How to write with nested struct

[yorsita]

Hi Team, I'm new to this package and sorry to bother. I was trying to write a series of data with nested struct like

type People struct {
    Name string
    Age int
}

type Nested struct {
    P []People
    F string
    GF string
}

and here are two issues I met:

1. how write with nested struct ? I tried to write with the following code but failed with "read error: EOF":

   func main() {
   type People struct {
       Name string
       Age  int
   }
   
   type Nested struct {
       P  []People
       F  string
       GF string
   }
   row1 := Nested{P: []People{
       {
           Name: "Bob",
           Age:  10,
       }}}
   ods := []Nested{
       row1,
   }
   buf := new(bytes.Buffer)
   w := parquet.NewGenericWriter[Nested](buf)
   _, err := w.Write(ods)
   if err != nil {
       log.Fatal("write error: ", err)
   }
   w.Close()
   
   file := bytes.NewReader(buf.Bytes())
   rows, err := parquet.Read[Nested](file, file.Size())
   if err != nil {
       log.Fatal("read error: ", err)
   }
   
   for _, row := range rows {
       fmt.Printf("%q\n", row)
   }
   }

2. can segmentio/parquet-go write partial fields to parquet according to a new struct? It was like I have stored a slice of data with struct

   type Nested struct {
   P []People
   F string
   GF string
   }

   and when I write to parquet I just want to store

   type Nested struct {
   P []People
   F string
   // GF string         ignore GF field
   }

sorry to bother and wondering if there is a example doc ? Thank you so much

[achille-roussel]

Hello @yorsita

how write with nested struct ? I tried to write with the following code but failed with "read error: EOF":

I submitted this patch to address the issue: https://github.com/segmentio/parquet-go/pull/378

can segmentio/parquet-go write partial fields to parquet according to a new struct? It was like I have stored a slice of data with struct

You should be able to use struct tags to achieve this:

type Nested struct {
    P []People
    F string
    GF string `parquet:"-"` // omit the field
}