example: add bytecount vocab

Author: santhosh-tekuri

example_vocab_bytecount_test.go

@@ -0,0 +1,149 @@
+package jsonschema_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"strconv"
+	"strings"
+
+	"github.com/santhosh-tekuri/jsonschema/v6"
+	"golang.org/x/text/message"
+)
+
+// SchemaExt --
+
+type ByteCount struct {
+	maxBytes *int
+	minBytes *int
+}
+
+func (s *ByteCount) Validate(ctx *jsonschema.ValidatorContext, v any) {
+	str, ok := v.(string)
+	if !ok {
+		return
+	}
+	if s.maxBytes != nil && len(str) > *s.maxBytes {
+		ctx.AddError(&MaxBytes{Got: len(str), Want: *s.maxBytes})
+	}
+	if s.minBytes != nil && len(str) < *s.minBytes {
+		ctx.AddError(&MinBytes{Got: len(str), Want: *s.maxBytes})
+	}
+}
+
+// Vocab --
+
+func ByteCountVocab() *jsonschema.Vocabulary {
+	url := "http://example.com/meta/byte-count"
+	schema, err := jsonschema.UnmarshalJSON(strings.NewReader(`{
+		"properties": {
+			"maxBytes": { "type": "integer", "minimum": 0 },
+			"minBytes": { "type": "integer", "minimum": 0 }
+		}
+	}`))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	c := jsonschema.NewCompiler()
+	if err := c.AddResource(url, schema); err != nil {
+		log.Fatal(err)
+	}
+	sch, err := c.Compile(url)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	return &jsonschema.Vocabulary{
+		URL:     url,
+		Schema:  sch,
+		Compile: compileByteCount,
+	}
+}
+
+func numValue(obj map[string]any, prop string) *int {
+	v, ok := obj[prop]
+	if !ok {
+		return nil
+	}
+	switch v.(type) {
+	case json.Number, float32, float64, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
+		if n, err := strconv.Atoi(fmt.Sprint(v)); err == nil {
+			return &n
+		}
+	}
+	return nil
+}
+
+func compileByteCount(ctx *jsonschema.CompilerContext, obj map[string]any) (jsonschema.SchemaExt, error) {
+	max := numValue(obj, "maxBytes")
+	min := numValue(obj, "minBytes")
+	if max == nil && min == nil {
+		return nil, nil
+	}
+	return &ByteCount{maxBytes: max, minBytes: min}, nil
+}
+
+// ErrorKind --
+
+type MaxBytes struct {
+	Got, Want int
+}
+
+func (*MaxBytes) KeywordPath() []string {
+	return []string{"maxBytes"}
+}
+
+func (k *MaxBytes) LocalizedString(p *message.Printer) string {
+	return p.Sprintf("maxBytes: got %d, want %d", k.Got, k.Want)
+}
+
+type MinBytes struct {
+	Got, Want int
+}
+
+func (*MinBytes) KeywordPath() []string {
+	return []string{"minBytes"}
+}
+
+func (k *MinBytes) LocalizedString(p *message.Printer) string {
+	return p.Sprintf("minBytes: got %d, want %d", k.Got, k.Want)
+}
+
+// Example --
+
+func Example_vocab_bytecount() {
+	schema, err := jsonschema.UnmarshalJSON(strings.NewReader(`{
+		"properties": {
+			"name": {
+				"type": "string",
+				"maxBytes": 5
+			}
+		}
+	}`))
+	if err != nil {
+		log.Fatal(err)
+	}
+	inst, err := jsonschema.UnmarshalJSON(strings.NewReader(`
+		{ "name": "helloworld" }
+	`))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	c := jsonschema.NewCompiler()
+	c.AssertVocabs()
+	c.RegisterVocabulary(ByteCountVocab())
+	if err := c.AddResource("schema.json", schema); err != nil {
+		log.Fatal(err)
+	}
+	sch, err := c.Compile("schema.json")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = sch.Validate(inst)
+	fmt.Println("valid:", err == nil)
+	// Output:
+	// valid: false
+}