StrAttr cppType error

def Khpd_SeriesType : Khpd_Type<"Series", "series"> {
  let summary = "Khpd Series type.";
  let description = "Khpd series type, takes series name and type <string, Type>.";
  let parameters = (ins StrAttr:$columnName, "mlir::Type":$type);
  let assemblyFormat = "`<` $columnName `:` $type`>`";
}
....:1435:5: error: Missing `cppType` field in Attribute/Type parameter: StrAttr
def StrAttr : StringBasedAttr<CPred<"::llvm::isa<::mlir::StringAttr>($_self)">,
    ^

This is my first time working with llvm or mlir so, this might be a very stupid question.

Weirdly, it is working when I define an operation.

def Khpd_ReadCsvOp : Khpd_Op<"readcsv"> {
    let summary = "Reads the csv file given as input";
    let description = [{ Reads the csv file given as input   }];

    let arguments = (ins StrAttr:$fileName);
    let results = (outs Khpd_DataFrameType:$out);

    let assemblyFormat = [{
        $fileName attr-dict `:` type($out)
    }];
}

Please don’t cross-post. You already asked here I believe: [MLIR] SttrAttr cppType error