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inputtemplate.go
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inputtemplate.go
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package resolve
import (
"bytes"
"context"
"errors"
"fmt"
"github.com/buger/jsonparser"
"github.com/wundergraph/graphql-go-tools/v2/pkg/engine/datasource/httpclient"
"github.com/wundergraph/graphql-go-tools/v2/pkg/lexer/literal"
)
type SegmentType int
const (
StaticSegmentType SegmentType = iota + 1
VariableSegmentType
)
type TemplateSegment struct {
SegmentType SegmentType
Data []byte
VariableKind VariableKind
VariableSourcePath []string
Renderer VariableRenderer
Segments []TemplateSegment
}
type InputTemplate struct {
Segments []TemplateSegment
// SetTemplateOutputToNullOnVariableNull will safely return "null" if one of the template variables renders to null
// This is the case, e.g. when using batching and one sibling is null, resulting in a null value for one batch item
// Returning null in this case tells the batch implementation to skip this item
SetTemplateOutputToNullOnVariableNull bool
}
func SetInputUndefinedVariables(preparedInput *bytes.Buffer, undefinedVariables []string) error {
if len(undefinedVariables) > 0 {
output, err := httpclient.SetUndefinedVariables(preparedInput.Bytes(), undefinedVariables)
if err != nil {
return err
}
preparedInput.Reset()
_, _ = preparedInput.Write(output)
}
return nil
}
var setTemplateOutputNull = errors.New("set to null")
func (i *InputTemplate) Render(ctx *Context, data []byte, preparedInput *bytes.Buffer) error {
var undefinedVariables []string
if err := i.renderSegments(ctx, data, i.Segments, preparedInput, &undefinedVariables); err != nil {
return err
}
return SetInputUndefinedVariables(preparedInput, undefinedVariables)
}
func (i *InputTemplate) RenderAndCollectUndefinedVariables(ctx *Context, data []byte, preparedInput *bytes.Buffer, undefinedVariables *[]string) (err error) {
err = i.renderSegments(ctx, data, i.Segments, preparedInput, undefinedVariables)
return
}
func (i *InputTemplate) renderSegments(ctx *Context, data []byte, segments []TemplateSegment, preparedInput *bytes.Buffer, undefinedVariables *[]string) (err error) {
for _, segment := range segments {
switch segment.SegmentType {
case StaticSegmentType:
_, _ = preparedInput.Write(segment.Data)
case VariableSegmentType:
switch segment.VariableKind {
case ObjectVariableKind:
err = i.renderObjectVariable(ctx.Context(), data, segment, preparedInput)
case ContextVariableKind:
var undefined bool
undefined, err = i.renderContextVariable(ctx, segment, preparedInput)
if undefined {
*undefinedVariables = append(*undefinedVariables, segment.VariableSourcePath[0])
}
case ResolvableObjectVariableKind:
err = i.renderResolvableObjectVariable(ctx.Context(), data, segment, preparedInput)
case HeaderVariableKind:
err = i.renderHeaderVariable(ctx, segment.VariableSourcePath, preparedInput)
default:
err = fmt.Errorf("InputTemplate.Render: cannot resolve variable of kind: %d", segment.VariableKind)
}
if err != nil {
if errors.Is(err, setTemplateOutputNull) {
preparedInput.Reset()
_, _ = preparedInput.Write(literal.NULL)
return nil
}
return err
}
}
}
return err
}
func (i *InputTemplate) renderObjectVariable(ctx context.Context, variables []byte, segment TemplateSegment, preparedInput *bytes.Buffer) error {
value, valueType, offset, err := jsonparser.Get(variables, segment.VariableSourcePath...)
if err != nil || valueType == jsonparser.Null {
if i.SetTemplateOutputToNullOnVariableNull {
return setTemplateOutputNull
}
_, _ = preparedInput.Write(literal.NULL)
return nil
}
if valueType == jsonparser.String {
value = variables[offset-len(value)-2 : offset]
switch segment.Renderer.GetKind() {
case VariableRendererKindPlain, VariableRendererKindPlanWithValidation:
if plainRenderer, ok := (segment.Renderer).(*PlainVariableRenderer); ok {
plainRenderer.mu.Lock()
plainRenderer.rootValueType.Value = valueType
plainRenderer.mu.Unlock()
}
}
}
return segment.Renderer.RenderVariable(ctx, value, preparedInput)
}
func (i *InputTemplate) renderResolvableObjectVariable(ctx context.Context, objectData []byte, segment TemplateSegment, preparedInput *bytes.Buffer) error {
return segment.Renderer.RenderVariable(ctx, objectData, preparedInput)
}
func (i *InputTemplate) renderContextVariable(ctx *Context, segment TemplateSegment, preparedInput *bytes.Buffer) (variableWasUndefined bool, err error) {
value, valueType, offset, err := jsonparser.Get(ctx.Variables, segment.VariableSourcePath...)
if err != nil || valueType == jsonparser.Null {
if err == jsonparser.KeyPathNotFoundError {
_, _ = preparedInput.Write(literal.NULL)
return true, nil
}
return false, segment.Renderer.RenderVariable(ctx.Context(), value, preparedInput)
}
if valueType == jsonparser.String {
value = ctx.Variables[offset-len(value)-2 : offset]
switch segment.Renderer.GetKind() {
case VariableRendererKindPlain, VariableRendererKindPlanWithValidation:
if plainRenderer, ok := (segment.Renderer).(*PlainVariableRenderer); ok {
plainRenderer.rootValueType.Value = valueType
}
}
}
return false, segment.Renderer.RenderVariable(ctx.Context(), value, preparedInput)
}
func (i *InputTemplate) renderHeaderVariable(ctx *Context, path []string, preparedInput *bytes.Buffer) error {
if len(path) != 1 {
return errHeaderPathInvalid
}
value := ctx.Request.Header.Values(path[0])
if len(value) == 0 {
return nil
}
if len(value) == 1 {
preparedInput.WriteString(value[0])
return nil
}
for j := range value {
if j != 0 {
_, _ = preparedInput.Write(literal.COMMA)
}
preparedInput.WriteString(value[j])
}
return nil
}