forked from cayleygraph/cayley
/
graphql.go
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/
graphql.go
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package graphql
import (
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"strconv"
"strings"
"unicode"
"github.com/dennwc/graphql/language/ast"
"github.com/dennwc/graphql/language/lexer"
"github.com/dennwc/graphql/language/parser"
"github.com/cayleygraph/cayley/graph"
"github.com/cayleygraph/cayley/graph/path"
"github.com/cayleygraph/cayley/quad"
"github.com/cayleygraph/cayley/query"
)
const Name = "graphql"
// GraphQL charset: [_A-Za-z][_0-9A-Za-z]*
// (https://facebook.github.io/graphql/#sec-Names)
// IRI charset: [^#x00-#x20<>"{}|^`\]
// (https://www.w3.org/TR/turtle/#grammar-production-IRIREF)
func allowedNameRune(r rune) bool {
// will include <> in the IRI value
return r > 0x20 && !strings.ContainsRune("\"{}()|^`", r) && !unicode.IsSpace(r)
}
func init() {
lexer.AllowNameRunes = allowedNameRune
query.RegisterLanguage(query.Language{
Name: Name,
Session: func(qs graph.QuadStore) query.Session {
return NewSession(qs)
},
REPL: func(qs graph.QuadStore) query.REPLSession {
return NewSession(qs)
},
HTTPError: httpError,
HTTPQuery: httpQuery,
})
}
func NewSession(qs graph.QuadStore) *Session {
return &Session{qs: qs}
}
type resultMap map[string]interface{}
func (resultMap) Err() error { return nil }
func (m resultMap) Result() interface{} { return map[string]interface{}(m) }
type Session struct {
qs graph.QuadStore
}
func (s *Session) Execute(ctx context.Context, qu string, out chan query.Result, limit int) {
defer close(out)
q, err := Parse(strings.NewReader(qu))
if err != nil {
select {
case out <- query.ErrorResult(err):
case <-ctx.Done():
}
return
}
m, err := q.Execute(ctx, s.qs)
var r query.Result
if err != nil {
r = query.ErrorResult(err)
} else {
r = resultMap(m)
}
select {
case out <- r:
case <-ctx.Done():
}
}
func (s *Session) FormatREPL(result query.Result) string {
data, _ := json.MarshalIndent(result, "", " ")
return string(data)
}
// Configurable keywords and special field names.
var (
ValueKey = "id"
LimitKey = "first"
SkipKey = "offset"
AnyKey = "*"
)
type Query struct {
fields []field
}
type has struct {
Via quad.IRI
Rev bool
Values []quad.Value
Labels []quad.Value
}
type field struct {
Via quad.IRI
Alias string
Rev bool
Opt bool
Labels []quad.Value
Has []has
Fields []field
AllFields bool // fetch all fields
UnNest bool // all fields will be saved to parent object
}
func (f field) isSave() bool { return len(f.Has)+len(f.Fields) == 0 && !f.AllFields }
type object struct {
id graph.Value
fields map[string]interface{}
}
func buildIterator(qs graph.QuadStore, p *path.Path) graph.Iterator {
it, _ := p.BuildIterator().Optimize()
it, _ = qs.OptimizeIterator(it)
return it
}
func iterateObject(ctx context.Context, qs graph.QuadStore, f *field, p *path.Path) (out []map[string]interface{}, _ error) {
if len(f.Labels) != 0 {
p = p.LabelContext(f.Labels)
} else {
p = p.LabelContext()
}
var (
limit = -1
skip = 0
)
for _, h := range f.Has {
switch h.Via {
case quad.IRI(ValueKey): // special key - "id"
p = p.Is(h.Values...)
case quad.IRI(LimitKey), quad.IRI(SkipKey): // limit and skip
if len(h.Values) != 1 {
return nil, fmt.Errorf("unexpected arguments: %v (%d)", h.Values, len(h.Values))
}
n, ok := h.Values[0].(quad.Int)
if !ok {
return nil, fmt.Errorf("unexpected value type for %v: %T", string(h.Via), h.Values[0])
}
if h.Via == quad.IRI(LimitKey) {
limit = int(n)
} else {
skip = int(n)
if skip < 0 {
skip = 0
}
}
default: // everything else - Has constraint
if len(h.Labels) != 0 {
p = p.LabelContext(h.Labels)
}
if h.Rev {
p = p.HasReverse(h.Via, h.Values...)
} else {
p = p.Has(h.Via, h.Values...)
}
if len(h.Labels) != 0 {
p = p.LabelContext()
}
}
}
tail := func() {
if skip > 0 {
p = p.Skip(int64(skip))
}
if limit >= 0 {
p = p.Limit(int64(limit))
}
}
if f.AllFields {
tail()
it := buildIterator(qs, p)
defer it.Close()
// we don't care about alternative paths to nodes here, so we will not call NextPath
// and we haven't tagged anything, so we will not call TagResult either
for i := 0; limit < 0 || i < limit; i++ {
select {
case <-ctx.Done():
return out, ctx.Err()
default:
}
if !it.Next(ctx) {
break
}
nv := it.Result()
obj := make(map[string]interface{})
obj[ValueKey] = qs.NameOf(nv)
func() {
sit := qs.QuadIterator(quad.Subject, nv)
defer sit.Close()
for sit.Next(ctx) {
q := qs.Quad(sit.Result())
if p, ok := q.Predicate.(quad.IRI); ok {
obj[string(p)] = q.Object
} else {
obj[quad.ToString(q.Predicate)] = q.Object
}
}
}()
out = append(out, obj)
}
return out, it.Err()
}
unnest := make(map[string]bool)
for _, f2 := range f.Fields {
if f2.UnNest {
unnest[f2.Alias] = true
}
if !f2.isSave() {
continue
}
if f2.Via == quad.IRI(ValueKey) {
p = p.Tag(f2.Alias)
continue
}
if len(f2.Labels) != 0 {
p = p.LabelContext(f2.Labels)
}
if f2.Opt {
if f2.Rev {
p = p.SaveOptionalReverse(f2.Via, f2.Alias)
} else {
p = p.SaveOptional(f2.Via, f2.Alias)
}
} else {
if f2.Rev {
p = p.SaveReverse(f2.Via, f2.Alias)
} else {
p = p.Save(f2.Via, f2.Alias)
}
}
if len(f2.Labels) != 0 {
p = p.LabelContext()
}
}
tail()
// first, collect result node ids and any tags associated with it (flat values)
it := buildIterator(qs, p)
defer it.Close()
var results []object
for i := 0; limit < 0 || i < limit; i++ {
select {
case <-ctx.Done():
return out, ctx.Err()
default:
}
if !it.Next(ctx) {
break
}
fields := make(map[string][]graph.Value)
tags := make(map[string]graph.Value)
it.TagResults(tags)
for k, v := range tags {
fields[k] = []graph.Value{v}
}
for it.NextPath(ctx) {
select {
case <-ctx.Done():
return out, ctx.Err()
default:
}
tags = make(map[string]graph.Value)
it.TagResults(tags)
dedup:
for k, v := range tags {
vals := fields[k]
for _, v2 := range vals {
if graph.ToKey(v) == graph.ToKey(v2) {
continue dedup
}
}
fields[k] = append(vals, v)
}
}
obj := object{id: it.Result()}
if len(fields) > 0 {
obj.fields = make(map[string]interface{}, len(fields))
for k, arr := range fields {
vals, err := graph.ValuesOf(ctx, qs, arr)
if err != nil {
return nil, err
}
if len(vals) == 1 {
obj.fields[k] = vals[0]
} else {
obj.fields[k] = vals
}
}
}
results = append(results, obj)
}
if err := it.Err(); err != nil {
return out, err
}
// next, load complex objects inside fields
for _, r := range results {
obj := r.fields
if obj == nil {
obj = make(map[string]interface{})
}
for _, f2 := range f.Fields {
if f2.isSave() {
continue // skip flat values
}
// start from saved id for a field node
p2 := path.StartPathNodes(qs, r.id)
if len(f2.Labels) != 0 {
p2 = p2.LabelContext(f2.Labels)
}
if f2.Rev {
p2 = p2.In(f2.Via)
} else {
p2 = p2.Out(f2.Via)
}
if len(f2.Labels) != 0 {
p2 = p2.LabelContext()
}
arr, err := iterateObject(ctx, qs, &f2, p2)
if err != nil {
return out, err
}
if f2.UnNest {
if len(arr) > 1 {
return nil, fmt.Errorf("cannot unnest more than one object on %q; use (%s: 1) to force",
f2.Alias, LimitKey)
}
for k, v := range arr[0] {
obj[k] = v
}
} else {
var v interface{}
if len(arr) == 1 {
v = arr[0]
} else if len(arr) > 1 {
v = arr
}
obj[f2.Alias] = v
}
}
out = append(out, obj)
}
return out, nil
}
func (q *Query) Execute(ctx context.Context, qs graph.QuadStore) (map[string]interface{}, error) {
out := make(map[string]interface{})
for _, f := range q.fields {
arr, err := iterateObject(ctx, qs, &f, path.StartPath(qs))
if err != nil {
return out, err
}
var v interface{}
if len(arr) == 1 {
v = arr[0]
} else if len(arr) > 1 {
v = arr
}
out[f.Alias] = v
}
return out, nil
}
func Parse(r io.Reader) (*Query, error) {
data, err := ioutil.ReadAll(r)
if err != nil {
return nil, err
}
doc, err := parser.Parse(parser.ParseParams{Source: string(data)})
if err != nil {
return nil, err
}
if len(doc.Definitions) != 1 {
return nil, fmt.Errorf("unsupported query type")
}
def, ok := doc.Definitions[0].(*ast.OperationDefinition)
if !ok {
return nil, fmt.Errorf("unsupported query type: %T", doc.Definitions[0])
} else if def.Operation != "query" {
return nil, fmt.Errorf("unsupported operation: %s", def.Operation)
}
fields, all, err := setToFields(def.SelectionSet, nil)
if err != nil {
return nil, err
} else if all {
return nil, fmt.Errorf("expand all is not supported at top level")
}
return &Query{fields: fields}, nil
}
func setToFields(set *ast.SelectionSet, labels []quad.Value) (out []field, all bool, _ error) {
if set == nil {
return
}
for _, s := range set.Selections {
switch sel := s.(type) {
case *ast.Field:
fld, err := convField(sel, labels)
if err != nil {
return nil, false, err
}
if fld.Via == quad.IRI(AnyKey) {
if len(set.Selections) != 1 {
return nil, false, fmt.Errorf("expand all cannot be used with other fields")
} else if len(fld.Has) != 0 || len(fld.Fields) != 0 {
return nil, false, fmt.Errorf("filters inside expand all are not supported")
}
return nil, true, nil
}
out = append(out, fld)
default:
return nil, false, fmt.Errorf("unknown selection type: %T", s)
}
}
return
}
func stringToVia(s string) (_ quad.IRI, rev bool) {
if len(s) > 0 && s[0] == '~' {
rev = true
s = s[1:]
}
if len(s) > 2 && s[0] == '<' && s[len(s)-1] == '>' {
s = s[1 : len(s)-1]
}
return quad.IRI(s), rev
}
func argsToHas(dst []has, args []*ast.Argument, rev bool, labels []quad.Value) (out []has, err error) {
out = dst
for _, arg := range args {
var vals []quad.Value
vals, err = convValue(arg.Value)
if err != nil {
return
}
h := has{Values: vals, Labels: labels}
h.Via, h.Rev = stringToVia(arg.Name.Value)
h.Rev = h.Rev != rev
out = append(out, h)
}
return
}
func convField(fld *ast.Field, labels []quad.Value) (out field, err error) {
out.Labels = labels
name := fld.Name.Value
if fld.Alias != nil && fld.Alias.Value != "" {
out.Alias = fld.Alias.Value
} else {
out.Alias = name
}
out.Via, out.Rev = stringToVia(name)
// first check for "label" directive - it will affect all traversals
for _, d := range fld.Directives {
if d.Name == nil {
continue
}
switch d.Name.Value {
case "label":
if len(d.Arguments) == 0 {
out.Labels = nil
} else if len(d.Arguments) > 1 {
return out, fmt.Errorf("label directive should have 0 or 1 argument")
} else if a := d.Arguments[0]; a.Name == nil || a.Name.Value != "v" {
return out, fmt.Errorf("label directive should have 'v' argument")
} else {
vals, err := convValue(a.Value)
if err != nil {
return out, fmt.Errorf("error parsing label: %v", err)
}
out.Labels = vals
}
}
}
for _, d := range fld.Directives {
if d.Name == nil {
continue
}
switch d.Name.Value {
case "rev", "reverse":
if len(d.Arguments) == 0 {
out.Rev = out.Rev != true
} else {
out.Has, err = argsToHas(out.Has, d.Arguments, true, out.Labels)
if err != nil {
return
}
}
case "opt", "optional":
out.Opt = true
case "label":
// already processed
case "unnest":
out.UnNest = true
default:
return out, fmt.Errorf("unknown directive: %q", d.Name.Value)
}
}
out.Fields, out.AllFields, err = setToFields(fld.SelectionSet, out.Labels)
if err != nil {
return
}
out.Has, err = argsToHas(out.Has, fld.Arguments, false, out.Labels)
if err != nil {
return
}
return
}
func convValue(v ast.Value) (out []quad.Value, _ error) {
switch v := v.(type) {
case *ast.EnumValue:
s := v.Value
if len(s) > 2 && s[0] == '<' && s[len(s)-1] == '>' {
s = s[1 : len(s)-1]
}
if len(s) > 2 && s[0] == '_' && s[1] == ':' {
return []quad.Value{quad.BNode(s[2:])}, nil
}
return []quad.Value{quad.IRI(s)}, nil
case *ast.StringValue:
return []quad.Value{quad.StringToValue(v.Value)}, nil
case *ast.IntValue:
pv, _ := strconv.Atoi(v.Value)
return []quad.Value{quad.Int(pv)}, nil
case *ast.FloatValue:
pv, _ := strconv.ParseFloat(v.Value, 64)
return []quad.Value{quad.Float(pv)}, nil
case *ast.BooleanValue:
return []quad.Value{quad.Bool(v.Value)}, nil
case *ast.ListValue:
for _, sv := range v.Values {
cv, err := convValue(sv)
if err != nil {
return nil, err
} else if len(cv) != 1 {
return nil, fmt.Errorf("unexpected value array in list: %v (%d)", cv, len(cv))
}
out = append(out, cv[0])
}
return
default:
return nil, fmt.Errorf("unsupported value type: %T", v)
}
}