skate: move out helper function

1 files changed, 25 insertions, 0 deletions

diff --git a/skate/cluster.go b/skate/cluster.go
index 7fc4e1b..3421a0b 100644
--- a/skate/cluster.go
+++ b/skate/cluster.go
@@ -1,6 +1,7 @@
 package skate
 
 import (
+	"fmt"
 	"regexp"
 	"strings"
 
@@ -109,6 +110,30 @@ func KeyTitleSandcrawler(p []byte) (ident string, key string, err error) {
 	return ident, sandcrawlerSlugify(key), nil
 }
 
+// CreateFixedFieldFunc creates an extractor function given a json path.
+// Currently only top level key is supported.
+func CreateFixedFieldFunc(path string) IdentifierKeyFunc {
+	f := func(p []byte) (ident string, key string, err error) {
+		var doc map[string]interface{}
+		if err = json.Unmarshal(p, &doc); err != nil {
+			return
+		}
+		v, ok := doc[path]
+		if !ok {
+			return "", "", nil
+		}
+		switch t := v.(type) {
+		case string:
+			return "", t, nil
+		case int, int64, float32, float64:
+			return "", fmt.Sprintf("%v", t), nil
+		default:
+			return "", "", nil
+		}
+	}
+	return f
+}
+
 // sandcrawlerSlugify normalizes a string.
 func sandcrawlerSlugify(s string) string {
 	slug := strings.ToLower(strings.TrimSpace(s))