encoding/jsonschema: fix decoding of $id

When decoding "$id", jsonschema decoder mistakenly assumed that
the schema is an object and added an object constraint with the id tag.

This change postpones the attachment of id tag until an object
constraint is added or the schema is finalizing.

Fixes #3361

Change-Id: I7829af165af726524d48022fc87ed538b7e451cd
Signed-off-by: haoqixu <[email protected]>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1199139
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

encoding/jsonschema/constraints.go

@@ -15,7 +15,6 @@
 package jsonschema
 
 import (
-	"fmt"
 	"math/big"
 	"path"
 	"regexp"
@@ -143,13 +142,7 @@ var constraints = []*constraint{
 			return
 		}
 		s.id = u
-
-		obj := s.object(n)
-
-		// TODO: handle the case where this is always defined and we don't want
-		// to include the default value.
-		obj.Elts = append(obj.Elts, &ast.Attribute{
-			Text: fmt.Sprintf("@jsonschema(id=%q)", u)})
+		s.idPos = n.Pos()
 	}),
 
 	// Generic constraint

encoding/jsonschema/decode.go

@@ -336,6 +336,7 @@ type state struct {
 	exclusiveMax bool // For OpenAPI and legacy support.
 	jsonschema   string
 	id           *url.URL // base URI for $ref
+	idPos        token.Pos
 
 	definitions []ast.Decl
 
@@ -362,9 +363,19 @@ type refs struct {
 	refs  []*ast.Ident
 }
 
+func (s *state) idTag() *ast.Attribute {
+	return &ast.Attribute{
+		At:   s.idPos,
+		Text: fmt.Sprintf("@jsonschema(id=%q)", s.id)}
+}
+
 func (s *state) object(n cue.Value) *ast.StructLit {
 	if s.obj == nil {
 		s.obj = &ast.StructLit{}
+
+		if s.id != nil {
+			s.obj.Elts = append(s.obj.Elts, s.idTag())
+		}
 		s.add(n, objectType, s.obj)
 	}
 	return s.obj
@@ -382,7 +393,8 @@ func (s *state) hasConstraints() bool {
 	return len(s.patterns) > 0 ||
 		s.title != "" ||
 		s.description != "" ||
-		s.obj != nil
+		s.obj != nil ||
+		s.id != nil
 }
 
 const allTypes = cue.NullKind | cue.BoolKind | cue.NumberKind | cue.IntKind |
@@ -499,6 +511,17 @@ outer:
 
 	s.linkReferences()
 
+	// If an "$id" exists and has not been included in any object constraints
+	if s.id != nil && s.obj == nil {
+		if st, ok := e.(*ast.StructLit); ok {
+			st.Elts = append([]ast.Decl{s.idTag()}, st.Elts...)
+		} else {
+			st = &ast.StructLit{Elts: []ast.Decl{s.idTag()}}
+			st.Elts = append(st.Elts, &ast.EmbedDecl{Expr: e})
+			e = st
+		}
+	}
+
 	return e
 }
 

encoding/jsonschema/testdata/id_in_oneOf.txtar

@@ -0,0 +1,28 @@
+-- schema.json --
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "https://test.example/foo",
+  "oneOf": [
+      {
+          "$schema": "http://json-schema.org/draft-07/schema#",
+          "$id": "https://1.test.example/string",
+          "type": "string"
+      },
+      {
+          "$schema": "http://json-schema.org/draft-07/schema#",
+          "$id": "https://2.test.example/object",
+          "type": "object"
+      }
+  ]
+}
+
+-- out/decode/cue --
+@jsonschema(schema="http://json-schema.org/draft-07/schema#")
+@jsonschema(id="https://test.example/foo")
+{
+	@jsonschema(id="https://1.test.example/string")
+	string
+} | {
+	@jsonschema(id="https://2.test.example/object")
+	...
+}

encoding/jsonschema/testdata/id_scalar.txtar

@@ -0,0 +1,12 @@
+-- schema.json --
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "http://cuelang.org/go/encoding/openapi/testdata/id_scalar.json",
+
+  "type": "string"
+}
+
+-- out/decode/cue --
+@jsonschema(schema="http://json-schema.org/draft-07/schema#")
+@jsonschema(id="http://cuelang.org/go/encoding/openapi/testdata/id_scalar.json")
+string