Nested Fields Access on StructArray field not working

[erchirag]

Hi

I have a parquet file with following example data:

{
"a" : "A1",

 "myobjects" : 
  [
          {
                  "name" : "1",
                  "value" : "V"
          },

         {
                   "name" : "2",
                   "value" :  "V2"
         }

  ]

}

When I am trying to access the subfield "Name" none of the following syntax is working for me using latest datafusion package (40.*) and I am getting error as "Nested identifiers not yet supported".

Examples I tried:
SELECT myobjects.element.name FROM my_table;

SELECT myobjects.name FROM my_table;

SELECT myobjects.item.name FROM my_table;

SELECT myobjects["name"] FROM my_table;

From DF I tried
col("myobjects.name")

col("myobjects.item.name")

col("myobjects.element.name");

None of them worked for me, Can someone please help me understand what am I doing wrong ?

[alamb]

What is the type of the column reported?

Maybe

describe my_table

Maybe it is being treated as a MAP or something and we need to add support for it

[erchirag]

The schema of the table is as follows, I don't think it should be treated as MAP

`
``{
"inner" : {
"Schema" : {
"fields" : [
{
"name" : "A",
"data_type" : "Utf8",
"nullable" : false,
"dict_id" : 0,
"dict_is_ordered" : false,
"metadata" : {}
},
{
"name": "myobjects",
"data_type": {
"List": {
"field": {
"name": "element",
"data_type": {
"Struct": [
{
"name": "name",
"data_type": "Utf8",
"nullable": false,
"dict_id": 0,
"dict_is_ordered": false,
"metadata": {}
},
{
"name": "value",
"data_type": "Utf8",
"nullable": false,
"dict_id": 0,
"dict_is_ordered": false,
"metadata": {}
}
}
}
},
"nullable": false,
"dict_id": 0,
"dict_is_ordered": false,
"metadata": {}
}
],
"metadata": {}
},
"field_qualifiers": [
{
"table": "my_table"
},
{
"table": "my_table"
},
{
"table": "my_table"
},
{
"table": "my_table"
},
{
"table": "my_table"
}
],
"functional_dependencies": {
"deps": []
}
}
}

`

[jayzhan211]

You could try ``` your code ``` to wrap your code

[alamb]

I agree this sounds like a bug / limitation to me

What I suggest is filing a ticket with a self-contained reproducer (either as Rust code or preferrably as a datafusion-cli example)

The datafusion CLI is documented here:

https://datafusion.apache.org/user-guide/cli/index.html