feat: Add IS NULL expression (#2468)

dozer-sql/expression/src/builder.rs

@@ -185,6 +185,14 @@ impl ExpressionBuilder {
                 )
                 .await
             }
+            SqlExpr::IsNull(expr) => {
+                self.parse_sql_isnull_operator(parse_aggregations, &false, expr, schema, udfs)
+                    .await
+            }
+            SqlExpr::IsNotNull(expr) => {
+                self.parse_sql_isnull_operator(parse_aggregations, &true, expr, schema, udfs)
+                    .await
+            }
             _ => Err(Error::UnsupportedExpression(expression.clone())),
         }
     }
@@ -1014,6 +1022,25 @@ impl ExpressionBuilder {
 
         Ok(in_list_expression)
     }
+
+    async fn parse_sql_isnull_operator(
+        &mut self,
+        parse_aggregations: bool,
+        negated: &bool,
+        expr: &Expr,
+        schema: &Schema,
+        udfs: &[UdfConfig],
+    ) -> Result<Expression, Error> {
+        let arg = self
+            .parse_sql_expression(parse_aggregations, expr, schema, udfs)
+            .await?;
+
+        if *negated {
+            Ok(Expression::IsNotNull { arg: Box::new(arg) })
+        } else {
+            Ok(Expression::IsNull { arg: Box::new(arg) })
+        }
+    }
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]

dozer-sql/expression/src/execution.rs

@@ -4,6 +4,7 @@ use crate::conditional::{get_conditional_expr_type, ConditionalExpressionType};
 use crate::datetime::{get_datetime_function_type, DateTimeFunctionType};
 use crate::error::Error;
 use crate::geo::common::{get_geo_function_type, GeoFunctionType};
+use crate::is_null::{evaluate_is_not_null, evaluate_is_null};
 use crate::json_functions::JsonFunctionType;
 use crate::operator::{BinaryOperatorType, UnaryOperatorType};
 use crate::scalar::common::{get_scalar_function_type, ScalarFunctionType};
@@ -84,6 +85,12 @@ pub enum Expression {
         results: Vec<Expression>,
         else_result: Option<Box<Expression>>,
     },
+    IsNull {
+        arg: Box<Expression>,
+    },
+    IsNotNull {
+        arg: Box<Expression>,
+    },
     #[cfg(feature = "python")]
     PythonUDF {
         name: String,
@@ -278,6 +285,8 @@ impl Expression {
             }
             #[cfg(feature = "javascript")]
             Expression::JavaScriptUdf(udf) => udf.to_string(schema),
+            Expression::IsNull { arg } => arg.to_string(schema) + " IS NULL ",
+            Expression::IsNotNull { arg } => arg.to_string(schema) + " IS NOT NULL ",
         }
     }
 }
@@ -365,6 +374,8 @@ impl Expression {
                 results,
                 else_result,
             } => evaluate_case(schema, operand, conditions, results, else_result, record),
+            Expression::IsNull { arg } => evaluate_is_null(schema, arg, record),
+            Expression::IsNotNull { arg } => evaluate_is_not_null(schema, arg, record),
             #[cfg(feature = "javascript")]
             Expression::JavaScriptUdf(udf) => udf.evaluate(record, schema),
         }
@@ -476,6 +487,18 @@ impl Expression {
             )),
             #[cfg(feature = "javascript")]
             Expression::JavaScriptUdf(udf) => Ok(udf.get_type()),
+            Expression::IsNull { arg: _ } => Ok(ExpressionType::new(
+                FieldType::Boolean,
+                false,
+                SourceDefinition::Dynamic,
+                false,
+            )),
+            Expression::IsNotNull { arg: _ } => Ok(ExpressionType::new(
+                FieldType::Boolean,
+                false,
+                SourceDefinition::Dynamic,
+                false,
+            )),
         }
     }
 }

dozer-sql/expression/src/is_null.rs

@@ -0,0 +1,50 @@
+use dozer_types::types::Record;
+use dozer_types::types::{Field, Schema};
+
+use crate::error::Error;
+use crate::execution::Expression;
+
+pub(crate) fn evaluate_is_null(
+    schema: &Schema,
+    expr: &mut Expression,
+    record: &Record,
+) -> Result<Field, Error> {
+    let field = expr.evaluate(record, schema)?;
+    Ok(Field::Boolean(field == Field::Null))
+}
+
+pub(crate) fn evaluate_is_not_null(
+    schema: &Schema,
+    expr: &mut Expression,
+    record: &Record,
+) -> Result<Field, Error> {
+    let field = expr.evaluate(record, schema)?;
+    Ok(Field::Boolean(field != Field::Null))
+}
+
+#[test]
+fn test_is_null() {
+    let mut value = Box::new(Expression::Literal(Field::Int(65)));
+    assert_eq!(
+        evaluate_is_null(&Schema::default(), &mut value, &Record::new(vec![])).unwrap(),
+        Field::Boolean(false)
+    );
+
+    let mut value = Box::new(Expression::Literal(Field::Null));
+    assert_eq!(
+        evaluate_is_null(&Schema::default(), &mut value, &Record::new(vec![])).unwrap(),
+        Field::Boolean(true)
+    );
+
+    let mut value = Box::new(Expression::Literal(Field::Int(65)));
+    assert_eq!(
+        evaluate_is_not_null(&Schema::default(), &mut value, &Record::new(vec![])).unwrap(),
+        Field::Boolean(true)
+    );
+
+    let mut value = Box::new(Expression::Literal(Field::Null));
+    assert_eq!(
+        evaluate_is_not_null(&Schema::default(), &mut value, &Record::new(vec![])).unwrap(),
+        Field::Boolean(false)
+    );
+}

dozer-sql/expression/src/lib.rs

@@ -10,6 +10,7 @@ pub mod error;
 pub mod execution;
 mod geo;
 mod in_list;
+mod is_null;
 mod json_functions;
 mod logical;
 mod mathematical;