/
jmespath.go
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/
jmespath.go
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package processor
import (
"encoding/json"
"fmt"
"time"
"github.com/Jeffail/benthos/v3/internal/docs"
"github.com/Jeffail/benthos/v3/internal/tracing"
"github.com/Jeffail/benthos/v3/lib/log"
"github.com/Jeffail/benthos/v3/lib/metrics"
"github.com/Jeffail/benthos/v3/lib/types"
jmespath "github.com/jmespath/go-jmespath"
)
//------------------------------------------------------------------------------
func init() {
Constructors[TypeJMESPath] = TypeSpec{
constructor: NewJMESPath,
Categories: []Category{
CategoryMapping,
},
Summary: `
Executes a [JMESPath query](http://jmespath.org/) on JSON documents and replaces
the message with the resulting document.`,
Description: `
:::note Try out Bloblang
For better performance and improved capabilities try out native Benthos mapping with the [bloblang processor](/docs/components/processors/bloblang).
:::
`,
Examples: []docs.AnnotatedExample{
{
Title: "Mapping",
Summary: `
When receiving JSON documents of the form:
` + "```json" + `
{
"locations": [
{"name": "Seattle", "state": "WA"},
{"name": "New York", "state": "NY"},
{"name": "Bellevue", "state": "WA"},
{"name": "Olympia", "state": "WA"}
]
}
` + "```" + `
We could collapse the location names from the state of Washington into a field ` + "`Cities`" + `:
` + "```json" + `
{"Cities": "Bellevue, Olympia, Seattle"}
` + "```" + `
With the following config:`,
Config: `
pipeline:
processors:
- jmespath:
query: "locations[?state == 'WA'].name | sort(@) | {Cities: join(', ', @)}"
`,
},
},
FieldSpecs: docs.FieldSpecs{
docs.FieldCommon("query", "The JMESPath query to apply to messages."),
PartsFieldSpec,
},
}
}
//------------------------------------------------------------------------------
// JMESPathConfig contains configuration fields for the JMESPath processor.
type JMESPathConfig struct {
Parts []int `json:"parts" yaml:"parts"`
Query string `json:"query" yaml:"query"`
}
// NewJMESPathConfig returns a JMESPathConfig with default values.
func NewJMESPathConfig() JMESPathConfig {
return JMESPathConfig{
Parts: []int{},
Query: "",
}
}
//------------------------------------------------------------------------------
// JMESPath is a processor that executes JMESPath queries on a message part and
// replaces the contents with the result.
type JMESPath struct {
parts []int
query *jmespath.JMESPath
conf Config
log log.Modular
stats metrics.Type
mCount metrics.StatCounter
mErrJSONP metrics.StatCounter
mErrJMES metrics.StatCounter
mErrJSONS metrics.StatCounter
mErr metrics.StatCounter
mSent metrics.StatCounter
mBatchSent metrics.StatCounter
}
// NewJMESPath returns a JMESPath processor.
func NewJMESPath(
conf Config, mgr types.Manager, log log.Modular, stats metrics.Type,
) (Type, error) {
query, err := jmespath.Compile(conf.JMESPath.Query)
if err != nil {
return nil, fmt.Errorf("failed to compile JMESPath query: %v", err)
}
j := &JMESPath{
parts: conf.JMESPath.Parts,
query: query,
conf: conf,
log: log,
stats: stats,
mCount: stats.GetCounter("count"),
mErrJSONP: stats.GetCounter("error.json_parse"),
mErrJMES: stats.GetCounter("error.jmespath_search"),
mErrJSONS: stats.GetCounter("error.json_set"),
mErr: stats.GetCounter("error"),
mSent: stats.GetCounter("sent"),
mBatchSent: stats.GetCounter("batch.sent"),
}
return j, nil
}
//------------------------------------------------------------------------------
func safeSearch(part interface{}, j *jmespath.JMESPath) (res interface{}, err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("jmespath panic: %v", r)
}
}()
return j.Search(part)
}
// JMESPath doesn't like json.Number so we walk the tree and replace them.
func clearNumbers(v interface{}) (interface{}, bool) {
switch t := v.(type) {
case map[string]interface{}:
for k, v := range t {
if nv, ok := clearNumbers(v); ok {
t[k] = nv
}
}
case []interface{}:
for i, v := range t {
if nv, ok := clearNumbers(v); ok {
t[i] = nv
}
}
case json.Number:
f, err := t.Float64()
if err != nil {
if i, err := t.Int64(); err == nil {
return i, true
}
}
return f, true
}
return nil, false
}
// ProcessMessage applies the processor to a message, either creating >0
// resulting messages or a response to be sent back to the message source.
func (p *JMESPath) ProcessMessage(msg types.Message) ([]types.Message, types.Response) {
p.mCount.Incr(1)
newMsg := msg.Copy()
proc := func(index int, span *tracing.Span, part types.Part) error {
jsonPart, err := part.JSON()
if err != nil {
p.mErrJSONP.Incr(1)
p.mErr.Incr(1)
p.log.Debugf("Failed to parse part into json: %v\n", err)
return err
}
if v, replace := clearNumbers(jsonPart); replace {
jsonPart = v
}
var result interface{}
if result, err = safeSearch(jsonPart, p.query); err != nil {
p.mErrJMES.Incr(1)
p.mErr.Incr(1)
p.log.Debugf("Failed to search json: %v\n", err)
return err
}
if err = newMsg.Get(index).SetJSON(result); err != nil {
p.mErrJSONS.Incr(1)
p.mErr.Incr(1)
p.log.Debugf("Failed to convert jmespath result into part: %v\n", err)
return err
}
return nil
}
IteratePartsWithSpanV2(TypeJMESPath, p.parts, newMsg, proc)
msgs := [1]types.Message{newMsg}
p.mBatchSent.Incr(1)
p.mSent.Incr(int64(newMsg.Len()))
return msgs[:], nil
}
// CloseAsync shuts down the processor and stops processing requests.
func (p *JMESPath) CloseAsync() {
}
// WaitForClose blocks until the processor has closed down.
func (p *JMESPath) WaitForClose(timeout time.Duration) error {
return nil
}
//------------------------------------------------------------------------------