huma/schema.go
2020-03-29 21:28:33 -07:00

406 lines
12 KiB
Go

package huma
import (
"encoding/json"
"errors"
"fmt"
"net"
"net/url"
"reflect"
"regexp"
"strconv"
"strings"
"time"
)
// ErrSchemaInvalid is sent when there is a problem building the schema.
var ErrSchemaInvalid = errors.New("schema is invalid")
// SchemaMode defines whether the schema is being generated for read or
// write mode. Read-only fields are dropped when in write mode, for example.
type SchemaMode int
const (
// SchemaModeAll is for general purpose use and includes all fields.
SchemaModeAll SchemaMode = iota
// SchemaModeRead is for HTTP HEAD & GET and will hide write-only fields.
SchemaModeRead
// SchemaModeWrite is for HTTP POST, PUT, PATCH, DELETE and will hide
// read-only fields.
SchemaModeWrite
)
var (
timeType = reflect.TypeOf(time.Time{})
ipType = reflect.TypeOf(net.IP{})
uriType = reflect.TypeOf(url.URL{})
byteSliceType = reflect.TypeOf([]byte(nil))
)
// I returns a pointer to the given int. Useful helper function for pointer
// schema validators like MaxLength or MinItems.
func I(value uint64) *uint64 {
return &value
}
// F returns a pointer to the given float64. Useful helper function for pointer
// schema validators like Maximum or Minimum.
func F(value float64) *float64 {
return &value
}
// getTagValue returns a value of the schema's type for the given tag string.
// Uses JSON parsing if the schema is not a string.
func getTagValue(s *Schema, t reflect.Type, value string) (interface{}, error) {
if s.Type == "string" {
return value, nil
}
var v interface{}
if err := json.Unmarshal([]byte(value), &v); err != nil {
return nil, err
}
tv := reflect.TypeOf(v)
if v != nil && tv != t {
if !tv.ConvertibleTo(t) {
return nil, fmt.Errorf("unable to convert %v to %v: %w", tv, t, ErrSchemaInvalid)
}
v = reflect.ValueOf(v).Convert(t).Interface()
}
return v, nil
}
// Schema represents a JSON Schema which can be generated from Go structs
type Schema struct {
Type string `json:"type,omitempty"`
Description string `json:"description,omitempty"`
Items *Schema `json:"items,omitempty"`
Properties map[string]*Schema `json:"properties,omitempty"`
AdditionalProperties interface{} `json:"additionalProperties,omitempty"`
PatternProperties map[string]*Schema `json:"patternProperties,omitempty"`
Required []string `json:"required,omitempty"`
Format string `json:"format,omitempty"`
Enum []interface{} `json:"enum,omitempty"`
Default interface{} `json:"default,omitempty"`
Example interface{} `json:"example,omitempty"`
Minimum *float64 `json:"minimum,omitempty"`
ExclusiveMinimum *float64 `json:"exclusiveMinimum,omitempty"`
Maximum *float64 `json:"maximum,omitempty"`
ExclusiveMaximum *float64 `json:"exclusiveMaximum,omitempty"`
MultipleOf float64 `json:"multipleOf,omitempty"`
MinLength *uint64 `json:"minLength,omitempty"`
MaxLength *uint64 `json:"maxLength,omitempty"`
Pattern string `json:"pattern,omitempty"`
MinItems *uint64 `json:"minItems,omitempty"`
MaxItems *uint64 `json:"maxItems,omitempty"`
UniqueItems bool `json:"uniqueItems,omitempty"`
MinProperties *uint64 `json:"minProperties,omitempty"`
MaxProperties *uint64 `json:"maxProperties,omitempty"`
AllOf []*Schema `json:"allOf,omitempty"`
AnyOf []*Schema `json:"anyOf,omitempty"`
OneOf []*Schema `json:"oneOf,omitempty"`
Not *Schema `json:"not,omitempty"`
Nullable bool `json:"nullable,omitempty"`
ReadOnly bool `json:"readOnly,omitempty"`
WriteOnly bool `json:"writeOnly,omitempty"`
Deprecated bool `json:"deprecated,omitempty"`
}
// HasValidation returns true if at least one validator is set on the schema.
// This excludes the schema's type but includes most other fields and can be
// used to trigger additional slow validation steps when needed.
func (s *Schema) HasValidation() bool {
if s.Items != nil || len(s.Properties) > 0 || s.AdditionalProperties != nil || len(s.PatternProperties) > 0 || len(s.Required) > 0 || len(s.Enum) > 0 || s.Minimum != nil || s.ExclusiveMinimum != nil || s.Maximum != nil || s.ExclusiveMaximum != nil || s.MultipleOf != 0 || s.MinLength != nil || s.MaxLength != nil || s.Pattern != "" || s.MinItems != nil || s.MaxItems != nil || s.UniqueItems || s.MinProperties != nil || s.MaxProperties != nil || len(s.AllOf) > 0 || len(s.AnyOf) > 0 || len(s.OneOf) > 0 || s.Not != nil {
return true
}
return false
}
// GenerateSchema creates a JSON schema for a Go type. Struct field tags
// can be used to provide additional metadata such as descriptions and
// validation.
func GenerateSchema(t reflect.Type) (*Schema, error) {
return GenerateSchemaWithMode(t, SchemaModeAll, nil)
}
// GenerateSchemaWithMode creates a JSON schema for a Go type. Struct field
// tags can be used to provide additional metadata such as descriptions and
// validation. The mode can be all, read, or write. In read or write mode
// any field that is marked as the opposite will be excluded, e.g. a
// write-only field would not be included in read mode. If a schema is given
// as input, add to it, otherwise creates a new schema.
func GenerateSchemaWithMode(t reflect.Type, mode SchemaMode, schema *Schema) (*Schema, error) {
if schema == nil {
schema = &Schema{}
}
if t == ipType {
// Special case: IP address.
return &Schema{Type: "string", Format: "ipv4"}, nil
}
switch t.Kind() {
case reflect.Struct:
// Handle special cases.
switch t {
case timeType:
return &Schema{Type: "string", Format: "date-time"}, nil
case uriType:
return &Schema{Type: "string", Format: "uri"}, nil
}
properties := make(map[string]*Schema)
required := make([]string, 0)
schema.Type = "object"
schema.AdditionalProperties = false
for i := 0; i < t.NumField(); i++ {
f := t.Field(i)
jsonTags := strings.Split(f.Tag.Get("json"), ",")
name := strings.ToLower(f.Name)
if len(jsonTags) > 0 && jsonTags[0] != "" {
name = jsonTags[0]
}
s, err := GenerateSchemaWithMode(f.Type, mode, nil)
if err != nil {
return nil, err
}
properties[name] = s
if tag, ok := f.Tag.Lookup("description"); ok {
s.Description = tag
}
if tag, ok := f.Tag.Lookup("format"); ok {
s.Format = tag
}
if tag, ok := f.Tag.Lookup("enum"); ok {
s.Enum = []interface{}{}
for _, v := range strings.Split(tag, ",") {
parsed, err := getTagValue(s, f.Type, v)
if err != nil {
return nil, err
}
s.Enum = append(s.Enum, parsed)
}
}
if tag, ok := f.Tag.Lookup("default"); ok {
v, err := getTagValue(s, f.Type, tag)
if err != nil {
return nil, err
}
s.Default = v
}
if tag, ok := f.Tag.Lookup("example"); ok {
v, err := getTagValue(s, f.Type, tag)
if err != nil {
return nil, err
}
s.Example = v
}
if tag, ok := f.Tag.Lookup("minimum"); ok {
min, err := strconv.ParseFloat(tag, 64)
if err != nil {
return nil, err
}
s.Minimum = &min
}
if tag, ok := f.Tag.Lookup("exclusiveMinimum"); ok {
min, err := strconv.ParseFloat(tag, 64)
if err != nil {
return nil, err
}
s.ExclusiveMinimum = &min
}
if tag, ok := f.Tag.Lookup("maximum"); ok {
max, err := strconv.ParseFloat(tag, 64)
if err != nil {
return nil, err
}
s.Maximum = &max
}
if tag, ok := f.Tag.Lookup("exclusiveMaximum"); ok {
max, err := strconv.ParseFloat(tag, 64)
if err != nil {
return nil, err
}
s.ExclusiveMaximum = &max
}
if tag, ok := f.Tag.Lookup("multipleOf"); ok {
mof, err := strconv.ParseFloat(tag, 64)
if err != nil {
return nil, err
}
s.MultipleOf = mof
}
if tag, ok := f.Tag.Lookup("minLength"); ok {
min, err := strconv.ParseUint(tag, 10, 64)
if err != nil {
return nil, err
}
s.MinLength = &min
}
if tag, ok := f.Tag.Lookup("maxLength"); ok {
max, err := strconv.ParseUint(tag, 10, 64)
if err != nil {
return nil, err
}
s.MaxLength = &max
}
if tag, ok := f.Tag.Lookup("pattern"); ok {
s.Pattern = tag
if _, err := regexp.Compile(s.Pattern); err != nil {
return nil, err
}
}
if tag, ok := f.Tag.Lookup("minItems"); ok {
min, err := strconv.ParseUint(tag, 10, 64)
if err != nil {
return nil, err
}
s.MinItems = &min
}
if tag, ok := f.Tag.Lookup("maxItems"); ok {
max, err := strconv.ParseUint(tag, 10, 64)
if err != nil {
return nil, err
}
s.MaxItems = &max
}
if tag, ok := f.Tag.Lookup("uniqueItems"); ok {
if !(tag == "true" || tag == "false") {
return nil, fmt.Errorf("%s uniqueItems: boolean should be true or false: %w", f.Name, ErrSchemaInvalid)
}
s.UniqueItems = tag == "true"
}
if tag, ok := f.Tag.Lookup("minProperties"); ok {
min, err := strconv.ParseUint(tag, 10, 64)
if err != nil {
return nil, err
}
s.MinProperties = &min
}
if tag, ok := f.Tag.Lookup("maxProperties"); ok {
max, err := strconv.ParseUint(tag, 10, 64)
if err != nil {
return nil, err
}
s.MaxProperties = &max
}
if tag, ok := f.Tag.Lookup("nullable"); ok {
if !(tag == "true" || tag == "false") {
return nil, fmt.Errorf("%s nullable: boolean should be true or false: %w", f.Name, ErrSchemaInvalid)
}
s.Nullable = tag == "true"
}
if tag, ok := f.Tag.Lookup("readOnly"); ok {
if !(tag == "true" || tag == "false") {
return nil, fmt.Errorf("%s readOnly: boolean should be true or false: %w", f.Name, ErrSchemaInvalid)
}
s.ReadOnly = tag == "true"
if s.ReadOnly && mode == SchemaModeWrite {
delete(properties, name)
continue
}
}
if tag, ok := f.Tag.Lookup("writeOnly"); ok {
if !(tag == "true" || tag == "false") {
return nil, fmt.Errorf("%s writeOnly: boolean should be true or false: %w", f.Name, ErrSchemaInvalid)
}
s.WriteOnly = tag == "true"
if s.WriteOnly && mode == SchemaModeRead {
delete(properties, name)
continue
}
}
if tag, ok := f.Tag.Lookup("deprecated"); ok {
if !(tag == "true" || tag == "false") {
return nil, fmt.Errorf("%s deprecated: boolean should be true or false: %w", f.Name, ErrSchemaInvalid)
}
s.Deprecated = tag == "true"
}
optional := false
for _, tag := range jsonTags[1:] {
if tag == "omitempty" {
optional = true
}
}
if !optional {
required = append(required, name)
}
}
if len(properties) > 0 {
schema.Properties = properties
}
if len(required) > 0 {
schema.Required = required
}
case reflect.Map:
schema.Type = "object"
s, err := GenerateSchemaWithMode(t.Elem(), mode, nil)
if err != nil {
return nil, err
}
schema.AdditionalProperties = s
case reflect.Slice, reflect.Array:
schema.Type = "array"
s, err := GenerateSchemaWithMode(t.Elem(), mode, nil)
if err != nil {
return nil, err
}
schema.Items = s
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
schema.Type = "integer"
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
// Unsigned integers can't be negative.
schema.Type = "integer"
schema.Minimum = F(0.0)
case reflect.Float32, reflect.Float64:
schema.Type = "number"
case reflect.Bool:
schema.Type = "boolean"
case reflect.String:
schema.Type = "string"
case reflect.Ptr:
return GenerateSchemaWithMode(t.Elem(), mode, schema)
default:
return nil, fmt.Errorf("unsupported type %s from %s", t.Kind(), t)
}
return schema, nil
}