Struct Tags

Method parameters are Go structs annotated with vgirpc struct tags. The tag format is:

`vgirpc:"wire_name[,option[,option...]]"`

Options

Option	Effect	Example
(none)	Field mapped by name, default Arrow type	vgirpc:"name"
default=VALUE	Use VALUE when the client omits the parameter	vgirpc:"sep,default=-"
enum	Arrow Dictionary (categorical string)	vgirpc:"status,enum"
int32	Arrow Int32 instead of Int64	vgirpc:"value,int32"
float32	Arrow Float32 instead of Float64	vgirpc:"value,float32"
binary	Serialize an ArrowSerializable as IPC bytes	vgirpc:"point,binary"
struct	Inline Arrow struct column, derived from the field's own struct	vgirpc:"copy_from,struct"

Type Mapping

Go types map to Arrow types as follows:

Go type	Arrow type	Notes
string	Utf8
bool	Boolean
int64	Int64	default for integers
int64 with int32	Int32	via tag option
float64	Float64	default for floats
float64 with float32	Float32	via tag option
string with enum	Dictionary(Utf8)	categorical
ArrowSerializable with binary	Binary	embedded IPC stream
struct with struct	Struct<...>	inline nested column

Nullable Fields

Pointer types become nullable Arrow columns. A nil pointer serializes as an Arrow null:

type Params struct {
    Name  *string `vgirpc:"name"`   // nullable string
    Count *int64  `vgirpc:"count"`  // nullable int
}

Inline Structs

struct makes a field an inline Arrow struct column whose children are derived from the field's own Go struct by these same tag rules, recursively:

type CopyFromContext struct {
    Format         string `vgirpc:"format"`
    FilePath       string `vgirpc:"file_path"`
    ExpectedSchema []byte `vgirpc:"expected_schema"`
}

type BindRequest struct {
    // struct<format: utf8 not null, file_path: utf8 not null,
    //        expected_schema: binary not null>, nullable
    CopyFrom *CopyFromContext `vgirpc:"copy_from,struct"`
}

This is the opposite of binary/ArrowSerializable, which carries a nested value as IPC stream bytes in a binary column. Use struct when the protocol declares the field inline — a peer that validates its parameter contract with Schema.Equal rejects binary where the protocol says struct.

A pointer field is a nullable struct column; a nil pointer serializes as an Arrow null and decodes back to nil, so "absent" stays distinguishable from a present-but-empty struct. Nesting is allowed up to 8 levels (a self-referential type is an error, not a hang). The tag applies to the field's own type only: a slice or map of structs is not supported.

Examples

type ConcatenateParams struct {
    Prefix    string `vgirpc:"prefix"`
    Suffix    string `vgirpc:"suffix"`
    Separator string `vgirpc:"separator,default=-"`
}

type EchoEnumParams struct {
    Status Status `vgirpc:"status,enum"`  // Status is a string type
}

type EchoPointParams struct {
    Point Point `vgirpc:"point,binary"`   // Point implements ArrowSerializable
}