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Support scan Nebula subgraph results (vertex and edge) and slice of struct ptr #346

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merged 9 commits into from
Jan 17, 2025
Merged

Support scan Nebula subgraph results (vertex and edge) and slice of struct ptr #346

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13f2b72
Support scan Nebula vertex and edge
haoxins Jun 26, 2024
c857638
fix: adjust the slice length
haoxins Jun 27, 2024
262f328
support struct ptr in the slice
haoxins Jun 30, 2024
b6d665c
Add tests
haoxins Jul 7, 2024
ada350f
Add more props
haoxins Sep 19, 2024
1b17931
Add supports for slice of struct ptr
haoxins Nov 18, 2024
d870179
check the empty and null value
haoxins Dec 24, 2024
99eb229
no use SetZero
haoxins Dec 24, 2024
4b8a5ab
Merge branch 'master' into feat-nest-struct
Nicole00 Jan 16, 2025
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174 changes: 148 additions & 26 deletions result_set.go
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Original file line number Diff line number Diff line change
Expand Up @@ -335,13 +335,19 @@ func (res ResultSet) Scan(v interface{}) error {
}

// Scan scans the rows into the given value.
func (res ResultSet) scanRow(row *nebula.Row, colNames []string, t reflect.Type) (reflect.Value, error) {
func (res ResultSet) scanRow(row *nebula.Row, colNames []string, rowType reflect.Type) (reflect.Value, error) {
rowVals := row.GetValues()

val := reflect.New(t).Elem()
var result reflect.Value
if rowType.Kind() == reflect.Ptr {
result = reflect.New(rowType.Elem())
} else {
result = reflect.New(rowType).Elem()
}
structVal := reflect.Indirect(result)

for fIdx := 0; fIdx < t.NumField(); fIdx++ {
f := t.Field(fIdx)
for fIdx := 0; fIdx < structVal.Type().NumField(); fIdx++ {
f := structVal.Type().Field(fIdx)
tag := f.Tag.Get("nebula")

if tag == "" {
Expand All @@ -356,31 +362,147 @@ func (res ResultSet) scanRow(row *nebula.Row, colNames []string, t reflect.Type)

rowVal := rowVals[cIdx]

switch f.Type.Kind() {
case reflect.Bool:
val.Field(fIdx).SetBool(rowVal.GetBVal())
case reflect.Int:
val.Field(fIdx).SetInt(rowVal.GetIVal())
case reflect.Int8:
val.Field(fIdx).SetInt(rowVal.GetIVal())
case reflect.Int16:
val.Field(fIdx).SetInt(rowVal.GetIVal())
case reflect.Int32:
val.Field(fIdx).SetInt(rowVal.GetIVal())
case reflect.Int64:
val.Field(fIdx).SetInt(rowVal.GetIVal())
case reflect.Float32:
val.Field(fIdx).SetFloat(rowVal.GetFVal())
case reflect.Float64:
val.Field(fIdx).SetFloat(rowVal.GetFVal())
case reflect.String:
val.Field(fIdx).SetString(string(rowVal.GetSVal()))
default:
return val, errors.New("scan: not support type")
if f.Type.Kind() == reflect.Slice {
list := rowVal.GetLVal()
err := scanListCol(list.Values, structVal.Field(fIdx), f.Type)
if err != nil {
return result, err
}
} else {
err := scanPrimitiveCol(rowVal, structVal.Field(fIdx), f.Type.Kind())
if err != nil {
return result, err
}
}
}

return result, nil
}

func scanListCol(vals []*nebula.Value, listVal reflect.Value, sliceType reflect.Type) error {
switch sliceType.Elem().Kind() {
case reflect.Struct:
var listCol = reflect.MakeSlice(sliceType, 0, len(vals))
for _, val := range vals {
ele := reflect.New(sliceType.Elem()).Elem()
err := scanStructField(val, ele, sliceType.Elem())
if err != nil {
return err
}
listCol = reflect.Append(listCol, ele)
}
listVal.Set(listCol)
case reflect.Ptr:
var listCol = reflect.MakeSlice(sliceType, 0, len(vals))
for _, val := range vals {
ele := reflect.New(sliceType.Elem().Elem())
err := scanStructField(val, reflect.Indirect(ele), sliceType.Elem().Elem())
if err != nil {
return err
}
listCol = reflect.Append(listCol, ele)
}
listVal.Set(listCol)
default:
return errors.New("scan: not support list type")
}

return val, nil
return nil
}

func scanStructField(val *nebula.Value, eleVal reflect.Value, eleType reflect.Type) error {
vertex := val.GetVVal()
if vertex != nil {
tags := vertex.GetTags()
vid := vertex.GetVid()

if len(tags) != 0 {
tag := tags[0]

props := tag.GetProps()
props["_vid"] = vid
tagName := tag.GetName()
props["_tag_name"] = &nebula.Value{SVal: tagName}

err := scanValFromProps(props, eleVal, eleType)
if err != nil {
return err
}
return nil
}
// no tags, continue
}

edge := val.GetEVal()
if edge != nil {
props := edge.GetProps()

src := edge.GetSrc()
dst := edge.GetDst()
name := edge.GetName()
props["_src"] = src
props["_dst"] = dst
props["_name"] = &nebula.Value{SVal: name}

err := scanValFromProps(props, eleVal, eleType)
if err != nil {
return err
}
return nil
}

return nil
}

func scanValFromProps(props map[string]*nebula.Value, val reflect.Value, tpe reflect.Type) error {
for fIdx := 0; fIdx < tpe.NumField(); fIdx++ {
f := tpe.Field(fIdx)
n := f.Tag.Get("nebula")
v, ok := props[n]
if !ok {
continue
}
err := scanPrimitiveCol(v, val.Field(fIdx), f.Type.Kind())
if err != nil {
return err
}
}

return nil
}

func scanPrimitiveCol(rowVal *nebula.Value, val reflect.Value, kind reflect.Kind) error {
w := ValueWrapper{value: rowVal}
if w.IsNull() || w.IsEmpty() {
// SetZero is introduced in go 1.20
// val.SetZero()
return nil
}

switch kind {
case reflect.Bool:
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when rowVal is Null type, how to set value for reflect.Value?

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need to process these two types.
image

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should we just skip to set the value if empty or null? I mean


func scanPrimitiveCol(rowVal *nebula.Value, val reflect.Value, kind reflect.Kind) error {
    if rowVal.IsSetNVal() {
        return nil
    }
    ...
}

But, is there a easy way to do IsEmpty on the type *nebula.Value?

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@haoxins haoxins Dec 23, 2024 •
edited
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May I move the method GetType from ValueWrapper to *Value?

emm, we can't move the method GetType into *nebula.Value

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BTW, what is the situation will output empty or null? I running these codes in my server for months already.

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you means

func scanPrimitiveCol(rowVal *nebula.Value, val reflect.Value, kind reflect.Kind) error {
    w := ValueWrapper{value: rowVal}
    if w.IsNull() || w.IsEmpty() {
        val.SetZero()
        return nil
    }

    ......
}

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Emm, will cause a bit performance cost but not a problem.
And, a bit ugly 😂

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ok, tests passed

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Sorry it's too slow to review it and too late to reply.

Please forgive me for not understanding why it is ugly~ I think that is the logic that must be processed, otherwise this method will not be able to handle null values.

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Please forgive me for not understanding why it is ugly~

Never mind, I found I don't need to copy the logic of IsNull and IsEmpty finally.
Just need to use ValueWrapper.

val.SetBool(rowVal.GetBVal())
case reflect.Int:
val.SetInt(rowVal.GetIVal())
case reflect.Int8:
val.SetInt(rowVal.GetIVal())
case reflect.Int16:
val.SetInt(rowVal.GetIVal())
case reflect.Int32:
val.SetInt(rowVal.GetIVal())
case reflect.Int64:
val.SetInt(rowVal.GetIVal())
case reflect.Float32:
val.SetFloat(rowVal.GetFVal())
case reflect.Float64:
val.SetFloat(rowVal.GetFVal())
case reflect.String:
val.SetString(string(rowVal.GetSVal()))
default:
return errors.New("scan: not support primitive type")
}

return nil
}

// Returns the number of total rows
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