README
¶
jq
Go JSON structure query path getter/setter
package main
import (
"encoding/json"
"fmt"
"github.com/linkdata/jq"
)
const rawJson = `{
"name": "John Doe",
"age": 30,
"isStudent": false,
"hobbies": ["reading", "hiking", "gaming"],
"address": {
"street": "123 Main St",
"city": "Anytown",
"zip": "12345"
}
}`
type Address struct {
Street string `json:"street"`
City string `json:"city"`
Zip string `json:"zip"`
}
type Person struct {
Name string `json:"name"`
Age int `json:"age"`
IsStudent bool `json:"isStudent"`
Hobbies []string `json:"hobbies"`
Address Address `json:"address"`
}
func main() {
var person Person
var err error
if err = json.Unmarshal([]byte(rawJson), &person); err == nil {
var firsthobby string
if firsthobby, err = jq.GetAs[string](&person, "hobbies.0"); err == nil {
fmt.Println(firsthobby)
var address Address
if address, err = jq.GetAs[Address](&person, "address"); err == nil {
fmt.Println(address.City)
}
}
}
if err != nil {
panic(err)
}
// Output:
// reading
// Anytown
}
Checked updates
SetChecked tentatively applies the same operation as Set, then calls a
checker against the resulting object. A checker error restores the original
object and is returned unchanged. A checker panic also restores the object
before the panic continues.
The checker runs only when Set reports a write. It may inspect or marshal the
tentative object, but it must not mutate it. Callers are responsible for
synchronizing access throughout SetChecked, including while the checker runs.
Documentation
¶
Overview ¶
Example ¶
package main
import (
"encoding/json"
"fmt"
"github.com/linkdata/jq"
)
const rawJson = `{
"name": "John Doe",
"age": 30,
"isStudent": false,
"hobbies": ["reading", "hiking", "gaming"],
"address": {
"street": "123 Main St",
"city": "Anytown",
"zip": "12345"
}
}`
type Address struct {
Street string `json:"street"`
City string `json:"city"`
Zip string `json:"zip"`
}
type Person struct {
Name string `json:"name"`
Age int `json:"age"`
IsStudent bool `json:"isStudent"`
Hobbies []string `json:"hobbies"`
Address Address `json:"address"`
}
func main() {
var person Person
var err error
if err = json.Unmarshal([]byte(rawJson), &person); err == nil {
var firsthobby string
if firsthobby, err = jq.GetAs[string](&person, "hobbies.0"); err == nil {
fmt.Println(firsthobby)
var address Address
if address, err = jq.GetAs[Address](&person, "address"); err == nil {
fmt.Println(address.City)
}
}
}
if err != nil {
panic(err)
}
}
Output: reading Anytown
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ErrInvalidReceiver = errors.New("jq: invalid receiver")
ErrInvalidReceiver indicates a nil or non-pointer receiver.
Set and SetChecked require their first argument to be a non-nil pointer.
var ErrPathNotFound errPathNotFound
ErrPathNotFound is returned when a JSON path can't be resolved
var ErrTypeMismatch errTypeMismatch
ErrTypeMismatch is returned when a value does not have the expected type.
Functions ¶
func Get ¶
Get returns the value at jspath in obj.
An empty path returns obj itself unless obj is nil. Values containing maps, slices, or pointers may share their backing data with obj.
func GetAs ¶
GetAs returns the value at jspath in obj as T.
It returns ErrTypeMismatch when the resolved value is not assignable to T.
func Set ¶
Set updates jspath in obj and reports whether it performed a write.
obj must be a non-nil pointer. An empty path replaces the pointed-to value. A path into a settable slice may append one element by using an index equal to the slice's current length. Map paths address existing string-keyed entries and do not create new entries. A nil val stores the destination type's zero value.
Set leaves obj unchanged when it returns an error. It does not synchronize access to obj; callers must prevent concurrent reads and writes.
func SetChecked ¶ added in v0.2.0
SetChecked updates jspath only when check accepts the resulting object.
SetChecked first applies the same operation as Set. If Set reports a write, SetChecked calls check exactly once while obj contains the tentative result. A nil error commits the change. If check returns an error, SetChecked restores obj, returns false, and returns that error unchanged. If check panics, SetChecked restores obj before the panic continues. A nil check behaves like Set.
check is not called for an invalid operation or when Set reports no write. It may inspect obj, including by calling Get, but must not mutate obj or values reachable from it, call Set or SetChecked on them, or retain references into a rejected tentative value. Rollback covers only mutations made by SetChecked itself.
SetChecked does not synchronize access to obj. Callers must prevent concurrent access for the entire call, including while check runs.
Example ¶
package main
import (
"encoding/json"
"errors"
"fmt"
"github.com/linkdata/jq"
)
func main() {
value := []string{"one"}
maxBytes := len(`["one"]`)
_, err := jq.SetChecked(&value, "1", "two", func() (err error) {
var data []byte
if data, err = json.Marshal(value); err == nil && len(data) > maxBytes {
err = errors.New("value is too large")
}
return
})
fmt.Println(value)
fmt.Println(err)
}
Output: [one] value is too large
Types ¶
This section is empty.
Source Files