Merge pull request #35 from datafold/apr1

Various changes

Author: erezsh

sqeleton/databases/base.py

@@ -316,6 +316,10 @@ class Database(AbstractDatabase[T]):
     def name(self):
         return type(self).__name__
 
+    def compile(self, sql_ast):
+        compiler = Compiler(self)
+        return compiler.compile(sql_ast)
+
     def query(self, sql_ast: Union[Expr, Generator], res_type: type = None):
         """Query the given SQL code/AST, and attempt to convert the result to type 'res_type'
 
@@ -381,6 +385,8 @@ def query(self, sql_ast: Union[Expr, Generator], res_type: type = None):
                 return [_one(row) for row in res]
             elif res_type.__args__ in [(Tuple,), (tuple,)]:
                 return [tuple(row) for row in res]
+            elif res_type.__args__ == (dict,):
+                return [dict(safezip(res.columns, row)) for row in res]
             else:
                 raise ValueError(res_type)
         return res

sqeleton/queries/api.py

@@ -8,7 +8,7 @@
 this = This()
 
 
-def join(*tables: ITable):
+def join(*tables: ITable) -> Join:
     """Inner-join a sequence of table expressions"
 
     When joining, it's recommended to use explicit tables names, instead of `this`, in order to avoid potential name collisions.
@@ -110,6 +110,11 @@ def max_(expr: Expr):
     return Func("max", [expr])
 
 
+def exists(expr: Expr):
+    """Call EXISTS(expr)"""
+    return Func("exists", [expr])
+
+
 def if_(cond: Expr, then: Expr, else_: Optional[Expr] = None):
     """Conditional expression, shortcut to when-then-else.
 

sqeleton/queries/ast_classes.py

@@ -91,7 +91,7 @@ class ITable(AbstractTable):
     source_table: Any
     schema: Schema = None
 
-    def select(self, *exprs, distinct=SKIP, optimizer_hints=SKIP, **named_exprs):
+    def select(self, *exprs, distinct=SKIP, optimizer_hints=SKIP, **named_exprs) -> "ITable":
         """Create a new table with the specified fields"""
         exprs = args_as_tuple(exprs)
         exprs = _drop_skips(exprs)
@@ -248,6 +248,12 @@ def test_regex(self, other):
     def sum(self):
         return Func("SUM", [self])
 
+    def max(self):
+        return Func("MAX", [self])
+
+    def min(self):
+        return Func("MIN", [self])
+
 
 @dataclass
 class TestRegex(ExprNode, LazyOps):
@@ -261,7 +267,7 @@ def compile(self, c: Compiler) -> str:
         return c.compile(regex)
 
 
-@dataclass
+@dataclass(eq=False)
 class Func(ExprNode, LazyOps):
     name: str
     args: Sequence[Expr]
@@ -525,7 +531,7 @@ def schema(self):
         s = self.source_tables[0].schema  # TODO validate types match between both tables
         return type(s)({c.name: c.type for c in self.columns})
 
-    def on(self, *exprs):
+    def on(self, *exprs) -> "Join":
         """Add an ON clause, for filtering the result of the cartesian product (i.e. the JOIN)"""
         if len(exprs) == 1:
             (e,) = exprs
@@ -538,7 +544,7 @@ def on(self, *exprs):
 
         return self.replace(on_exprs=(self.on_exprs or []) + exprs)
 
-    def select(self, *exprs, **named_exprs):
+    def select(self, *exprs, **named_exprs) -> ITable:
         """Select fields to return from the JOIN operation
 
         See Also: ``ITable.select()``

sqeleton/utils.py

@@ -130,7 +130,7 @@ def __repr__(self) -> str:
 
 class CaseSensitiveDict(dict, CaseAwareMapping):
     def get_key(self, key):
-        self[key]  # Throw KeyError is key doesn't exist
+        self[key]  # Throw KeyError if key doesn't exist
         return key
 
     def as_insensitive(self):