From 1e111eed2500db175ac4c2132822276485e4b4a4 Mon Sep 17 00:00:00 2001
From: Martin Czygan <martin.czygan@gmail.com>
Date: Wed, 28 Apr 2021 23:28:48 +0200
Subject: simplify fixed field extractor

---
 skate/go.mod |  1 +
 skate/go.sum |  6 ++++++
 skate/map.go | 35 ++++-------------------------------
 3 files changed, 11 insertions(+), 31 deletions(-)

diff --git a/skate/go.mod b/skate/go.mod
index bd2093a..49ef5d2 100644
--- a/skate/go.mod
+++ b/skate/go.mod
@@ -9,5 +9,6 @@ require (
 	github.com/miku/parallel v0.0.0-20210205190127-d1fa15dcea0c
 	github.com/nsf/jsondiff v0.0.0-20210303162244-6ea32392771e
 	github.com/segmentio/encoding v0.2.17
+	github.com/tidwall/gjson v1.7.5
 	golang.org/x/text v0.3.5
 )
diff --git a/skate/go.sum b/skate/go.sum
index 61baedb..a186bcd 100644
--- a/skate/go.sum
+++ b/skate/go.sum
@@ -12,6 +12,12 @@ github.com/nsf/jsondiff v0.0.0-20210303162244-6ea32392771e h1:S+/ptYdZtpK/MDstwC
 github.com/nsf/jsondiff v0.0.0-20210303162244-6ea32392771e/go.mod h1:uFMI8w+ref4v2r9jz+c9i1IfIttS/OkmLfrk1jne5hs=
 github.com/segmentio/encoding v0.2.17 h1:cgfmPc44u1po1lz5bSgF00gLCROBjDNc7h+H7I20zpc=
 github.com/segmentio/encoding v0.2.17/go.mod h1:7E68jTSWMnNoYhHi1JbLd7NBSB6XfE4vzqhR88hDBQc=
+github.com/tidwall/gjson v1.7.5 h1:zmAN/xmX7OtpAkv4Ovfso60r/BiCi5IErCDYGNJu+uc=
+github.com/tidwall/gjson v1.7.5/go.mod h1:5/xDoumyyDNerp2U36lyolv46b3uF/9Bu6OfyQ9GImk=
+github.com/tidwall/match v1.0.3 h1:FQUVvBImDutD8wJLN6c5eMzWtjgONK9MwIBCOrUJKeE=
+github.com/tidwall/match v1.0.3/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.1.0 h1:K3hMW5epkdAVwibsQEfR/7Zj0Qgt4DxtNumTq/VloO8=
+github.com/tidwall/pretty v1.1.0/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
 golang.org/x/text v0.3.5 h1:i6eZZ+zk0SOf0xgBpEpPD18qWcJda6q1sxt3S0kzyUQ=
 golang.org/x/text v0.3.5/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/skate/map.go b/skate/map.go
index 5584371..9d3c98d 100644
--- a/skate/map.go
+++ b/skate/map.go
@@ -5,10 +5,10 @@ import (
 	"errors"
 	"reflect"
 	"runtime"
-	"strconv"
 	"strings"
 
 	json "github.com/segmentio/encoding/json"
+	"github.com/tidwall/gjson"
 )
 
 var (
@@ -47,7 +47,7 @@ func (f Mapper) AsTSV(p []byte) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return append(bytes.Join(fields, bTab), bNewline...), nil
+	return bytes.Join(fields, bTab), nil
 }
 
 // WithPrefix adds a given prefix to the first element.
@@ -84,36 +84,9 @@ func Identity(p []byte) ([][]byte, error) {
 // CreateFixedMapper extract the value from a given fixed top level json key.
 // Returns a function that maps doc to (v, doc).
 func CreateFixedMapper(field string) Mapper {
-	if field == "" {
-		return func(p []byte) ([][]byte, error) {
-			return nil, ErrMissingFieldName
-		}
-	}
 	f := func(p []byte) ([][]byte, error) {
-		var (
-			doc map[string]interface{}
-			v   interface{}
-			ok  bool
-			key []byte
-		)
-		if err := json.Unmarshal(p, &doc); err != nil {
-			return nil, err
-		}
-		if v, ok = doc[field]; !ok {
-			return nil, nil
-		}
-		switch w := v.(type) {
-		case string:
-			key = []byte(w)
-		case int:
-			key = []byte(strconv.Itoa(w))
-		case int64:
-			key = []byte(strconv.Itoa(int(w)))
-		case float64:
-			key = []byte(strconv.FormatFloat(w, 'f', 52, 64))
-		default:
-			return nil, nil
-		}
+		result := gjson.GetBytes(p, field)
+		key := []byte(result.String())
 		return [][]byte{key, p}, nil
 	}
 	return f
-- 
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