/
flattener.go
230 lines (196 loc) · 5.25 KB
/
flattener.go
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package api
import (
"encoding/json"
"github.com/bwmarrin/snowflake"
"github.com/jeremywohl/flatten"
"github.com/oklog/ulid/v2"
"github.com/rs/zerolog/log"
"github.com/scratchdata/scratchdata/pkg/util"
"github.com/tidwall/gjson"
"github.com/tidwall/sjson"
)
type JSONData struct {
Table string
JSON string
}
type Flattener interface {
Flatten(table string, json string) ([]JSONData, error)
}
type VerticalFlattener struct{}
func (e VerticalFlattener) parseMap(obj map[string]interface{}, path []string, useIndices bool) [][]map[string]interface{} {
var result [][]map[string]interface{}
for k, v := range obj {
result = append(result, e.flattenObject(v, append(path, k), useIndices))
}
return result
}
func (e VerticalFlattener) crossProduct(dicts [][]map[string]interface{}) []map[string]interface{} {
if len(dicts) == 0 {
return []map[string]interface{}{{}}
}
var result []map[string]interface{}
for _, lhs := range dicts[0] {
for _, rhs := range e.crossProduct(dicts[1:]) {
result = append(result, e.merge(lhs, rhs))
}
}
return result
}
func (e VerticalFlattener) merge(lhs, rhs map[string]interface{}) map[string]interface{} {
result := make(map[string]interface{})
for k, v := range lhs {
result[k] = v
}
for k, v := range rhs {
result[k] = v
}
return result
}
func (e VerticalFlattener) pathToString(path []string) string {
var result string
for i, p := range path {
if i > 0 {
result += "_"
}
result += p
}
return result
}
func (e VerticalFlattener) flattenObject(obj interface{}, path []string, useIndices bool) []map[string]interface{} {
switch obj := obj.(type) {
case []interface{}:
if len(obj) > 0 {
var result []map[string]interface{}
for i, item := range obj {
newItems := e.flattenObject(item, path, useIndices)
if useIndices {
for _, newItem := range newItems {
newItem["__order_"+e.pathToString(path)] = i
}
}
result = append(result, newItems...)
}
return result
} else {
return []map[string]interface{}{{
e.pathToString(path): nil,
}}
}
case map[string]interface{}:
return e.crossProduct(e.parseMap(obj, path, useIndices))
default:
return []map[string]interface{}{{
e.pathToString(path): obj,
}}
}
}
func (e VerticalFlattener) flattenJSON(obj string, path []string, useIndices bool) ([]string, error) {
var data map[string]interface{}
err := json.Unmarshal([]byte(obj), &data)
if err != nil {
return nil, err
}
flattened := e.flattenObject(data, path, useIndices)
rc := make([]string, 0)
for _, f := range flattened {
b, err := json.Marshal(f)
if err != nil {
log.Err(err).Msg("failed to marshal json")
return nil, err
}
rc = append(rc, string(b))
}
return rc, nil
}
func (e VerticalFlattener) Flatten(table string, json string) ([]JSONData, error) {
documentId := ulid.Make().String()
dataWithDocumentId, err := sjson.Set(json, "___document_id", documentId)
var flattened []string
if err == nil {
flattened, err = e.flattenJSON(dataWithDocumentId, nil, true)
} else {
flattened, err = e.flattenJSON(json, nil, true)
}
if err != nil {
return nil, err
}
rc := make([]JSONData, len(flattened))
for i, data := range flattened {
rc[i].Table = table
rc[i].JSON = data
}
return rc, nil
}
type HorizontalFlattener struct{}
func (h HorizontalFlattener) Flatten(table string, json string) ([]JSONData, error) {
flat, err := flatten.FlattenString(json, "", flatten.UnderscoreStyle)
if err != nil {
return nil, err
}
rc := []JSONData{
{Table: table, JSON: flat},
}
return rc, nil
}
type MultiTableFlattener struct {
snowflake *snowflake.Node
}
func NewMultiTableFlattener() MultiTableFlattener {
snowflake, _ := util.NewSnowflakeGenerator()
return MultiTableFlattener{snowflake: snowflake}
}
func (f MultiTableFlattener) FlattenJSON(table string, data gjson.Result, parent_table string, parent_id int64) ([]JSONData, error) {
output := []JSONData{}
if data.IsObject() {
oid := f.snowflake.Generate().Int64()
rc := map[string]any{
"id": oid,
}
if parent_table != "" {
rc[parent_table+"_id"] = parent_id
}
data.ForEach(func(key, value gjson.Result) bool {
if value.IsArray() || value.IsObject() {
nestedData, err := f.FlattenJSON(key.String(), value, table, oid)
if err != nil {
return false
}
output = append(output, nestedData...)
} else {
rc[key.String()] = value.Value()
}
return true // keep iterating
})
j, err := json.Marshal(rc)
if err != nil {
return []JSONData{}, err
}
output = append(output, JSONData{Table: table, JSON: string(j)})
} else if data.IsArray() {
for _, v := range data.Array() {
nestedData, err := f.FlattenJSON(table, v, parent_table, parent_id)
if err != nil {
return []JSONData{}, err
}
output = append(output, nestedData...)
}
} else {
rc := map[string]any{
"id": f.snowflake.Generate().Int64(),
table: data.Value(),
}
if parent_table != "" {
rc[parent_table+"_id"] = parent_id
}
j, err := json.Marshal(rc)
if err != nil {
return []JSONData{}, err
}
output = append(output, JSONData{Table: table, JSON: string(j)})
}
return output, nil
}
func (f MultiTableFlattener) Flatten(table string, json string) ([]JSONData, error) {
parsed := gjson.Parse(json)
return f.FlattenJSON(table, parsed, "", 0)
}