arguments.at 0
+        Builder.code "(DATE_TRUNC('day'," ++ expr ++ ") :: DATE)"
+
 ## PRIVATE
    Alters the expression casting the value to a 64-bit integer.
 as_int64 expr =

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Column.enso

@@ -889,19 +889,19 @@ type Column
             col.truncate == dates
     truncate : Column ! Invalid_Value_Type
     truncate self =
+        new_name = naming_helper.function_name "truncate" [self]
         precise_value_type = self.inferred_precise_value_type
         case precise_value_type.is_numeric of
             True ->
                 case precise_value_type.is_integer of
                     True ->
-                        new_name = naming_helper.function_name "truncate" [self]
                         self.rename new_name
                     False ->
                         simple_unary_op self Java_Storage.Maps.TRUNCATE
             False -> case precise_value_type == Value_Type.Date_Time of
                 True ->
                     fun = _.date
-                    Column_Ops.map_over_storage self fun make_date_builder_adapter skip_nothing=True
+                    Column_Ops.map_over_storage self fun make_date_builder_adapter skip_nothing=True . rename new_name
                 False -> Error.throw <| Invalid_Value_Type.Column "Numeric or Date_Time" self.value_type self.name
 
     ## GROUP Standard.Base.Rounding

test/Table_Tests/src/Common_Table_Operations/Column_Operations_Spec.enso

@@ -25,6 +25,7 @@ main = run_default_backend spec
 spec setup =
     prefix = setup.prefix
     table_builder = setup.table_builder
+    pending_datetime = if setup.test_selection.date_time.not then "Date/Time operations are not supported by this backend."
 
     do_op n op =
         table = table_builder [["x", [n]]]
@@ -690,31 +691,37 @@ spec setup =
                 table = table_builder [["x", [0.1, 0.9, 3.1, 3.9, -0.1, -0.9, -3.1, -3.9]]]
                 result = table.at "x" . cast type . round
                 result.to_vector.should_equal [0, 1, 3, 4, 0, -1, -3, -4]
+                result.name . should_equal "round([x])"
 
             Test.specify "should allow round on a float column (to >0 decimal places)" <|
                 table = table_builder [["x", [0.51, 0.59, 3.51, 3.59, -0.51, -0.59, -3.51, -3.59]]]
                 result = table.at "x" . cast type . round 1
                 result.to_vector.should_equal [0.5, 0.6, 3.5, 3.6, -0.5, -0.6, -3.5, -3.6]
+                result.name . should_equal "round([x])"
 
             Test.specify "should allow round on a float column (to <0 decimal places)" <|
                 table = table_builder [["x", [51.2, 59.3, 351.45, 359.11, -51.2, -59.3, -351.23, -359.69]]]
                 result = table.at "x" . cast type . round -1
                 result.to_vector.should_equal [50.0, 60.0, 350.0, 360.0, -50.0, -60.0, -350.0, -360.0]
+                result.name . should_equal "round([x])"
 
             Test.specify "should allow truncate on a "+type.to_text+" column" <|
                 table = table_builder [["x", [0.1, 0.9, 3.1, 3.9, -0.1, -0.9, -3.1, -3.9]]]
                 result = table.at "x" . cast type . truncate
                 result.to_vector.should_equal [0, 0, 3, 3, 0, 0, -3, -3]
+                result.name . should_equal "truncate([x])"
 
             Test.specify "should allow ceil on a "+type.to_text+" column" <|
                 table = table_builder [["x", [0.1, 0.9, 3.1, 3.9, -0.1, -0.9, -3.1, -3.9]]]
                 result = table.at "x" . cast type . ceil
                 result.to_vector.should_equal [1, 1, 4, 4, 0, 0, -3, -3]
+                result.name . should_equal "ceil([x])"
 
             Test.specify "should allow floor on a "+type.to_text+" column" <|
                 table = table_builder [["x", [0.1, 0.9, 3.1, 3.9, -0.1, -0.9, -3.1, -3.9]]]
                 result = table.at "x" . cast type . floor
                 result.to_vector.should_equal [0, 0, 3, 3, -1, -1, -4, -4]
+                result.name . should_equal "floor([x])"
 
         test_floatlike Value_Type.Float
         if setup.test_selection.supports_decimal_type then
@@ -724,21 +731,25 @@ spec setup =
             table = table_builder [["x", [1, 9, 31, 39, -1, -9, -31, -39]]]
             result = table.at "x" . round -1
             result.to_vector.should_equal [0, 10, 30, 40, 0, -10, -30, -40]
+            result.name . should_equal "round([x])"
 
         Test.specify "should allow truncate on an int column" <|
             table = table_builder [["x", [0, 3, -3, 1, -2]]]
             result = table.at "x" . truncate
             result.to_vector.should_equal [0, 3, -3, 1, -2]
+            result.name . should_equal "truncate([x])"
 
         Test.specify "should allow ceil on an int column" <|
             table = table_builder [["x", [0, 3, -3, 1, -2]]]
             result = table.at "x" . ceil
             result.to_vector.should_equal [0, 3, -3, 1, -2]
+            result.name . should_equal "ceil([x])"
 
         Test.specify "should allow floor on an int column" <|
             table = table_builder [["x", [0, 3, -3, 1, -2]]]
             result = table.at "x" . floor
             result.to_vector.should_equal [0, 3, -3, 1, -2]
+            result.name . should_equal "floor([x])"
 
         Test.specify "should fail on decimal_places out of range" <|
             table = table_builder [["x", [0, 3, -3, 1, -2]]]
@@ -779,6 +790,16 @@ spec setup =
                 x.round . to_vector . should_equal [1, -2, 4]
                 x.truncate . to_vector . should_equal [1, -2, 3]
 
+    Test.group prefix+"Date truncation" pending=pending_datetime <|
+        Test.specify "should be able to truncate a column of Date_Times" <|
+            dates = [Date_Time.new 2020 10 24 1 2 3, Date_Time.new 2020 10 24 1 2 3]
+            table = table_builder [["foo", dates]]
+            table.at "foo" . value_type . should_equal (Value_Type.Date_Time with_timezone=True)
+            truncated = table.at "foo" . truncate
+            truncated . to_vector . should_equal [Date.new 2020 10 24, Date.new 2020 10 24]
+            truncated . value_type . should_equal Value_Type.Date
+            truncated.name . should_equal "truncate([foo])"
+
     Test.group prefix+"Text Column Operations" <|
         Test.specify "should handle operations like starts_with, ends_with, contains" <|
             with_mixed_columns_if_supported [["s1", ["foobar", "bar", "baz", "BAB", Nothing]], ["s2", ["foo", "ar", "a", "b", Nothing]]] t3->

test/Table_Tests/src/Database/SQLite_Spec.enso

@@ -222,6 +222,11 @@ sqlite_specific_spec prefix connection setup =
             do_round 231 . should_be_a Float
             do_round 231 -1 . should_be_a Float
 
+    Test.group prefix+"Column.const" <|
+        Test.specify "Does not support making a constant column from a Date" <|
+            t = table_builder [["x", ["1", "2", "3"]]]
+            t.at "x" . const (Date.new 12 4 12) . should_fail_with Unsupported_Database_Operation
+
 sqlite_spec connection prefix =
     name_counter = Ref.new 0
     table_builder columns =

test/Table_Tests/src/In_Memory/Column_Spec.enso

@@ -361,5 +361,7 @@ spec =
 
     Test.group "Date_Time truncate" <|
         Test.specify "should be able to truncate a column of Date_Times" <|
-            Column.from_vector "foo" [Date_Time.new 2020 10 24 1 2 3, Date_Time.new 2020 10 24 1 2 3] . truncate . should_equal <| Column.from_vector "foo" [Date.new 2020 10 24, Date.new 2020 10 24]
-            Column.from_vector "foo" [Date_Time.new 2020 10 24 1 2 3, Date_Time.new 2020 10 24 1 2 3] . truncate . value_type . should_equal Value_Type.Date
+            c = Column.from_vector "foo" [Date_Time.new 2020 10 24 1 2 3, Date_Time.new 2020 10 24 1 2 3]
+            truncated = c.truncate
+            truncated . should_equal <| Column.from_vector "truncate([foo])" [Date.new 2020 10 24, Date.new 2020 10 24]
+            truncated . value_type . should_equal Value_Type.Date