feat: simple read write new json type values (#7175)

feat: basic json read and write

Signed-off-by: luofucong <luofc@foxmail.com>

src/common/sql/src/convert.rs

@@ -231,13 +231,15 @@ pub fn sql_value_to_value(
         }
     }
 
-    if value.data_type() != *data_type {
+    let value_datatype = value.data_type();
+    // The datatype of json value is determined by its actual data, so we can't simply "cast" it here.
+    if value_datatype.is_json() || value_datatype == *data_type {
+        Ok(value)
+    } else {
         datatypes::types::cast(value, data_type).with_context(|_| InvalidCastSnafu {
             sql_value: sql_val.clone(),
             datatype: data_type,
         })
-    } else {
-        Ok(value)
     }
 }
 

src/common/sql/src/default_constraint.rs

@@ -16,6 +16,7 @@ use common_time::timezone::Timezone;
 use datatypes::prelude::ConcreteDataType;
 use datatypes::schema::ColumnDefaultConstraint;
 use datatypes::schema::constraint::{CURRENT_TIMESTAMP, CURRENT_TIMESTAMP_FN};
+use snafu::ensure;
 use sqlparser::ast::ValueWithSpan;
 pub use sqlparser::ast::{
     BinaryOperator, ColumnDef, ColumnOption, ColumnOptionDef, DataType, Expr, Function,
@@ -37,6 +38,14 @@ pub fn parse_column_default_constraint(
         .iter()
         .find(|o| matches!(o.option, ColumnOption::Default(_)))
     {
+        ensure!(
+            !data_type.is_json(),
+            UnsupportedDefaultValueSnafu {
+                column_name,
+                reason: "json column cannot have a default value",
+            }
+        );
+
         let default_constraint = match &opt.option {
             ColumnOption::Default(Expr::Value(v)) => ColumnDefaultConstraint::Value(
                 sql_value_to_value(column_name, data_type, &v.value, timezone, None, false)?,
@@ -82,7 +91,7 @@ pub fn parse_column_default_constraint(
                 } else {
                     return UnsupportedDefaultValueSnafu {
                         column_name,
-                        expr: *expr.clone(),
+                        reason: format!("expr '{expr}' not supported"),
                     }
                     .fail();
                 }
@@ -90,14 +99,14 @@ pub fn parse_column_default_constraint(
             ColumnOption::Default(others) => {
                 return UnsupportedDefaultValueSnafu {
                     column_name,
-                    expr: others.clone(),
+                    reason: format!("expr '{others}' not supported"),
                 }
                 .fail();
             }
             _ => {
                 return UnsupportedDefaultValueSnafu {
                     column_name,
-                    expr: Expr::Value(SqlValue::Null.into()),
+                    reason: format!("option '{}' not supported", opt.option),
                 }
                 .fail();
             }

src/common/sql/src/error.rs

@@ -55,13 +55,11 @@ pub enum Error {
     },
 
     #[snafu(display(
-        "Unsupported expr in default constraint: {} for column: {}",
-        expr,
-        column_name
+        "Unsupported default constraint for column: '{column_name}', reason: {reason}"
     ))]
     UnsupportedDefaultValue {
         column_name: String,
-        expr: Expr,
+        reason: String,
         #[snafu(implicit)]
         location: Location,
     },