Allow arrays to use allowNull keyword (#26)

fixtures/arrays.json

@@ -0,0 +1,28 @@
+{
+  "$ref": "#/definitions/testmodels.Arrays",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "testmodels.Arrays": {
+      "additionalProperties": false,
+      "properties": {
+        "pets": {
+          "items": {
+            "type": "integer"
+          },
+          "oneOf": [
+            {
+              "type": "array"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        }
+      },
+      "required": [
+        "pets"
+      ],
+      "type": "object"
+    }
+  }
+}

internal/testmodels/arrays.go

@@ -0,0 +1,5 @@
+package testmodels
+
+type Arrays struct {
+	Pets []int `json:"pets" jsonschema:"allowNull"`
+}

reflect.go

@@ -525,6 +525,16 @@ func (t *Type) arrayKeywords(tags []string) {
 			case "uniqueItems":
 				t.UniqueItems = true
 			}
+		} else {
+			name := nameValue[0]
+			switch name {
+			case "allowNull":
+				t.OneOf = []*Type{
+					{Type: t.Type},
+					{Type: "null"},
+				}
+				t.Type = ""
+			}
 		}
 	}
 }

reflect_test.go

@@ -30,6 +30,7 @@ var schemaGenerationTests = []testSet{
 	{&jsonschema.Reflector{}, "fixtures/test_min_max_items.json", testmodels.SliceTestType{}},
 	{&jsonschema.Reflector{}, "fixtures/test_recursion.json", testmodels.TestFamilyMember{}},
 	{&jsonschema.Reflector{}, "fixtures/duplicate_embedded_fields.json", testmodels.Root{}},
+	{&jsonschema.Reflector{}, "fixtures/arrays.json", testmodels.Arrays{}},
 }
 
 func TestSchemaGeneration(t *testing.T) {

subschemas_switch.go

@@ -46,7 +46,6 @@ type SchemaSwitch struct {
 
 var schemaCaseType = reflect.TypeOf((*schemaCase)(nil)).Elem()
 
-
 // Appends jsonschema rules from Case interface to the jsonschema for the struct that implements them
 func (r *Reflector) addSubschemasForSwitch(st *Type, definitions Definitions, t reflect.Type) {
 	if st == nil {
@@ -65,8 +64,8 @@ func (r *Reflector) addSubschemasForSwitch(st *Type, definitions Definitions, t
 func (r *Reflector) reflectCases(definitions Definitions, sc SchemaSwitch) []*Type {
 	//Build order when not provided my the user of this library
 	if len(sc.Order) == 0 {
-		for key := range sc.Cases{
-			sc.Order = append(sc.Order,key)
+		for key := range sc.Cases {
+			sc.Order = append(sc.Order, key)
 		}
 	}
 	casesList := make([]*Type, 0)