feat: add to_date function to StringValue (#9030)

## Description of changes

* Adds `to_date` to string types that accepts a format string and parses
a string to Date type.

* Uses a cast to timestamp and extract time as a fallback like this
```python
def visit_StringToDate(self, op, *, arg, format_str):
        return self.f.date(self.f.str_to_time(arg, format_str))
```
* Implements native functions for bigquery, clickhouse, MySQL, oracle,
postgres, and snowflake

## Issues closed
Implements half of #8908

---------

Co-authored-by: Gil Forsyth <gforsyth@users.noreply.github.com>

ibis/backends/clickhouse/compiler.py

@@ -37,6 +37,7 @@ class ClickHouseCompiler(SQLGlotCompiler):
             ops.Time,
             ops.TimeDelta,
             ops.StringToTimestamp,
+            ops.StringToDate,
             ops.Levenshtein,
         )
     )

ibis/backends/datafusion/compiler.py

@@ -59,6 +59,7 @@ class DataFusionCompiler(SQLGlotCompiler):
             ops.TimestampNow,
             ops.TypeOf,
             ops.Unnest,
+            ops.StringToDate,
             ops.StringToTimestamp,
         )
     )

ibis/backends/druid/compiler.py

@@ -67,6 +67,7 @@ class DruidCompiler(SQLGlotCompiler):
             ops.Strftime,
             ops.StringAscii,
             ops.StringSplit,
+            ops.StringToDate,
             ops.StringToTimestamp,
             ops.TimeDelta,
             ops.TimestampBucket,

ibis/backends/exasol/compiler.py

@@ -78,6 +78,7 @@ class ExasolCompiler(SQLGlotCompiler):
             ops.Strftime,
             ops.StringJoin,
             ops.StringSplit,
+            ops.StringToDate,
             ops.StringToTimestamp,
             ops.TimeDelta,
             ops.TimestampAdd,

ibis/backends/flink/compiler.py

@@ -82,6 +82,7 @@ class FlinkCompiler(SQLGlotCompiler):
         ops.RegexSearch: "regexp",
         ops.StrRight: "right",
         ops.StringLength: "char_length",
+        ops.StringToDate: "to_date",
         ops.StringToTimestamp: "to_timestamp",
         ops.Strip: "trim",
         ops.TypeOf: "typeof",

ibis/backends/mssql/compiler.py

@@ -113,6 +113,7 @@ class MSSQLCompiler(SQLGlotCompiler):
             ops.RPad,
             ops.StartsWith,
             ops.StringSplit,
+            ops.StringToDate,
             ops.StringToTimestamp,
             ops.StructColumn,
             ops.TimestampAdd,

ibis/backends/polars/compiler.py

@@ -936,6 +936,15 @@ def interval_from_integer(op, **kw):
     return _make_duration(arg, dt.Interval(unit=op.unit))
 
 
+@translate.register(ops.StringToDate)
+def string_to_date(op, **kw):
+    arg = translate(op.arg, **kw)
+    return arg.str.strptime(
+        dtype=pl.Date,
+        format=_literal_value(op.format_str),
+    )
+
+
 @translate.register(ops.StringToTimestamp)
 def string_to_timestamp(op, **kw):
     arg = translate(op.arg, **kw)

ibis/backends/snowflake/compiler.py

@@ -78,6 +78,7 @@ class SnowflakeCompiler(SQLGlotCompiler):
         ops.Hash: "hash",
         ops.Median: "median",
         ops.Mode: "mode",
+        ops.StringToDate: "to_date",
         ops.StringToTimestamp: "to_timestamp_tz",
         ops.TimeFromHMS: "time_from_parts",
         ops.TimestampFromYMDHMS: "timestamp_from_parts",

ibis/backends/sql/compiler.py

@@ -277,6 +277,7 @@ class SQLGlotCompiler(abc.ABC):
         ops.StringLength: "length",
         ops.StringReplace: "replace",
         ops.StringSplit: "split",
+        ops.StringToDate: "str_to_date",
         ops.StringToTimestamp: "str_to_time",
         ops.Tan: "tan",
         ops.Translate: "translate",
@@ -801,7 +802,6 @@ def visit_IntervalFromInteger(self, op, *, arg, unit):
         )
 
     ### String Instruments
-
     def visit_Strip(self, op, *, arg):
         return self.f.trim(arg, string.whitespace)
 

ibis/backends/sqlite/compiler.py

@@ -66,6 +66,7 @@ class SQLiteCompiler(SQLGlotCompiler):
             ops.TimestampAdd,
             ops.TimestampSub,
             ops.TimestampDiff,
+            ops.StringToDate,
             ops.StringToTimestamp,
             ops.TimeDelta,
             ops.DateDelta,

ibis/backends/tests/test_temporal.py

@@ -1441,6 +1441,85 @@ def test_string_to_timestamp(alltypes, fmt):
         assert val.strftime("%m/%d/%y") == result["date_string_col"][i]
 
 
+@pytest.mark.parametrize(
+    "fmt",
+    [
+        # "11/01/10" - "month/day/year"
+        param(
+            "%m/%d/%y",
+            id="mysql_format",
+            marks=[
+                pytest.mark.never(
+                    ["snowflake"],
+                    reason=(
+                        "(snowflake.connector.errors.ProgrammingError) 100096 (22007): "
+                        "Can't parse '11/01/10' as timestamp with format '%m/%d/%y'"
+                    ),
+                    raises=SnowflakeProgrammingError,
+                ),
+                pytest.mark.never(
+                    ["flink"],
+                    raises=ValueError,
+                    reason="Datetime formatting style is not supported.",
+                ),
+            ],
+        ),
+        param(
+            "MM/dd/yy",
+            id="pyspark_format",
+            marks=[
+                pytest.mark.never(
+                    ["bigquery"],
+                    reason="400 Mismatch between format character 'M' and string character '0'",
+                    raises=GoogleBadRequest,
+                ),
+                pytest.mark.never(
+                    ["mysql"],
+                    reason="NaTType does not support strftime",
+                    raises=ValueError,
+                ),
+                pytest.mark.never(
+                    ["trino"],
+                    reason="datetime formatting style not supported",
+                    raises=TrinoUserError,
+                ),
+                pytest.mark.never(
+                    ["polars"],
+                    reason="datetime formatting style not supported",
+                    raises=PolarsComputeError,
+                ),
+                pytest.mark.never(
+                    ["duckdb"],
+                    reason="datetime formatting style not supported",
+                    raises=DuckDBInvalidInputException,
+                ),
+            ],
+        ),
+    ],
+)
+@pytest.mark.notimpl(
+    [
+        "dask",
+        "pandas",
+        "clickhouse",
+        "sqlite",
+        "datafusion",
+        "mssql",
+        "druid",
+    ],
+    raises=com.OperationNotDefinedError,
+)
+@pytest.mark.notimpl(["exasol"], raises=com.OperationNotDefinedError)
+def test_string_to_date(alltypes, fmt):
+    table = alltypes
+    result = table.mutate(date=table.date_string_col.to_date(fmt)).execute()
+
+    # TEST: do we get the same date out, that we put in?
+    # format string assumes that we are using pandas' strftime
+    for i, val in enumerate(result["date"]):
+        assert val.strftime("%m/%d/%y") == result["date_string_col"][i]
+
+
 @pytest.mark.parametrize(
     ("date", "expected_index", "expected_day"),
     [

ibis/expr/operations/temporal.py

@@ -79,6 +79,15 @@ class StringToTimestamp(Value):
     dtype = dt.Timestamp(timezone="UTC")
 
 
+@public
+class StringToDate(Value):
+    arg: Value[dt.String]
+    format_str: Value[dt.String]
+
+    shape = rlz.shape_like("arg")
+    dtype = dt.date
+
+
 @public
 class ExtractTemporalField(TemporalUnary):
     dtype = dt.int32

ibis/expr/types/strings.py

@@ -1302,6 +1302,35 @@ def to_timestamp(self, format_str: str) -> ir.TimestampValue:
         """
         return ops.StringToTimestamp(self, format_str).to_expr()
 
+    def to_date(self, format_str: str) -> ir.DateValue:
+        """Parse a string and return a date.
+
+        Parameters
+        ----------
+        format_str
+            Format string in `strptime` format
+
+        Returns
+        -------
+        DateValue
+            Parsed date value
+
+        Examples
+        --------
+        >>> import ibis
+        >>> ibis.options.interactive = True
+        >>> t = ibis.memtable({"ts": ["20170206"]})
+        >>> t.ts.to_date("%Y%m%d")
+        ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
+        ┃ StringToDate(ts, '%Y%m%d') ┃
+        ┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
+        │ date                       │
+        ├────────────────────────────┤
+        │ 2017-02-06                 │
+        └────────────────────────────┘
+        """
+        return ops.StringToDate(self, format_str).to_expr()
+
     def protocol(self):
         """Parse a URL and extract protocol.