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dynamic_frame.go
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dynamic_frame.go
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package sqlutil
import (
"database/sql"
"time"
"github.com/grafana/grafana-plugin-sdk-go/data"
"github.com/grafana/grafana-plugin-sdk-go/data/converters"
)
const STRING = "string"
func isDynamic(converters []Converter) bool {
for _, conv := range converters {
if conv.Dynamic {
return true
}
}
return false
}
func findDataTypes(rows Rows, rowLimit int64, types []*sql.ColumnType) ([]Field, [][]interface{}, error) {
var i int64
fields := make(map[int]Field)
var returnData [][]interface{}
for rows.Next() {
if i == rowLimit {
break
}
row := make([]interface{}, len(types))
for i := range row {
row[i] = new(interface{})
}
err := rows.Scan(row)
if err != nil {
return nil, nil, err
}
returnData = append(returnData, row)
if len(fields) == len(types) {
// found all data types. keep looping to load all the return data
continue
}
for colIdx, col := range row {
val := *col.(*interface{})
var field Field
colType := types[colIdx]
switch val.(type) {
case time.Time, *time.Time:
field.converter = &TimeToNullableTime
field.kind = "time"
field.name = colType.Name()
case float64, float32, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
field.converter = &IntOrFloatToNullableFloat64
field.kind = "float64"
field.name = colType.Name()
case string:
field.converter = &converters.AnyToNullableString
field.kind = STRING
field.name = colType.Name()
case []uint8:
field.converter = &converters.Uint8ArrayToNullableString
field.kind = STRING
field.name = colType.Name()
case nil:
continue
default:
field.converter = &converters.AnyToNullableString
field.kind = STRING
field.name = colType.Name()
}
fields[colIdx] = field
}
i++
}
fieldList := []Field{}
for colIdx, col := range types {
field, ok := fields[colIdx]
field.name = col.Name()
if !ok {
field = Field{
converter: &converters.AnyToNullableString,
kind: "string",
name: col.Name(),
}
}
fieldList = append(fieldList, field)
}
return fieldList, returnData, nil
}
func frameDynamic(rows Rows, rowLimit int64, types []*sql.ColumnType, converters []Converter) (*data.Frame, error) {
// find data type(s) from the data
fields, rawRows, err := findDataTypes(rows, rowLimit, types)
if err != nil {
return nil, err
}
// if a converter is defined by column name, override data type that was found
fields = overrideConverter(fields, converters)
frameFields := make(data.Fields, len(fields))
for i, f := range fields {
frameFields[i] = data.NewFieldFromFieldType(f.converter.OutputFieldType, 0)
frameFields[i].Name = f.name
}
frame := data.NewFrame("", frameFields...)
for _, row := range rawRows {
var rowData []interface{}
for colIdx, col := range row {
field := fields[colIdx]
val := col
ptr, ok := col.(*interface{})
if ok {
val = *ptr
}
val, err := field.converter.Converter(val)
if err != nil {
return nil, err
}
rowData = append(rowData, val)
}
frame.AppendRow(rowData...)
}
return frame, nil
}
// if a converter is defined by column name, override data type that was found
func overrideConverter(fields []Field, converters []Converter) []Field {
var overrides []Field
for _, field := range fields {
converter := field.converter
for _, c := range converters {
if c.InputColumnName == field.name {
var conv = data.FieldConverter{
OutputFieldType: c.FrameConverter.FieldType,
Converter: c.FrameConverter.ConverterFunc,
}
converter = &conv
break
}
}
override := Field{
name: field.name,
converter: converter,
kind: field.kind,
}
overrides = append(overrides, override)
}
return overrides
}
type Field struct {
name string
converter *data.FieldConverter
kind string
}
type RowIterator interface {
Next() bool
Scan(dest ...interface{}) error
}
type Rows struct {
itr RowIterator
}
func (rs Rows) Next() bool {
return rs.itr.Next()
}
func (rs Rows) Scan(dest []interface{}) error {
return rs.itr.Scan(dest...)
}