Fix columnObject crash with array of variadic dimension elems

src/Columns/ColumnObject.cpp

@@ -154,13 +154,15 @@ FieldInfo getFieldInfo(const Field & field)
 {
     FieldVisitorToScalarType to_scalar_type_visitor;
     applyVisitor(to_scalar_type_visitor, field);
+    FieldVisitorToNumberOfDimensions to_number_dimension_visitor;
 
     return
     {
         to_scalar_type_visitor.getScalarType(),
         to_scalar_type_visitor.haveNulls(),
         to_scalar_type_visitor.needConvertField(),
-        applyVisitor(FieldVisitorToNumberOfDimensions(), field),
+        applyVisitor(to_number_dimension_visitor, field),
+        to_number_dimension_visitor.need_fold_dimension
     };
 }
 

src/Columns/ColumnObject.h

@@ -35,6 +35,10 @@ struct FieldInfo
 
     /// Number of dimension in array. 0 if field is scalar.
     size_t num_dimensions;
+
+    /// If true then this field is an array of variadic dimension field
+    /// and we need to normalize the dimension
+    bool need_fold_dimension;
 };
 
 FieldInfo getFieldInfo(const Field & field);

src/DataTypes/ObjectUtils.cpp

@@ -737,14 +737,31 @@ Field FieldVisitorReplaceScalars::operator()(const Array & x) const
     return res;
 }
 
-size_t FieldVisitorToNumberOfDimensions::operator()(const Array & x) const
+size_t FieldVisitorToNumberOfDimensions::operator()(const Array & x)
 {
     const size_t size = x.size();
     size_t dimensions = 0;
     for (size_t i = 0; i < size; ++i)
-        dimensions = std::max(dimensions, applyVisitor(*this, x[i]));
+    {
+        size_t element_dimensions = applyVisitor(*this, x[i]);
+        if (i > 0 && element_dimensions != dimensions)
+            need_fold_dimension = true;
+        dimensions = std::max(dimensions, element_dimensions);
+    }
 
     return 1 + dimensions;
 }
 
+Field FieldVisitorFoldDimension::operator()(const Array & x) const
+{
+    if (num_dimensions_to_fold == 0)
+        return x;
+    const size_t size = x.size();
+    Array res(size);
+    for (size_t i = 0; i < size; ++i)
+    {
+        res[i] = applyVisitor(FieldVisitorFoldDimension(num_dimensions_to_fold - 1), x[i]);
+    }
+    return res;
+}
 }

src/DataTypes/ObjectUtils.h

@@ -114,10 +114,42 @@ class FieldVisitorReplaceScalars : public StaticVisitor<Field>
 class FieldVisitorToNumberOfDimensions : public StaticVisitor<size_t>
 {
 public:
-    size_t operator()(const Array & x) const;
+    size_t operator()(const Array & x);
 
     template <typename T>
     size_t operator()(const T &) const { return 0; }
+
+    bool need_fold_dimension = false;
+};
+
+/// Fold field (except Null) to the higher dimension, e.g. `1` -- fold 2 --> `[[1]]`
+/// used to normalize dimension of element in an array. e.g [1, [2]] --> [[1], [2]]
+class FieldVisitorFoldDimension : public StaticVisitor<Field>
+{
+public:
+    explicit FieldVisitorFoldDimension(size_t num_dimensions_to_fold_) : num_dimensions_to_fold(num_dimensions_to_fold_) { }
+
+    Field operator()(const Array & x) const;
+
+    Field operator()(const Null & x) const { return x; }
+
+    template <typename T>
+    Field operator()(const T & x) const
+    {
+        if (num_dimensions_to_fold == 0)
+            return x;
+        Array res(1,x);
+        for (size_t i = 1; i < num_dimensions_to_fold; ++i)
+        {
+            Array new_res;
+            new_res.push_back(std::move(res));
+            res = std::move(new_res);
+        }
+        return res;
+    }
+
+private:
+    size_t num_dimensions_to_fold;
 };
 
 /// Receives range of objects, which contains collections

src/DataTypes/Serializations/SerializationObject.cpp

@@ -65,6 +65,8 @@ void SerializationObject<Parser>::deserializeTextImpl(IColumn & column, Reader &
     for (size_t i = 0; i < paths.size(); ++i)
     {
         auto field_info = getFieldInfo(values[i]);
+        if (field_info.need_fold_dimension)
+            values[i] = applyVisitor(FieldVisitorFoldDimension(field_info.num_dimensions), std::move(values[i]));
         if (isNothing(field_info.scalar_type))
             continue;
 

tests/queries/0_stateless/02287_type_object_convert.reference

@@ -12,3 +12,7 @@
 2	(0,2)	Tuple(x Int8, y Int8)
 {"x":1}
 {"x":1}
+{"x":[[1],[1,2]]}
+{"x":[[],[1,2]]}
+{"x":[[],[[1],[2]]]}
+{"x":[[],[[],[2]]]}

tests/queries/0_stateless/02287_type_object_convert.sql

@@ -26,5 +26,9 @@ SELECT id, data, toTypeName(data) FROM t_object_convert2 ORDER BY id;
 DROP TABLE t_object_convert;
 DROP TABLE t_object_convert2;
 
-select CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))');
-select CAST(CAST('{"x" : 1}', 'Object(Nullable(\'json\'))'), 'Object(\'json\')');
+SELECT CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))');
+SELECT CAST(CAST('{"x" : 1}', 'Object(Nullable(\'json\'))'), 'Object(\'json\')');
+SELECT CAST('{"x" : [ 1 , [ 1 , 2] ]}', 'Object(\'json\')');
+SELECT CAST('{"x" : [ {} , [ 1 , 2] ]}', 'Object(\'json\')');
+SELECT CAST('{"x" : [ {} , [ 1 , [2]] ]}', 'Object(\'json\')');
+SELECT CAST('{"x" : [ {} , [ {} , [2]] ]}', 'Object(\'json\')');