README

gojq

CI Status Go Report Card MIT License release pkg.go.dev

Pure Go implementation of jq

This is an implementation of jq command written in Go language. You can also embed gojq as a library to your Go products.

Usage

 $ echo '{"foo": 128}' | gojq '.foo'
128
 $ echo '{"a": {"b": 42}}' | gojq '.a.b'
42
 $ echo '{"id": "sample", "10": {"b": 42}}' | gojq '{(.id): .["10"].b}'
{
  "sample": 42
}
 $ echo '[{"id":1},{"id":2},{"id":3}]' | gojq '.[] | .id'
1
2
3
 $ echo '{"a":1,"b":2}' | gojq '.a += 1 | .b *= 2'
{
  "a": 2,
  "b": 4
}
 $ echo '{"a":1} [2] 3' | gojq '. as {$a} ?// [$a] ?// $a | $a'
1
2
3
 $ echo '{"foo": 4722366482869645213696}' | gojq .foo
4722366482869645213696  # keeps the precision of number while jq does not
 $ gojq -n 'def fact($n): if $n < 1 then 1 else $n * fact($n - 1) end; fact(50)'
30414093201713378043612608166064768844377641568960512000000000000 # arbitrary-precision integer calculation

Nice error messages.

 $ echo '[1,2,3]' | gojq  '.foo & .bar'
gojq: invalid query: .foo & .bar
    .foo & .bar
         ^  unexpected token "&"
 $ echo '{"foo": { bar: [] } }' | gojq '.'
gojq: invalid json: <stdin>
    {"foo": { bar: [] } }
              ^  invalid character 'b' looking for beginning of object key string

Installation

Homebrew
brew install gojq
Build from source
go get github.com/itchyny/gojq/cmd/gojq
Docker
docker run -i --rm itchyny/gojq

Difference to jq

  • gojq is purely implemented with Go language and is completely portable. jq depends on the C standard library so the availability of math functions depends on the library. jq also depends on the regular expression library and it makes build scripts complex.
  • gojq implements nice error messages for invalid query and JSON input. The error message of jq is sometimes difficult to tell where to fix the query.
  • gojq does not keep the order of object keys. I understand this might cause problems for some scripts but basically we should not rely on the order of object keys. I would implement when ordered map is implemented in the standard library of Go but I'm less motivated.
  • gojq supports arbitrary-precision integer calculation while jq does not. This is important to keeping the precision of numeric IDs or nanosecond values. You can use gojq to solve some mathematical problems which require big integers.
  • gojq supports reading from YAML input while jq does not. gojq also supports YAML output.

Usage as a library

You can use the gojq parser and interpreter from your Go products.

package main

import (
	"fmt"
	"log"

	"github.com/itchyny/gojq"
)

func main() {
	query, err := gojq.Parse(".foo | ..")
	if err != nil {
		log.Fatalln(err)
	}
	input := map[string]interface{}{"foo": []interface{}{1, 2, 3}}
	iter := query.Run(input) // or query.RunWithContext
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}
}
  • Firstly, use gojq.Parse(string) (*Query, error) to get the query from a string.
  • Secondly, get the result iterator
    • using query.Run or query.RunWithContext
    • or alternatively, compile the query using gojq.Compile and then code.Run or code.RunWithContext. You can reuse the *Code against multiple inputs to avoid compiling the same query.
    • In either case, the query input should have type []interface{} for an array and map[string]interface{} for a map (just like decoded to an interface{} using the encoding/json package). You can't use []int or map[string]string, for example.
  • Thirdly, iterate through the results using iter.Next() (interface{}, bool). The iterater can emit an error so make sure to handle it. Termination is notified by the second returned value of Next(). The reason why the return type is not (interface{}, error) is that the iterator can emit multiple errors and you can continue after an error.

gojq.Compile allows to configure the following compiler options.

  • gojq.WithModuleLoader allows to load modules. By default, the module feature is disabled. If you want to load modules from the filesystem, use gojq.NewModuleLoader.
  • gojq.WithEnvironLoader allows to configure the environment variables referenced by env and $ENV. By default, OS environment variables are not accessible due to security reason. You can use gojq.WithEnvironLoader(os.Environ) if you want.
  • gojq.WithVariables allows to configure the variables which can be used in the query. Pass the values of the variables to code.Run in the same order.
  • gojq.WithFunction allows to add a custom internal function.
  • gojq.WithInputIter allows to use input and inputs functions. By default, these functions are disabled.

Bug Tracker

Report bug at Issues・itchyny/gojq - GitHub.

Author

itchyny (https://github.com/itchyny)

License

This software is released under the MIT License, see LICENSE.

Expand ▾ Collapse ▴

Documentation

Overview

Package gojq provides the parser and interpreter of gojq.

Please refer to https://github.com/itchyny/gojq#usage-as-a-library for introduction of the usage as a library.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Marshal 

func Marshal(v interface{}) ([]byte, error)

Marshal returns the jq-flavored JSON encoding of v.

This method only accepts limited types (nil, bool, int, float64, *big.Int, string, []interface{} and map[string]interface{}) because these are the possible types a gojq iterator can emit. This method marshals NaN to null, truncates infinities to (+|-) math.MaxFloat64 and does not escape '<' and '>' for embedding in HTML. These behaviors are based on the marshaler of jq command and different from the standard library method json.Marshal.

Types

type Array 

type Array struct {
	Query *Query
}

Array ...

func (*Array) String 

func (e *Array) String() string

type Bind 

type Bind struct {
	Patterns []*Pattern
	Body     *Query
}

Bind ...

func (*Bind) String 

func (e *Bind) String() string

type Code 

type Code struct {
	// contains filtered or unexported fields
}

Code is a compiled jq query.

func Compile 

func Compile(q *Query, options ...CompilerOption) (*Code, error)

Compile compiles a query.

Example

Code:

package main

import (
	"fmt"
	"github.com/itchyny/gojq"
	"log"
)

func main() {
	query, err := gojq.Parse(".[] | .foo")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(query)
	if err != nil {
		log.Fatalln(err)
	}
	iter := code.Run([]interface{}{
		nil,
		"string",
		42,
		[]interface{}{"foo"},
		map[string]interface{}{"foo": 42},
	})
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			fmt.Println(err)
			continue
		}
		fmt.Printf("%#v\n", v)
	}

}

<nil>
expected an object but got: string ("string")
expected an object but got: number (42)
expected an object but got: array (["foo"])
42

func (*Code) Run 

func (c *Code) Run(v interface{}, values ...interface{}) Iter

Run runs the code with the variable values (which should be in the same order as the given variables using WithVariables) and returns a result iterator.

It is safe to call this method of a *Code in multiple goroutines.

Example

Code:

package main

import (
	"fmt"
	"github.com/itchyny/gojq"
	"log"
)

func main() {
	query, err := gojq.Parse(".foo")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(query)
	if err != nil {
		log.Fatalln(err)
	}
	input := map[string]interface{}{"foo": 42}
	iter := code.Run(input)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

42

func (*Code) RunWithContext 

func (c *Code) RunWithContext(ctx context.Context, v interface{}, values ...interface{}) Iter

RunWithContext runs the code with context.

Example

Code:

package main

import (
	"context"
	"fmt"
	"github.com/itchyny/gojq"
	"log"
	"time"
)

func main() {
	query, err := gojq.Parse("def f: f; f, f")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(query)
	if err != nil {
		log.Fatalln(err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()
	iter := code.RunWithContext(ctx, nil)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			fmt.Println(err)
			continue
		}
		_ = v
	}

}

context deadline exceeded

type CompilerOption 

type CompilerOption func(*compiler)

CompilerOption is a compiler option.

func WithEnvironLoader 

func WithEnvironLoader(environLoader func() []string) CompilerOption

WithEnvironLoader is a compiler option for environment variables loader. The OS environment variables are not accessible by default due to security reason. You can pass os.Environ if you allow to access it.

Example

Code:

package main

import (
	"fmt"
	"github.com/itchyny/gojq"
	"log"
)

func main() {
	query, err := gojq.Parse("env | keys[]")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(
		query,
		gojq.WithEnvironLoader(func() []string {
			return []string{"foo=42", "bar=128"}
		}),
	)
	if err != nil {
		log.Fatalln(err)
	}
	iter := code.Run(nil)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

"bar"
"foo"

func WithFunction 

func WithFunction(name string, minarity int, maxarity int,
	f func(interface{}, []interface{}) interface{}) CompilerOption

WithFunction is a compiler option for adding a custom internal function. Specify the minimum and maximum count of the function arguments. These values should satisfy 0 <= minarity <= maxarity <= 30, otherwise panics. On handling numbers, you should take account to int, float64 and *big.Int.

Example

Code:

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"math/big"
	"strconv"

	"github.com/itchyny/gojq"
)

func toFloat(x interface{}) (float64, bool) {
	switch x := x.(type) {
	case int:
		return float64(x), true
	case float64:
		return x, true
	case *big.Int:
		f, err := strconv.ParseFloat(x.String(), 64)
		return f, err == nil
	default:
		return 0.0, false
	}
}

func main() {
	query, err := gojq.Parse(".[] | f | f(3)")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(
		query,
		gojq.WithFunction("f", 0, 1, func(x interface{}, xs []interface{}) interface{} {
			if x, ok := toFloat(x); ok {
				if len(xs) == 1 {
					if y, ok := toFloat(xs[0]); ok {
						x *= y
					} else {
						return fmt.Errorf("f cannot be applied to: %v, %v", x, xs)
					}
				} else {
					x += 2
				}
				return x
			}
			return fmt.Errorf("f cannot be applied to: %v, %v", x, xs)
		}),
	)
	if err != nil {
		log.Fatalln(err)
	}
	input := []interface{}{0, 1, 2.5, json.Number("10000000000000000000000000000000000000000")}
	iter := code.Run(input)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

6
9
13.5
3e+40

func WithInputIter 

func WithInputIter(inputIter Iter) CompilerOption

WithInputIter is a compiler option for input iterator used by input(s)/0. Note that input and inputs functions are not allowed by default. We have to distinguish the query input and the values for input(s) functions. For example, consider using inputs with --null-input. If you want to allow input(s) functions, create an Iter and use WithInputIter option.

Example

Code:

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"strings"

	"github.com/itchyny/gojq"
)

type testInputIter struct {
	dec *json.Decoder
}

func newTestInputIter(r io.Reader) *testInputIter {
	dec := json.NewDecoder(r)
	dec.UseNumber()
	return &testInputIter{dec: dec}
}

func (i *testInputIter) Next() (interface{}, bool) {
	var v interface{}
	if err := i.dec.Decode(&v); err != nil {
		if err == io.EOF {
			return nil, false
		}
		return err, true
	}
	return v, true
}

func main() {
	query, err := gojq.Parse("reduce inputs as $x (0; . + $x)")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(
		query,
		gojq.WithInputIter(
			newTestInputIter(strings.NewReader("1 2 3 4 5")),
		),
	)
	if err != nil {
		log.Fatalln(err)
	}
	iter := code.Run(nil)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

15

func WithModuleLoader 

func WithModuleLoader(moduleLoader ModuleLoader) CompilerOption

WithModuleLoader is a compiler option for module loader. If you want to load modules from the filesystem, use NewModuleLoader.

Example

Code:

package main

import (
	"fmt"
	"log"

	"github.com/itchyny/gojq"
)

type moduleLoader struct{}

func (*moduleLoader) LoadModule(name string) (*gojq.Query, error) {
	switch name {
	case "module1":
		return gojq.Parse(`
			module { name: "module1", test: 42 };
			import "module2" as foo;
			def f: foo::f;
		`)
	case "module2":
		return gojq.Parse(`
			def f: .foo;
		`)
	}
	return nil, fmt.Errorf("module not found: %q", name)
}

func main() {
	query, err := gojq.Parse(`
		import "module1" as m;
		m::f
	`)
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(
		query,
		gojq.WithModuleLoader(&moduleLoader{}),
	)
	if err != nil {
		log.Fatalln(err)
	}
	input := map[string]interface{}{"foo": 42}
	iter := code.Run(input)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

42

func WithVariables 

func WithVariables(variables []string) CompilerOption

WithVariables is a compiler option for variable names. The variables can be used in the query. You have to give the values to query.Run or code.Run in the same order.

Example

Code:

package main

import (
	"fmt"
	"github.com/itchyny/gojq"
	"log"
)

func main() {
	query, err := gojq.Parse("$x * 100 + $y, $z")
	if err != nil {
		log.Fatalln(err)
	}
	code, err := gojq.Compile(
		query,
		gojq.WithVariables([]string{
			"$x", "$y", "$z",
		}),
	)
	if err != nil {
		log.Fatalln(err)
	}
	iter := code.Run(nil, 12, 42, 128)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

1242
128

type ConstArray 

type ConstArray struct {
	Elems []*ConstTerm
}

ConstArray ...

func (*ConstArray) String 

func (e *ConstArray) String() string

type ConstObject 

type ConstObject struct {
	KeyVals []*ConstObjectKeyVal
}

ConstObject ...

func (*ConstObject) String 

func (e *ConstObject) String() string

func (*ConstObject) ToValue 

func (e *ConstObject) ToValue() map[string]interface{}

ToValue converts the object to map[string]interface{}.

type ConstObjectKeyVal 

type ConstObjectKeyVal struct {
	Key       string
	KeyString string
	Val       *ConstTerm
}

ConstObjectKeyVal ...

func (*ConstObjectKeyVal) String 

func (e *ConstObjectKeyVal) String() string

type ConstTerm 

type ConstTerm struct {
	Object *ConstObject
	Array  *ConstArray
	Number string
	Str    string
	Null   bool
	True   bool
	False  bool
}

ConstTerm ...

func (*ConstTerm) String 

func (e *ConstTerm) String() string

type Foreach 

type Foreach struct {
	Term    *Term
	Pattern *Pattern
	Start   *Query
	Update  *Query
	Extract *Query
}

Foreach ...

func (*Foreach) String 

func (e *Foreach) String() string

type Func 

type Func struct {
	Name string
	Args []*Query
}

Func ...

func (*Func) String 

func (e *Func) String() string

type FuncDef 

type FuncDef struct {
	Name string
	Args []string
	Body *Query
}

FuncDef ...

func (*FuncDef) Minify 

func (e *FuncDef) Minify()

Minify ...

func (*FuncDef) String 

func (e *FuncDef) String() string

type If 

type If struct {
	Cond *Query
	Then *Query
	Elif []*IfElif
	Else *Query
}

If ...

func (*If) String 

func (e *If) String() string

type IfElif 

type IfElif struct {
	Cond *Query
	Then *Query
}

IfElif ...

func (*IfElif) String 

func (e *IfElif) String() string

type Import 

type Import struct {
	ImportPath  string
	ImportAlias string
	IncludePath string
	Meta        *ConstObject
}

Import ...

func (*Import) String 

func (e *Import) String() string

type Index 

type Index struct {
	Name    string
	Str     *String
	Start   *Query
	IsSlice bool
	End     *Query
}

Index ...

func (*Index) String 

func (e *Index) String() string

type Iter 

type Iter interface {
	Next() (interface{}, bool)
}

Iter is an interface for an iterator.

type Label 

type Label struct {
	Ident string
	Body  *Query
}

Label ...

func (*Label) String 

func (e *Label) String() string

type ModuleLoader 

type ModuleLoader interface {
}

ModuleLoader is an interface for loading modules.

Implement following optional methods. Use NewModuleLoader to load local modules. 

LoadModule(string) (*Query, error)
LoadModuleWithMeta(string, map[string]interface{}) (*Query, error)
LoadInitModules() ([]*Query, error)
LoadJSON(string) (interface{}, error)
LoadJSONWithMeta(string, map[string]interface{}) (interface{}, error)

func NewModuleLoader 

func NewModuleLoader(paths []string) ModuleLoader

NewModuleLoader creates a new ModuleLoader reading local modules in the paths.

type Object 

type Object struct {
	KeyVals []*ObjectKeyVal
}

Object ...

func (*Object) String 

func (e *Object) String() string

type ObjectKeyVal 

type ObjectKeyVal struct {
	Key           string
	KeyString     *String
	KeyQuery      *Query
	Val           *ObjectVal
	KeyOnly       string
	KeyOnlyString *String
}

ObjectKeyVal ...

func (*ObjectKeyVal) String 

func (e *ObjectKeyVal) String() string

type ObjectVal 

type ObjectVal struct {
	Queries []*Query
}

ObjectVal ...

func (*ObjectVal) String 

func (e *ObjectVal) String() string

type Operator 

type Operator int

Operator ... 

const (
	OpPipe Operator = iota + 1
	OpComma
	OpAdd
	OpSub
	OpMul
	OpDiv
	OpMod
	OpEq
	OpNe
	OpGt
	OpLt
	OpGe
	OpLe
	OpAnd
	OpOr
	OpAlt
	OpAssign
	OpModify
	OpUpdateAdd
	OpUpdateSub
	OpUpdateMul
	OpUpdateDiv
	OpUpdateMod
	OpUpdateAlt
)

Operators ...

func (Operator) GoString 

func (op Operator) GoString() (str string)

GoString implements GoStringer.

func (Operator) String 

func (op Operator) String() string

String implements Stringer.

type Pattern 

type Pattern struct {
	Name   string
	Array  []*Pattern
	Object []*PatternObject
}

Pattern ...

func (*Pattern) String 

func (e *Pattern) String() string

type PatternObject 

type PatternObject struct {
	Key       string
	KeyString *String
	KeyQuery  *Query
	Val       *Pattern
	KeyOnly   string
}

PatternObject ...

func (*PatternObject) String 

func (e *PatternObject) String() string

type Query 

type Query struct {
	Meta     *ConstObject
	Imports  []*Import
	FuncDefs []*FuncDef
	Term     *Term
	Left     *Query
	Op       Operator
	Right    *Query
	Func     string
}

Query represents the abstract syntax tree of a jq query.

func Parse 

func Parse(src string) (*Query, error)

line parser.go.y:2 Parse parses a query.

func (*Query) Run 

func (e *Query) Run(v interface{}) Iter

Run the query.

It is safe to call this method of a *Query in multiple goroutines.

Example

Code:

package main

import (
	"fmt"
	"github.com/itchyny/gojq"
	"log"
)

func main() {
	query, err := gojq.Parse(".foo | ..")
	if err != nil {
		log.Fatalln(err)
	}
	input := map[string]interface{}{"foo": []interface{}{1, 2, 3}}
	iter := query.Run(input)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			log.Fatalln(err)
		}
		fmt.Printf("%#v\n", v)
	}

}

[]interface {}{1, 2, 3}
1
2
3

func (*Query) RunWithContext 

func (e *Query) RunWithContext(ctx context.Context, v interface{}) Iter

RunWithContext runs the query with context.

Example

Code:

package main

import (
	"context"
	"fmt"
	"github.com/itchyny/gojq"
	"log"
	"time"
)

func main() {
	query, err := gojq.Parse("def f: f; f, f")
	if err != nil {
		log.Fatalln(err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()
	iter := query.RunWithContext(ctx, nil)
	for {
		v, ok := iter.Next()
		if !ok {
			break
		}
		if err, ok := v.(error); ok {
			fmt.Println(err)
			continue
		}
		_ = v
	}

}

context deadline exceeded

func (*Query) String 

func (e *Query) String() string

type Reduce 

type Reduce struct {
	Term    *Term
	Pattern *Pattern
	Start   *Query
	Update  *Query
}

Reduce ...

func (*Reduce) String 

func (e *Reduce) String() string

type String 

type String struct {
	Str     string
	Queries []*Query
}

String ...

func (*String) String 

func (e *String) String() string

type Suffix 

type Suffix struct {
	Index    *Index
	Iter     bool
	Optional bool
	Bind     *Bind
}

Suffix ...

func (*Suffix) String 

func (e *Suffix) String() string

type Term 

type Term struct {
	Type       TermType
	Index      *Index
	Func       *Func
	Object     *Object
	Array      *Array
	Number     string
	Unary      *Unary
	Format     string
	Str        *String
	If         *If
	Try        *Try
	Reduce     *Reduce
	Foreach    *Foreach
	Label      *Label
	Break      string
	Query      *Query
	SuffixList []*Suffix
}

Term ...

func (*Term) String 

func (e *Term) String() string

type TermType 

type TermType int

TermType represents the type of Term. 

const (
	TermTypeIdentity TermType = iota + 1
	TermTypeRecurse
	TermTypeNull
	TermTypeTrue
	TermTypeFalse
	TermTypeIndex
	TermTypeFunc
	TermTypeObject
	TermTypeArray
	TermTypeNumber
	TermTypeUnary
	TermTypeFormat
	TermTypeString
	TermTypeIf
	TermTypeTry
	TermTypeReduce
	TermTypeForeach
	TermTypeLabel
	TermTypeBreak
	TermTypeQuery
)

TermType list.

func (TermType) GoString 

func (termType TermType) GoString() (str string)

GoString implements GoStringer.

type Try 

type Try struct {
	Body  *Query
	Catch *Query
}

Try ...

func (*Try) String 

func (e *Try) String() string

type Unary 

type Unary struct {
	Op   Operator
	Term *Term
}

Unary ...

func (*Unary) String 

func (e *Unary) String() string

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Path Synopsis
cli
cmd/gojq