Add Python wrapper for LogicalPlan::Union (#240)

* add union

* Make clippy happier

datafusion/tests/test_imports.py

@@ -44,6 +44,7 @@
     Aggregate,
     Sort,
     Analyze,
+    Union,
     Like,
     ILike,
     SimilarTo,
@@ -105,6 +106,7 @@ def test_class_module_is_datafusion():
         Limit,
         Filter,
         Analyze,
+        Union,
         Like,
         ILike,
         SimilarTo,

src/context.rs

@@ -605,7 +605,7 @@ impl PySessionContext {
         let plan = plan.plan.clone();
         let fut: JoinHandle<datafusion_common::Result<SendableRecordBatchStream>> =
             rt.spawn(async move { plan.execute(part, ctx) });
-        let stream = wait_for_future(py, fut).map_err(|e| py_datafusion_err(e))?;
+        let stream = wait_for_future(py, fut).map_err(py_datafusion_err)?;
         Ok(PyRecordBatchStream::new(stream?))
     }
 }

src/expr.rs

@@ -67,6 +67,7 @@ pub mod signature;
 pub mod sort;
 pub mod subquery;
 pub mod table_scan;
+pub mod union;
 
 /// A PyExpr that can be used on a DataFrame
 #[pyclass(name = "Expr", module = "datafusion.expr", subclass)]
@@ -266,5 +267,6 @@ pub(crate) fn init_module(m: &PyModule) -> PyResult<()> {
     m.add_class::<sort::PySort>()?;
     m.add_class::<analyze::PyAnalyze>()?;
     m.add_class::<empty_relation::PyEmptyRelation>()?;
+    m.add_class::<union::PyUnion>()?;
     Ok(())
 }

src/expr/signature.rs

@@ -19,6 +19,7 @@ use datafusion_expr::{TypeSignature, Volatility};
 use pyo3::prelude::*;
 
 #[pyclass(name = "Signature", module = "datafusion.expr", subclass)]
+#[allow(dead_code)]
 #[derive(Clone)]
 pub struct PySignature {
     type_signature: TypeSignature,

src/expr/union.rs

@@ -0,0 +1,85 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use datafusion_expr::logical_plan::Union;
+use pyo3::prelude::*;
+use std::fmt::{self, Display, Formatter};
+
+use crate::common::df_schema::PyDFSchema;
+use crate::expr::logical_node::LogicalNode;
+use crate::sql::logical::PyLogicalPlan;
+
+#[pyclass(name = "Union", module = "datafusion.expr", subclass)]
+#[derive(Clone)]
+pub struct PyUnion {
+    union_: Union,
+}
+
+impl From<Union> for PyUnion {
+    fn from(union_: Union) -> PyUnion {
+        PyUnion { union_ }
+    }
+}
+
+impl From<PyUnion> for Union {
+    fn from(union_: PyUnion) -> Self {
+        union_.union_
+    }
+}
+
+impl Display for PyUnion {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Union
+            \nInputs: {:?}
+            \nSchema: {:?}",
+            &self.union_.inputs, &self.union_.schema,
+        )
+    }
+}
+
+#[pymethods]
+impl PyUnion {
+    /// Retrieves the input `LogicalPlan` to this `Union` node
+    fn input(&self) -> PyResult<Vec<PyLogicalPlan>> {
+        Ok(Self::inputs(self))
+    }
+
+    /// Resulting Schema for this `Union` node instance
+    fn schema(&self) -> PyResult<PyDFSchema> {
+        Ok(self.union_.schema.as_ref().clone().into())
+    }
+
+    fn __repr__(&self) -> PyResult<String> {
+        Ok(format!("Union({})", self))
+    }
+
+    fn __name__(&self) -> PyResult<String> {
+        Ok("Union".to_string())
+    }
+}
+
+impl LogicalNode for PyUnion {
+    fn inputs(&self) -> Vec<PyLogicalPlan> {
+        self.union_
+            .inputs
+            .iter()
+            .map(|x| x.as_ref().clone().into())
+            .collect()
+    }
+}