feat(jsonschema): Field to tell if RootSchema is an array or object.

keywords.go

@@ -59,6 +59,14 @@ func NewType() Validator {
 	return &Type{}
 }
 
+// FirstValue returns the first element in the values of this type.
+func (t Type) FirstValue() string {
+	if len(t.vals) == 0 {
+		return ""
+	}
+	return t.vals[0]
+}
+
 // Validate checks to see if input data satisfies the type constraint
 func (t Type) Validate(propPath string, data interface{}, errs *[]ValError) {
 	jt := DataType(data)

schema.go

@@ -46,6 +46,15 @@ type RootSchema struct {
 	// for current and previous published drafts of JSON Schema
 	// vocabularies as deemed reasonable.
 	SchemaURI string `json:"$schema"`
+	// Whether the top-level of the schema is an array or not.
+	// Assume it's an object otherwise.
+	TopIsArray bool
+}
+
+func determineTopIsArray(sch *Schema) bool {
+	validator := sch.Validators["type"]
+	typeValidator, ok := validator.(*Type)
+	return ok && typeValidator.FirstValue() == "array"
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface for
@@ -55,6 +64,7 @@ func (rs *RootSchema) UnmarshalJSON(data []byte) error {
 	if err := json.Unmarshal(data, sch); err != nil {
 		return err
 	}
+	topIsArray := determineTopIsArray(sch)
 
 	if sch.schemaType == schemaTypeFalse || sch.schemaType == schemaTypeTrue {
 		*rs = RootSchema{Schema: *sch}
@@ -69,8 +79,9 @@ func (rs *RootSchema) UnmarshalJSON(data []byte) error {
 	}
 
 	root := &RootSchema{
-		Schema:    *sch,
-		SchemaURI: suri.SchemaURI,
+		Schema:     *sch,
+		SchemaURI:  suri.SchemaURI,
+		TopIsArray: topIsArray,
 	}
 
 	// collect IDs for internal referencing:
@@ -122,8 +133,9 @@ func (rs *RootSchema) UnmarshalJSON(data []byte) error {
 	}
 
 	*rs = RootSchema{
-		Schema:    *sch,
-		SchemaURI: suri.SchemaURI,
+		Schema:     *sch,
+		SchemaURI:  suri.SchemaURI,
+		TopIsArray: topIsArray,
 	}
 	return nil
 }

schema_test.go

@@ -79,6 +79,39 @@ func ExampleBasic() {
 	// /friends/0: {"firstName":"Nas"} "lastName" value is required
 }
 
+func TestTopLevelType(t *testing.T) {
+	schemaObject := []byte(`{
+    "title": "Car",
+    "type": "object",
+    "properties": {
+        "color": {
+            "type": "string"
+        }
+    },
+    "required": ["color"]
+}`)
+	rs := &RootSchema{}
+	if err := json.Unmarshal(schemaObject, rs); err != nil {
+		panic("unmarshal schema: " + err.Error())
+	}
+	if rs.TopIsArray {
+		t.Errorf("error: schemaObject should not be an array")
+	}
+
+	schemaArray := []byte(`{
+    "title": "Cities",
+    "type": "array",
+    "items" : { "title" : "REFERENCE", "$ref" : "#" }
+}`)
+	rs = &RootSchema{}
+	if err := json.Unmarshal(schemaArray, rs); err != nil {
+		panic("unmarshal schema: " + err.Error())
+	}
+	if !rs.TopIsArray {
+		t.Errorf("error: schemaArray should not be an object")
+	}
+}
+
 func TestMust(t *testing.T) {
 	defer func() {
 		if r := recover(); r != nil {