feat: Add transformation option to the field configuration

pkg/engine/plan/plan.go

@@ -9,6 +9,9 @@ import (
  "regexp"
  "strings"
 
+ "github.com/jensneuse/pipeline/pkg/pipe"
+ "github.com/jensneuse/pipeline/pkg/step"
+
  "github.com/wundergraph/graphql-go-tools/pkg/ast"
  "github.com/wundergraph/graphql-go-tools/pkg/astimport"
  "github.com/wundergraph/graphql-go-tools/pkg/astvisitor"
@@ -122,6 +125,8 @@ type FieldConfiguration struct {
  // e.g. {"response":"{\"foo\":\"bar\"}"} will be returned as {"foo":"bar"} when path is "response"
  // This way, it is possible to resolve a JSON string as part of the response without extra String encoding of the JSON
  UnescapeResponseJson bool
+ // A Template representing the JSON Transformation
+ Transformation string
 }
 
 type ArgumentsConfigurations []ArgumentConfiguration
@@ -568,12 +573,13 @@ func (v *Visitor) EnterField(ref int) {
  }
 
  path := v.resolveFieldPath(ref)
+ transformation := v.resolveTransformation(ref)
  fieldDefinitionType := v.Definition.FieldDefinitionType(fieldDefinition)
  bufferID, hasBuffer := v.fieldBuffers[ref]
 
  v.currentField = &resolve.Field{
  Name: fieldAliasOrName,
- Value: v.resolveFieldValue(ref, fieldDefinitionType, true, path),
+ Value: v.resolveFieldValue(ref, fieldDefinitionType, true, path, transformation),
  HasBuffer: hasBuffer,
  BufferID: bufferID,
  OnTypeNames: v.resolveOnTypeNames(),
@@ -708,7 +714,7 @@ func (v *Visitor) skipField(ref int) bool {
  return false
 }
 
-func (v *Visitor) resolveFieldValue(fieldRef, typeRef int, nullable bool, path []string) resolve.Node {
+func (v *Visitor) resolveFieldValue(fieldRef, typeRef int, nullable bool, path []string, transformation *pipe.Pipeline) resolve.Node {
  ofType := v.Definition.Types[typeRef].OfType
 
  fieldName := v.Operation.FieldNameString(fieldRef)
@@ -721,14 +727,21 @@ func (v *Visitor) resolveFieldValue(fieldRef, typeRef int, nullable bool, path [
 
  switch v.Definition.Types[typeRef].TypeKind {
  case ast.TypeKindNonNull:
- return v.resolveFieldValue(fieldRef, ofType, false, path)
+ return v.resolveFieldValue(fieldRef, ofType, false, path, transformation)
  case ast.TypeKindList:
- listItem := v.resolveFieldValue(fieldRef, ofType, true, nil)
- return &resolve.Array{
+ listItem := v.resolveFieldValue(fieldRef, ofType, true, nil, transformation)
+ array := &resolve.Array{
  Nullable: nullable,
  Path: path,
  Item: listItem,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: array,
+ Pipeline: transformation,
+ }
+ }
+ return array
  case ast.TypeKindNamed:
  typeName := v.Definition.ResolveTypeNameString(typeRef)
  customResolve, ok := v.Config.CustomResolveMap[typeName]
@@ -747,50 +760,99 @@ func (v *Visitor) resolveFieldValue(fieldRef, typeRef int, nullable bool, path [
  fieldExport := v.resolveFieldExport(fieldRef)
  switch typeName {
  case "String":
- return &resolve.String{
+ value := &resolve.String{
  Path: path,
  Nullable: nullable,
  Export: fieldExport,
  UnescapeResponseJson: unescapeResponseJson,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  case "Boolean":
- return &resolve.Boolean{
+ value := &resolve.Boolean{
  Path: path,
  Nullable: nullable,
  Export: fieldExport,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  case "Int":
- return &resolve.Integer{
+ value := &resolve.Integer{
  Path: path,
  Nullable: nullable,
  Export: fieldExport,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  case "Float":
- return &resolve.Float{
+ value := &resolve.Float{
  Path: path,
  Nullable: nullable,
  Export: fieldExport,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  case "BigInt":
- return &resolve.BigInt{
+ value := &resolve.BigInt{
  Path: path,
  Nullable: nullable,
  Export: fieldExport,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  default:
- return &resolve.String{
+ value := &resolve.String{
  Path: path,
  Nullable: nullable,
  Export: fieldExport,
  UnescapeResponseJson: unescapeResponseJson,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  }
  case ast.NodeKindEnumTypeDefinition:
- return &resolve.String{
+ value := &resolve.String{
  Path: path,
  Nullable: nullable,
  UnescapeResponseJson: unescapeResponseJson,
  }
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  case ast.NodeKindObjectTypeDefinition, ast.NodeKindInterfaceTypeDefinition, ast.NodeKindUnionTypeDefinition:
  object := &resolve.Object{
  Nullable: nullable,
@@ -805,12 +867,32 @@ func (v *Visitor) resolveFieldValue(fieldRef, typeRef int, nullable bool, path [
  fields: &object.Fields,
  })
  })
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: object,
+ Pipeline: transformation,
+ }
+ }
  return object
  default:
- return &resolve.Null{}
+ value := &resolve.Null{}
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  }
  default:
- return &resolve.Null{}
+ value := &resolve.Null{}
+ if transformation != nil {
+ return &resolve.Transformation{
+ InnerValue: value,
+ Pipeline: transformation,
+ }
+ }
+ return value
  }
 }
 
@@ -975,6 +1057,25 @@ func (v *Visitor) resolveFieldPath(ref int) []string {
  return []string{fieldName}
 }
 
+func (v *Visitor) resolveTransformation(ref int) *pipe.Pipeline {
+ typeName := v.Walker.EnclosingTypeDefinition.NameString(v.Definition)
+ fieldName := v.Operation.FieldNameUnsafeString(ref)
+
+ for i := range v.Config.Fields {
+ if v.Config.Fields[i].TypeName == typeName && v.Config.Fields[i].FieldName == fieldName {
+ if len(v.Config.Fields[i].Transformation) > 0 {
+ step, err := step.NewJSON(v.Config.Fields[i].Transformation)
+ if err == nil {
+ return &pipe.Pipeline{Steps: []pipe.Step{step}}
+ }
+
+ }
+ return nil
+ }
+ }
+ return nil
+}
+
 func (v *Visitor) EnterDocument(operation, definition *ast.Document) {
  v.Operation, v.Definition = operation, definition
  v.fieldConfigs = map[int]*FieldConfiguration{}