Documentation
¶
Index ¶
- Variables
- func Indent(dst *bytes.Buffer, src []byte, prefix string, indent string) error
- func IndentString(dst *bytes.Buffer, src string, prefix string, indent string) error
- func NewDecoder(r io.Reader) *json.Decoder
- func NewEncoder(w io.Writer) *json.Encoder
- func TUnmarshal[T any](data []byte) (T, error)
- func TUnmarshalString[T any](data string) (T, error)
- func Unmarshal(data []byte, str any) error
- func UnmarshalContext(ctx context.Context, data []byte, v any) error
- func UnmarshalString(data string, str any) error
- func UnmarshalStringContext(ctx context.Context, data string, v any) error
- type M
- type RawMessage
Constants ¶
This section is empty.
Variables ¶
var ErrNilPointer error = &err.Err{Op: "json.RawMessage", Err: "UnmarshalJSON on nil pointer"}
Functions ¶
func Indent ¶ added in v1.5.5
Indent appends to dst an indented form of the JSON-encoded src.
Each element in a JSON object or array begins on a new, indented line beginning with prefix followed by one or more copies of indent according to the indentation nesting.
The data appended to dst does not begin with the prefix nor any indentation, to make it easier to embed inside other formatted JSON data.
Although leading space characters (space, tab, carriage return, newline) at the beginning of src are dropped, trailing space characters at the end of src are preserved and copied to dst. For example, if src has no trailing spaces, neither will dst; if src ends in a trailing newline, so will dst.
func IndentString ¶ added in v1.5.5
Indent appends to dst an indented form of the JSON-encoded src.
Each element in a JSON object or array begins on a new, indented line beginning with prefix followed by one or more copies of indent according to the indentation nesting.
The data appended to dst does not begin with the prefix nor any indentation, to make it easier to embed inside other formatted JSON data.
Although leading space characters (space, tab, carriage return, newline) at the beginning of src are dropped, trailing space characters at the end of src are preserved and copied to dst. For example, if src has no trailing spaces, neither will dst; if src ends in a trailing newline, so will dst.
func NewDecoder ¶ added in v1.5.5
NewDecoder returns a new decoder that reads from r.
The decoder introduces its own buffering and may read data from r beyond the JSON values requested.
func NewEncoder ¶ added in v1.5.5
NewEncoder returns a new encoder that writes to w.
func TUnmarshal ¶ added in v1.24.0
Example:
func main(){
data := []byte(`{"type":"object","properties":{"a":{"type":"integer"}}}`)
str, err := json.TUnmarshal[Main](data)
fmt.Println(str.Type)
}
func TUnmarshalString ¶ added in v1.24.0
Example:
func main(){
data := `{"type":"object","properties":{"a":{"type":"integer"}}}`
str, err := json.TUnmarshalString[Main](data)
fmt.Println(str.Type)
}
func Unmarshal ¶
Unmarshal parses the JSON-encoded data and stores the result in the value pointed to by v. If v is nil or not a pointer, Unmarshal returns an InvalidUnmarshalError.
Unmarshal uses the inverse of the encodings that Marshal uses, allocating maps, slices, and pointers as necessary, with the following additional rules:
To unmarshal JSON into a pointer, Unmarshal first handles the case of the JSON being the JSON literal null. In that case, Unmarshal sets the pointer to nil. Otherwise, Unmarshal unmarshals the JSON into the value pointed at by the pointer. If the pointer is nil, Unmarshal allocates a new value for it to point to.
To unmarshal JSON into a value implementing the Unmarshaler interface, Unmarshal calls that value's UnmarshalJSON method, including when the input is a JSON null. Otherwise, if the value implements encoding.TextUnmarshaler and the input is a JSON quoted string, Unmarshal calls that value's UnmarshalText method with the unquoted form of the string.
To unmarshal JSON into a struct, Unmarshal matches incoming object keys to the keys used by Marshal (either the struct field name or its tag), preferring an exact match but also accepting a case-insensitive match. By default, object keys which don't have a corresponding struct field are ignored (see Decoder.DisallowUnknownFields for an alternative).
To unmarshal JSON into an interface value, Unmarshal stores one of these in the interface value:
bool, for JSON booleans
float64, for JSON numbers
string, for JSON strings
[]interface{}, for JSON arrays
map[string]interface{}, for JSON objects
nil for JSON null
To unmarshal a JSON array into a slice, Unmarshal resets the slice length to zero and then appends each element to the slice. As a special case, to unmarshal an empty JSON array into a slice, Unmarshal replaces the slice with a new empty slice.
To unmarshal a JSON array into a Go array, Unmarshal decodes JSON array elements into corresponding Go array elements. If the Go array is smaller than the JSON array, the additional JSON array elements are discarded. If the JSON array is smaller than the Go array, the additional Go array elements are set to zero values.
To unmarshal a JSON object into a map, Unmarshal first establishes a map to use. If the map is nil, Unmarshal allocates a new map. Otherwise Unmarshal reuses the existing map, keeping existing entries. Unmarshal then stores key-value pairs from the JSON object into the map. The map's key type must either be any string type, an integer, implement json.Unmarshaler, or implement encoding.TextUnmarshaler.
If a JSON value is not appropriate for a given target type, or if a JSON number overflows the target type, Unmarshal skips that field and completes the unmarshaling as best it can. If no more serious errors are encountered, Unmarshal returns an UnmarshalTypeError describing the earliest such error. In any case, it's not guaranteed that all the remaining fields following the problematic one will be unmarshaled into the target object.
The JSON null value unmarshals into an interface, map, pointer, or slice by setting that Go value to nil. Because null is often used in JSON to mean “not present,” unmarshaling a JSON null into any other Go type has no effect on the value and produces no error.
When unmarshaling quoted strings, invalid UTF-8 or invalid UTF-16 surrogate pairs are not treated as an error. Instead, they are replaced by the Unicode replacement character U+FFFD.
func UnmarshalContext ¶ added in v0.0.2
UnmarshalContext parses the JSON-encoded data and stores the result in the value pointed to by v. If you implement the UnmarshalerContext interface, call it with ctx as an argument.
func UnmarshalString ¶ added in v0.0.2
Unmarshal For String
func UnmarshalStringContext ¶ added in v0.0.2
UnmarshalContext parses the JSON-encoded data and stores the result in the value pointed to by v. If you implement the UnmarshalerContext interface, call it with ctx as an argument.
Use String Data.
Types ¶
type M ¶ added in v1.2.0
type M struct {
// contains filtered or unexported fields
}
func Marshal ¶
Marshal returns the JSON encoding of v.
Marshal traverses the value v recursively. If an encountered value implements the Marshaler interface and is not a nil pointer, Marshal calls its MarshalJSON method to produce JSON. If no MarshalJSON method is present but the value implements encoding.TextMarshaler instead, Marshal calls its MarshalText method and encodes the result as a JSON string. The nil pointer exception is not strictly necessary but mimics a similar, necessary exception in the behavior of UnmarshalJSON.
Otherwise, Marshal uses the following type-dependent default encodings:
Boolean values encode as JSON booleans.
Floating point, integer, and Number values encode as JSON numbers.
String values encode as JSON strings coerced to valid UTF-8, replacing invalid bytes with the Unicode replacement rune. The angle brackets "<" and ">" are escaped to "\u003c" and "\u003e" to keep some browsers from misinterpreting JSON output as HTML. Ampersand "&" is also escaped to "\u0026" for the same reason. This escaping can be disabled using an Encoder that had SetEscapeHTML(false) called on it.
Array and slice values encode as JSON arrays, except that []byte encodes as a base64-encoded string, and a nil slice encodes as the null JSON value.
Struct values encode as JSON objects. Each exported struct field becomes a member of the object, using the field name as the object key, unless the field is omitted for one of the reasons given below.
The encoding of each struct field can be customized by the format string stored under the "json" key in the struct field's tag. The format string gives the name of the field, possibly followed by a comma-separated list of options. The name may be empty in order to specify options without overriding the default field name.
The "omitempty" option specifies that the field should be omitted from the encoding if the field has an empty value, defined as false, 0, a nil pointer, a nil interface value, and any empty array, slice, map, or string.
As a special case, if the field tag is "-", the field is always omitted. Note that a field with name "-" can still be generated using the tag "-,".
Examples of struct field tags and their meanings:
// Field appears in JSON as key "myName". Field int `json:"myName"` // Field appears in JSON as key "myName" and // the field is omitted from the object if its value is empty, // as defined above. Field int `json:"myName,omitempty"` // Field appears in JSON as key "Field" (the default), but // the field is skipped if empty. // Note the leading comma. Field int `json:",omitempty"` // Field is ignored by this package. Field int `json:"-"` // Field appears in JSON as key "-". Field int `json:"-,"`
The "string" option signals that a field is stored as JSON inside a JSON-encoded string. It applies only to fields of string, floating point, integer, or boolean types. This extra level of encoding is sometimes used when communicating with JavaScript programs:
Int64String int64 `json:",string"`
The key name will be used if it's a non-empty string consisting of only Unicode letters, digits, and ASCII punctuation except quotation marks, backslash, and comma.
Anonymous struct fields are usually marshaled as if their inner exported fields were fields in the outer struct, subject to the usual Go visibility rules amended as described in the next paragraph. An anonymous struct field with a name given in its JSON tag is treated as having that name, rather than being anonymous. An anonymous struct field of interface type is treated the same as having that type as its name, rather than being anonymous.
The Go visibility rules for struct fields are amended for JSON when deciding which field to marshal or unmarshal. If there are multiple fields at the same level, and that level is the least nested (and would therefore be the nesting level selected by the usual Go rules), the following extra rules apply:
1) Of those fields, if any are JSON-tagged, only tagged fields are considered, even if there are multiple untagged fields that would otherwise conflict.
2) If there is exactly one field (tagged or not according to the first rule), that is selected.
3) Otherwise there are multiple fields, and all are ignored; no error occurs.
Handling of anonymous struct fields is new in Go 1.1. Prior to Go 1.1, anonymous struct fields were ignored. To force ignoring of an anonymous struct field in both current and earlier versions, give the field a JSON tag of "-".
Map values encode as JSON objects. The map's key type must either be a string, an integer type, or implement encoding.TextMarshaler. The map keys are sorted and used as JSON object keys by applying the following rules, subject to the UTF-8 coercion described for string values above:
- string keys are used directly
- encoding.TextMarshalers are marshaled
- integer keys are converted to strings
Pointer values encode as the value pointed to. A nil pointer encodes as the null JSON value.
Interface values encode as the value contained in the interface. A nil interface value encodes as the null JSON value.
Channel, complex, and function values cannot be encoded in JSON. Attempting to encode such a value causes Marshal to return an UnsupportedTypeError.
JSON cannot represent cyclic data structures and Marshal does not handle them. Passing cyclic structures to Marshal will result in an infinite recursion.
func MarshalContext ¶ added in v1.5.5
MarshalContext returns the JSON encoding of v with context.Context and EncodeOption.
func MarshalIndent ¶ added in v1.5.3
MarshalIndent is like Marshal but applies Indent to format the output. Each JSON element in the output will begin on a new line beginning with prefix followed by one or more copies of indent according to the indentation nesting.
func MarshalNoEscape ¶ added in v1.5.5
MarshalNoEscape returns the JSON encoding of v and doesn't escape v.
type RawMessage ¶ added in v1.5.6
type RawMessage []byte
RawMessage is a raw encoded JSON value. It implements Marshaler and Unmarshaler and can be used to delay JSON decoding or precompute a JSON encoding.
func (RawMessage) MarshalJSON ¶ added in v1.5.6
func (m RawMessage) MarshalJSON() ([]byte, error)
MarshalJSON returns m as the JSON encoding of m.
func (*RawMessage) UnmarshalJSON ¶ added in v1.5.6
func (m *RawMessage) UnmarshalJSON(data []byte) error
UnmarshalJSON sets *m to a copy of data.
Source Files