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package graphql
import (
"context"
"fmt"
"sync"
"github.com/vektah/gqlparser/ast"
"github.com/vektah/gqlparser/gqlerror"
)
type Resolver func(ctx context.Context) (res interface{}, err error)
type FieldMiddleware func(ctx context.Context, next Resolver) (res interface{}, err error)
type RequestMiddleware func(ctx context.Context, next func(ctx context.Context) []byte) []byte
type RequestContext struct {
RawQuery string
Variables map[string]interface{}
Doc *ast.QueryDocument
// ErrorPresenter will be used to generate the error
// message from errors given to Error().
ErrorPresenter ErrorPresenterFunc
Recover RecoverFunc
ResolverMiddleware FieldMiddleware
DirectiveMiddleware FieldMiddleware
RequestMiddleware RequestMiddleware
errorsMu sync.Mutex
Errors gqlerror.List
}
func DefaultResolverMiddleware(ctx context.Context, next Resolver) (res interface{}, err error) {
return next(ctx)
}
func DefaultDirectiveMiddleware(ctx context.Context, next Resolver) (res interface{}, err error) {
return next(ctx)
}
func DefaultRequestMiddleware(ctx context.Context, next func(ctx context.Context) []byte) []byte {
return next(ctx)
}
func NewRequestContext(doc *ast.QueryDocument, query string, variables map[string]interface{}) *RequestContext {
return &RequestContext{
Doc: doc,
RawQuery: query,
Variables: variables,
ResolverMiddleware: DefaultResolverMiddleware,
DirectiveMiddleware: DefaultDirectiveMiddleware,
RequestMiddleware: DefaultRequestMiddleware,
Recover: DefaultRecover,
ErrorPresenter: DefaultErrorPresenter,
}
}
type key string
const (
request key = "request_context"
resolver key = "resolver_context"
)
func GetRequestContext(ctx context.Context) *RequestContext {
val := ctx.Value(request)
if val == nil {
return nil
}
return val.(*RequestContext)
}
func WithRequestContext(ctx context.Context, rc *RequestContext) context.Context {
return context.WithValue(ctx, request, rc)
}
type ResolverContext struct {
Parent *ResolverContext
// The name of the type this field belongs to
Object string
// These are the args after processing, they can be mutated in middleware to change what the resolver will get.
Args map[string]interface{}
// The raw field
Field CollectedField
// The index of array in path.
Index *int
// The result object of resolver
Result interface{}
}
func (r *ResolverContext) Path() []interface{} {
var path []interface{}
for it := r; it != nil; it = it.Parent {
if it.Index != nil {
path = append(path, *it.Index)
} else if it.Field.Field != nil {
path = append(path, it.Field.Alias)
}
}
// because we are walking up the chain, all the elements are backwards, do an inplace flip.
for i := len(path)/2 - 1; i >= 0; i-- {
opp := len(path) - 1 - i
path[i], path[opp] = path[opp], path[i]
}
return path
}
func GetResolverContext(ctx context.Context) *ResolverContext {
val, _ := ctx.Value(resolver).(*ResolverContext)
return val
}
func WithResolverContext(ctx context.Context, rc *ResolverContext) context.Context {
rc.Parent = GetResolverContext(ctx)
return context.WithValue(ctx, resolver, rc)
}
// This is just a convenient wrapper method for CollectFields
func CollectFieldsCtx(ctx context.Context, satisfies []string) []CollectedField {
resctx := GetResolverContext(ctx)
return CollectFields(ctx, resctx.Field.Selections, satisfies)
}
// Errorf sends an error string to the client, passing it through the formatter.
func (c *RequestContext) Errorf(ctx context.Context, format string, args ...interface{}) {
c.errorsMu.Lock()
defer c.errorsMu.Unlock()
c.Errors = append(c.Errors, c.ErrorPresenter(ctx, fmt.Errorf(format, args...)))
}
// Error sends an error to the client, passing it through the formatter.
func (c *RequestContext) Error(ctx context.Context, err error) {
c.errorsMu.Lock()
defer c.errorsMu.Unlock()
c.Errors = append(c.Errors, c.ErrorPresenter(ctx, err))
}
// HasError returns true if the current field has already errored
func (c *RequestContext) HasError(rctx *ResolverContext) bool {
c.errorsMu.Lock()
defer c.errorsMu.Unlock()
path := rctx.Path()
for _, err := range c.Errors {
if equalPath(err.Path, path) {
return true
}
}
return false
}
func equalPath(a []interface{}, b []interface{}) bool {
if len(a) != len(b) {
return false
}
for i := 0; i < len(a); i++ {
if a[i] != b[i] {
return false
}
}
return true
}
// AddError is a convenience method for adding an error to the current response
func AddError(ctx context.Context, err error) {
GetRequestContext(ctx).Error(ctx, err)
}
// AddErrorf is a convenience method for adding an error to the current response
func AddErrorf(ctx context.Context, format string, args ...interface{}) {
GetRequestContext(ctx).Errorf(ctx, format, args...)
}
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