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field.go
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field.go
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package dal
import (
"encoding/json"
"fmt"
"reflect"
"strings"
"time"
"github.com/fatih/structs"
"github.com/ghetzel/go-stockutil/sliceutil"
"github.com/ghetzel/go-stockutil/typeutil"
)
var DefaultFieldCodec = `json`
var IntIsProbablyUnixEpochSeconds int64 = 4294967296
type Field struct {
// The name of the field
Name string `json:"name"`
// A description of the field used in help text
Description string `json:"description,omitempty"`
// The data type of the field
Type Type `json:"type"`
// For complex field types (tuples, objects); the data type of the key portion
KeyType Type `json:"keytype,omitempty"`
// For complex field types (arrays, sets, lists); the data type of the contained values
Subtype Type `json:"subtype,omitempty"`
// The length constraint for values in the field (where supported)
Length int `json:"length,omitempty"`
// The precision of stored values in the field (where supported)
Precision int `json:"precision,omitempty"`
// Whether the field is an identity field (don't use this, configure the identity on the
// Collection instead)
Identity bool `json:"identity,omitempty"`
// Whether the field is a key field in a composite key Collection
Key bool `json:"key,omitempty"`
// Whether the field can store a null/empty value
Required bool `json:"required,omitempty"`
// Enforces that the field value must be unique across the entire Collection (where supported)
Unique bool `json:"unique,omitempty"`
// The name of a group of unique fields that, taken together, must be unique across the entire
// Collection (where supported)
UniqueGroup string `json:"unique_group,omitempty"`
// The default value of the field is one is not explicitly specified. Can be any type or a
// function that takes zero arguments and returns a single value.
DefaultValue interface{} `json:"default,omitempty"`
// Represents the native datatype of the underlying Backend object (read only)
NativeType string `json:"native_type,omitempty"`
// Specify that the field should not be modified. This is not enforced in Pivot, but rather
// serves as a note to applications implementing interactions with the Pivot API.
NotUserEditable bool `json:"not_user_editable"`
// Whether this field's validator(s) should be used to validate data being retrieved from the
// backend. Invalid data (possibly created outside of Pivot) will cause Retrieve() calls to
// return a validation error.
ValidateOnPopulate bool `json:"validate_on_populate,omitempty"`
// A function that is used to validate the field's value before performing any create, update,
// and (optionally) retrieval operations.
Validator FieldValidatorFunc `json:"-"`
// A function that can modify values before any create or update operations. Formatters run
// before Validators, giving users the opportunity to ensure a valid value is in the data
// structure before validation runs.
Formatter FieldFormatterFunc `json:"-"`
// A declarative form of the Validator configuration that uses pre-defined validators. Primarily
// used when storing schema declarations in external JSON files.
ValidatorConfig map[string]interface{} `json:"validators,omitempty"`
// A declarative form of the Formatter configuration that uses pre-defined validators. Primarily
// used when storing schema declarations in external JSON files.
FormatterConfig map[string]interface{} `json:"formatters,omitempty"`
// Used to store the order this field appears in the source database.
Index int `json:"index,omitempty"`
// Specify a relationship between this field and another collection.
//
// If given a string, it will be interpreted as a collection name and a
// constaint against that collection's identity field will be created.
//
// If given a *Collection, the same behavior as above will occur, but using
// the Collection.Name from the given struct.
//
// If given a Constraint, the constraint will be added to this field's
// parent collection with the "On" field set to this field's name.
BelongsTo interface{} `json:"belongs_to,omitempty"`
// Specifies that the field may not be updated, only read. Attempts to update the field will be silently discarded.
ReadOnly bool `json:"readonly,omitempty"`
}
func (self *Field) normalizeType(in interface{}) (interface{}, error) {
variant := typeutil.V(in)
switch self.Type {
case StringType:
if !self.Required && variant.IsZero() {
in = nil
} else {
in = variant.String()
}
case BooleanType:
in = variant.Bool()
case IntType:
in = variant.Int()
case FloatType:
in = variant.Float()
case ArrayType:
if in == nil {
return nil, nil
} else if typeutil.IsArray(in) {
if arr := sliceutil.Sliceify(in); len(arr) > 0 {
return arr, nil
} else {
return make([]interface{}, 0), nil
}
} else {
var raw []byte
var arr []interface{}
if typeutil.IsKindOfString(in) {
raw = []byte(typeutil.String(in))
} else if r, ok := in.([]byte); ok {
raw = r
} else if r, ok := in.([]uint8); ok {
raw = []byte(r)
} else {
return nil, fmt.Errorf("Cannot use %T as an ArrayType input", in)
}
if err := json.Unmarshal(raw, &arr); err == nil {
return arr, nil
} else {
return nil, err
}
}
case ObjectType:
if in != nil {
if native, ok := in.(map[string]interface{}); ok {
return native, nil
} else if typeutil.IsMap(in) {
return variant.MapNative(), nil
} else {
var raw []byte
var obj map[string]interface{}
if typeutil.IsStruct(in) {
if r, err := json.Marshal(in); err == nil {
raw = r
} else {
return nil, fmt.Errorf("Cannot convert %T to map: %v", in, err)
}
} else if typeutil.IsKindOfString(in) {
raw = []byte(typeutil.String(in))
} else if r, ok := in.([]byte); ok {
raw = r
} else if r, ok := in.([]uint8); ok {
raw = []byte(r)
} else {
return nil, fmt.Errorf("Cannot use %T as an ObjectType input", in)
}
if err := json.Unmarshal(raw, &obj); err == nil {
return obj, nil
} else {
return nil, err
}
}
}
case TimeType:
if in == nil {
in = time.Time{}
} else if inInt64, ok := in.(int64); ok {
// parse incoming int64s as epoch or epoch milliseconds
if inInt64 < IntIsProbablyUnixEpochSeconds {
in = time.Unix(inInt64, 0)
} else {
in = time.Unix(0, inInt64)
}
} else {
in = variant.Time()
}
default:
switch strings.ToLower(fmt.Sprintf("%v", in)) {
case `null`, `nil`:
in = nil
}
}
return in, nil
}
func (self *Field) ConvertValue(in interface{}) (interface{}, error) {
if norm, err := self.normalizeType(in); err == nil {
in = norm
} else {
return nil, err
}
// decide what to do with the now-normalized type
if typeutil.IsZero(in) {
if self.DefaultValue != nil {
return self.GetDefaultValue(), nil
} else if self.Type == BooleanType && in != nil {
return false, nil
} else if self.Required {
return self.GetTypeInstance(), nil
}
}
return in, nil
}
func (self *Field) GetDefaultValue() interface{} {
if self.DefaultValue == nil {
return nil
} else if typeutil.IsFunctionArity(self.DefaultValue, 0, 1) {
if values := reflect.ValueOf(self.DefaultValue).Call(make([]reflect.Value, 0)); len(values) == 1 {
if norm, err := self.normalizeType(values[0].Interface()); err == nil {
return norm
}
}
}
if norm, err := self.normalizeType(self.DefaultValue); err == nil {
return norm
} else {
return nil
}
}
func (self *Field) GetTypeInstance() interface{} {
switch self.Type {
case StringType:
return ``
case BooleanType:
return false
case IntType:
return int64(0)
case FloatType:
return float64(0.0)
case TimeType:
return time.Time{}
case ObjectType:
return make(map[string]interface{})
case ArrayType:
return make([]interface{}, 0)
default:
return make([]byte, 0)
}
}
func (self *Field) Validate(value interface{}) error {
// automatically validate that required fields aren't being given a nil value
if self.Required && value == nil {
return fmt.Errorf("field %q is required", self.Name)
}
if self.Validator == nil {
return nil
} else if err := self.Validator(value); err != nil {
return fmt.Errorf("validation error: %v", err)
} else {
return nil
}
}
func (self *Field) Format(value interface{}, op FieldOperation) (interface{}, error) {
if self.Formatter == nil {
return value, nil
} else {
if v, err := self.Formatter(value, op); err == nil {
return v, nil
} else {
return v, fmt.Errorf("formatter error: %v", err)
}
}
}
func (self *Field) Diff(other *Field) []*SchemaDelta {
diff := make([]*SchemaDelta, 0)
mine := structs.New(self)
theirs := structs.New(other)
for _, myField := range mine.Fields() {
if myField.IsExported() {
theirField, _ := theirs.FieldOk(myField.Name())
deltaIssue := UnknownIssue
switch myField.Name() {
// skip parameters:
//
// NativeType:
// this is generally expected to be an output value from the database and not specified in schema definitions
// Description:
// this is largely for the use of the client application and won't always have a backend-persistent counterpart
// DefaultValue:
// this is a value that is interpreted by the backend and may not be retrievable after definition
//
case `NativeType`, `Description`, `DefaultValue`, `Validator`, `Formatter`, `FormatterConfig`, `ValidatorConfig`, `Key`:
continue
case `Length`:
if myV := typeutil.Int(myField.Value()); myV > 0 {
if theirV := typeutil.Int(theirField.Value()); theirV > 0 {
// It is okay for lengths to exceed, but not be less than, our desired length
if theirV < myV {
diff = append(diff, &SchemaDelta{
Type: FieldDelta,
Issue: FieldLengthIssue,
Message: `length is shorter than desired`,
Name: self.Name,
Parameter: `Length`,
Desired: myV,
Actual: theirV,
})
}
}
}
continue
case `Type`:
if myT, ok := myField.Value().(Type); ok {
if theirT, ok := theirField.Value().(Type); ok {
if myT != theirT {
// ObjectType fields can be stored as a RawType on backends without
// a native object type, so we treat raw fields as object fields
if myT == ObjectType && theirT == RawType {
continue
}
// some backends store times as integers, so allow that too
if myT == TimeType && theirT == IntType {
continue
}
}
}
}
deltaIssue = FieldTypeIssue
fallthrough
default:
myV := myField.Value()
theirV := theirField.Value()
if deltaIssue == UnknownIssue {
deltaIssue = FieldPropertyIssue
}
if myV != theirV {
diff = append(diff, &SchemaDelta{
Type: FieldDelta,
Issue: deltaIssue,
Message: `values do not match`,
Name: self.Name,
Parameter: theirField.Name(),
Desired: myV,
Actual: theirV,
})
}
}
}
}
if len(diff) == 0 {
return nil
}
return diff
}
func (self *Field) MarshalJSON() ([]byte, error) {
type Alias Field
// this is a small pile or horrors that prevents infinite MarshalJSON stack
// overflow recursion sadness
if data, err := json.Marshal(&struct {
*Alias
}{
Alias: (*Alias)(self),
}); err == nil {
return data, nil
} else {
return json.Marshal(&struct {
DefaultValue interface{} `json:"default,omitempty"`
*Alias
}{
DefaultValue: nil,
Alias: (*Alias)(self),
})
}
}
func (self *Field) UnmarshalJSON(b []byte) error {
type Alias Field
// this is a small pile or horrors that prevents infinite UnmarshalJSON stack
// overflow recursion sadness
if err := json.Unmarshal(b, &struct {
*Alias
}{
Alias: (*Alias)(self),
}); err == nil {
if len(self.FormatterConfig) > 0 {
if formatter, err := FormatterFromMap(self.FormatterConfig); err == nil {
self.Formatter = formatter
} else {
return fmt.Errorf("formatter error: %v", err)
}
}
if len(self.ValidatorConfig) > 0 {
if validator, err := ValidatorFromMap(self.ValidatorConfig); err == nil {
self.Validator = validator
} else {
return fmt.Errorf("validator error: %v", err)
}
}
return nil
} else {
return err
}
}
// Parses the value of BelongsTo into a valid Constraint
func (self *Field) BelongsToConstraint() *Constraint {
if self.BelongsTo != nil {
proposed := Constraint{
On: self.Name,
}
if cname, ok := self.BelongsTo.(string); ok { // given as string
proposed.Collection = cname
proposed.Field = DefaultIdentityField
} else if col, ok := self.BelongsTo.(*Collection); ok { // given as *Collection
proposed.Collection = col.Name
proposed.Field = col.KeyFieldNames()
} else if con, ok := self.BelongsTo.(Constraint); ok { // given as Constraint
proposed = con
proposed.On = self.Name
} else if con, ok := self.BelongsTo.(*Constraint); ok { // given as *Constraint
proposed = *con
proposed.On = self.Name
}
return &proposed
} else {
return nil
}
}