panic: reflect: call of reflect.Value.Field on zero Value

[folbricht-stripe]

I'm trying to read records into a struct that contains a slice of elements with nested struct-pointers and seeing the following panic:

panic: reflect: call of reflect.Value.Field on zero Value

Below a test I wrote to reproduce the issue. It writes a single record to a parquet file, then tries to read it.

func TestNestedPointer(t *testing.T) {
    type InnerStruct struct {
        InnerField string
    }

    type SliceElement struct {
        Inner *InnerStruct
    }

    type Outer struct {
        Slice []*SliceElement
    }

    in := &Outer{
        Slice: []*SliceElement{
            {
                Inner: &InnerStruct{
                    InnerField: "inner-string",
                },
            },
        },
    }

    tmpDir := t.TempDir()
    parquetFile := filepath.Join(tmpDir, "data.parquet")
    f, err := os.Create(parquetFile)
    if err != nil {
        t.Fatal(err)
    }

    pw := parquet.NewGenericWriter[*Outer](f)
    _, err = pw.Write([]*Outer{in})
    if err != nil {
        t.Fatal(err)
    }

    err = pw.Close()
    if err != nil {
        t.Fatal(err)
    }

    err = f.Close()
    if err != nil {
        t.Fatal(err)
    }

    f, err = os.Open(parquetFile)
    if err != nil {
        t.Fatal(err)
    }
    defer f.Close()

    pr := parquet.NewGenericReader[*Outer](f)

    out := make([]*Outer, 1)
    _, err = pr.Read(out)
    if err != nil {
        t.Fatal(err)
    }

    pr.Close()
}

The code above works as expected if InnerStruct is not a pointer in the slice element.

    type SliceElement struct {
        Inner InnerStruct
    }

Any suggestions on how to fix this? I can't remove the pointers since I'm using generated protobuf messages which always use pointers. The pointers don't appear to be a problem in other places, only if used in a struct that's part of a slice from what I can tell. Any help with this is appreciated.

[kevinburkesegment]

Hi, can you please reopen this ticket at https://github.com/parquet-go/parquet-go; we're trying to move development there.

[folbricht-stripe]

Done, moved to https://github.com/parquet-go/parquet-go/issues/2