Use ipython's own shell_expand

Fixes #194

.gitignore

@@ -35,4 +35,6 @@ nosetests.xml
 .pydevproject
 
 # Pycharm
-/.idea
+/.idea
+
+.venv

HACKING.txt

@@ -4,6 +4,9 @@ Development setup
 Running nose tests with IPython is tricky, so there's a
 run_tests.sh script for it.
 
+    pip install -e .
+    ./run_tests.sh
+
 To temporarily insert breakpoints for debugging: `from nose.tools import set_trace; set_trace()`
 
 Tests have requirements not installed by setup.py:

src/sql/magic.py

@@ -147,16 +147,18 @@ class SqlMagic(Magics, Configurable):
 
         """
         # Parse variables (words wrapped in {}) for %%sql magic (for %sql this is done automatically)
-        cell_variables = [
-            fn for _, fn, _, _ in Formatter().parse(cell) if fn is not None
-        ]
-        cell_params = {}
-        for variable in cell_variables:
-            if variable in local_ns:
-                cell_params[variable] = local_ns[variable]
-            else:
-                raise NameError(variable)
-        cell = cell.format(**cell_params)
+        cell = self.shell.var_expand(cell)
+
+        # cell_variables = [
+        #     fn for _, fn, _, _ in Formatter().parse(cell) if fn is not None
+        # ]
+        # cell_params = {}
+        # for variable in cell_variables:
+        #     if variable in local_ns:
+        #         cell_params[variable] = local_ns[variable]
+        #     else:
+        #         raise NameError(variable)
+        # cell = cell.format(**cell_params)
 
         line = sql.parse.without_sql_comment(parser=self.execute.parser, line=line)
         args = parse_argstring(self.execute, line)

src/tests/test_magic.py

@@ -370,3 +370,20 @@ def test_multiline_bracket_var_substitution(ip):
         """,
     )
     assert not result
+
+def test_json_in_select(ip):
+    # Variable expansion does not work within json, but 
+    # at least the two usages of curly braces do not collide
+    ip.user_global_ns["person"] = "prince"
+    result = ip.run_cell_magic(
+        "sql",
+        "",
+        """
+        sqlite:// 
+        SELECT
+          '{"greeting": "Farewell sweet {person}"}' 
+        AS json
+        """,
+    )
+    assert ('{"greeting": "Farewell sweet {person}"}',)
+