fix: xpath fails to parse json array elements

plugins/parsers/xpath/json_document.go

@@ -1,23 +1,38 @@
 package xpath
 
 import (
-	"reflect"
+	"bytes"
+	"encoding/json"
+	"fmt"
 	"strconv"
-	"strings"
 
-	"github.com/antchfx/jsonquery"
 	path "github.com/antchfx/xpath"
+	"github.com/fxamacker/cbor/v2"
+	"github.com/srebhan/cborquery"
 )
 
 type jsonDocument struct{}
 
 func (*jsonDocument) Parse(buf []byte) (dataNode, error) {
-	return jsonquery.Parse(strings.NewReader(string(buf)))
+	// First parse JSON to an interface{}
+	var data interface{}
+	if err := json.Unmarshal(buf, &data); err != nil {
+		return nil, fmt.Errorf("failed to parse JSON: %w", err)
+	}
+
+	// Convert to CBOR to leverage cborquery's correct array handling
+	cborData, err := cbor.Marshal(data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to convert JSON to CBOR: %w", err)
+	}
+
+	// Parse with cborquery which handles arrays correctly
+	return cborquery.Parse(bytes.NewReader(cborData))
 }
 
 func (*jsonDocument) QueryAll(node dataNode, expr string) ([]dataNode, error) {
 	// If this panics it's a programming error as we changed the document type while processing
-	native, err := jsonquery.QueryAll(node.(*jsonquery.Node), expr)
+	native, err := cborquery.QueryAll(node.(*cborquery.Node), expr)
 	if err != nil {
 		return nil, err
 	}
@@ -31,15 +46,15 @@ func (*jsonDocument) QueryAll(node dataNode, expr string) ([]dataNode, error) {
 
 func (*jsonDocument) CreateXPathNavigator(node dataNode) path.NodeNavigator {
 	// If this panics it's a programming error as we changed the document type while processing
-	return jsonquery.CreateXPathNavigator(node.(*jsonquery.Node))
+	return cborquery.CreateXPathNavigator(node.(*cborquery.Node))
 }
 
 func (d *jsonDocument) GetNodePath(node, relativeTo dataNode, sep string) string {
 	names := make([]string, 0)
 
 	// If these panic it's a programming error as we changed the document type while processing
-	nativeNode := node.(*jsonquery.Node)
-	nativeRelativeTo := relativeTo.(*jsonquery.Node)
+	nativeNode := node.(*cborquery.Node)
+	nativeRelativeTo := relativeTo.(*cborquery.Node)
 
 	// Climb up the tree and collect the node names
 	n := nativeNode.Parent
@@ -64,40 +79,41 @@ func (d *jsonDocument) GetNodePath(node, relativeTo dataNode, sep string) string
 
 func (d *jsonDocument) GetNodeName(node dataNode, sep string, withParent bool) string {
 	// If this panics it's a programming error as we changed the document type while processing
-	nativeNode := node.(*jsonquery.Node)
+	nativeNode := node.(*cborquery.Node)
 
-	name := nativeNode.Data
+	name := nativeNode.Name
 
-	// Check if the node is part of an array. If so, determine the index and
-	// concatenate the parent name and the index.
-	kind := reflect.Invalid
-	if nativeNode.Parent != nil && nativeNode.Parent.Value() != nil {
-		kind = reflect.TypeOf(nativeNode.Parent.Value()).Kind()
-	}
-
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		// Determine the index for array elements
-		if name == "" && nativeNode.Parent != nil && withParent {
-			name = nativeNode.Parent.Data + sep
+	// In cborquery, array elements appear as siblings with the same name.
+	// Check if this node is part of an array by looking for siblings with the same name.
+	if nativeNode.Parent != nil && name != "" {
+		idx, count := d.siblingIndex(nativeNode)
+		if count > 1 {
+			// This is an array element, append the index
+			return name + sep + strconv.Itoa(idx)
 		}
-		return name + d.index(nativeNode)
 	}
 
 	return name
 }
 
 func (*jsonDocument) OutputXML(node dataNode) string {
-	native := node.(*jsonquery.Node)
+	native := node.(*cborquery.Node)
 	return native.OutputXML()
 }
 
-func (*jsonDocument) index(node *jsonquery.Node) string {
-	idx := 0
-
-	for n := node; n.PrevSibling != nil; n = n.PrevSibling {
-		idx++
+func (*jsonDocument) siblingIndex(node *cborquery.Node) (idx, count int) {
+	if node.Parent == nil {
+		return 0, 1
 	}
 
-	return strconv.Itoa(idx)
+	// Count siblings with the same name and find our index among them
+	for sibling := node.Parent.FirstChild; sibling != nil; sibling = sibling.NextSibling {
+		if sibling.Name == node.Name {
+			if sibling == node {
+				idx = count
+			}
+			count++
+		}
+	}
+	return idx, count
 }

plugins/parsers/xpath/msgpack_document.go

@@ -2,23 +2,39 @@ package xpath
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 
-	"github.com/antchfx/jsonquery"
 	path "github.com/antchfx/xpath"
+	"github.com/fxamacker/cbor/v2"
+	"github.com/srebhan/cborquery"
 	"github.com/tinylib/msgp/msgp"
 )
 
 type msgpackDocument jsonDocument
 
 func (*msgpackDocument) Parse(buf []byte) (dataNode, error) {
-	var json bytes.Buffer
+	var jsonBuf bytes.Buffer
 
-	// Unmarshal the message-pack binary message to JSON and proceed with the jsonquery class
-	if _, err := msgp.UnmarshalAsJSON(&json, buf); err != nil {
+	// Unmarshal the message-pack binary message to JSON
+	if _, err := msgp.UnmarshalAsJSON(&jsonBuf, buf); err != nil {
 		return nil, fmt.Errorf("unmarshalling to json failed: %w", err)
 	}
-	return jsonquery.Parse(&json)
+
+	// Parse JSON to interface{}
+	var data interface{}
+	if err := json.Unmarshal(jsonBuf.Bytes(), &data); err != nil {
+		return nil, fmt.Errorf("failed to parse JSON: %w", err)
+	}
+
+	// Convert to CBOR to leverage cborquery's correct array handling
+	cborData, err := cbor.Marshal(data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to convert JSON to CBOR: %w", err)
+	}
+
+	// Parse with cborquery which handles arrays correctly
+	return cborquery.Parse(bytes.NewReader(cborData))
 }
 
 func (d *msgpackDocument) QueryAll(node dataNode, expr string) ([]dataNode, error) {

plugins/parsers/xpath/parser.go

@@ -11,7 +11,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/antchfx/jsonquery"
 	path "github.com/antchfx/xpath"
 	"github.com/srebhan/cborquery"
 	"github.com/srebhan/protobufquery"
@@ -493,8 +492,6 @@ func (p *Parser) executeQuery(doc, selected dataNode, query string) (r interface
 			switch nn := current.(type) {
 			case *cborquery.NodeNavigator:
 				return nn.GetValue(), nil
-			case *jsonquery.NodeNavigator:
-				return nn.GetValue(), nil
 			case *protobufquery.NodeNavigator:
 				return nn.GetValue(), nil
 			}
@@ -562,10 +559,18 @@ func (p *Parser) constructFieldName(root, node dataNode, name string, expand boo
 
 	// In case the name is empty we should determine the current node's name.
 	// This involves array index expansion in case the parent of the node is
-	// and array. If we expanded here, we should skip our parent as this is
-	// already encoded in the name
+	// an array. If we expanded here, we should skip our parent as this is
+	// already encoded in the name.
 	if name == "" {
 		name = p.document.GetNodeName(node, "_", !expand)
+	} else {
+		// For non-empty names, check if this is an array element and append index.
+		// GetNodeName returns the name with array index for array elements.
+		nodeName := p.document.GetNodeName(node, "_", false)
+		if nodeName != name && strings.Contains(nodeName, name+"_") {
+			// The node name includes an array index (e.g., "cpus_0" vs "cpus")
+			name = nodeName
+		}
 	}
 
 	// If name expansion is requested, construct a path between the current

plugins/parsers/xpath/parser_test.go

@@ -1604,7 +1604,7 @@ const benchmarkDataJSON = `
 `
 
 var benchmarkConfigJSON = Config{
-	Selection: "data/*",
+	Selection: "//data",
 	Tags: map[string]string{
 		"tags_host":     "tags_host",
 		"tags_sdkver":   "tags_sdkver",

plugins/parsers/xpath/testcases/json_array_indexing/expected.out

@@ -0,0 +1 @@
+nvme,device=/dev/nvme1,model_name=Samsung\ SSD,serial_number=ABC123 ns1_capacity=960197124096i,ns1_id=1i,ns1_utilization=86638583808i,ns2_capacity=500107862016i,ns2_id=2i

plugins/parsers/xpath/testcases/json_array_indexing/telegraf.conf

@@ -0,0 +1,21 @@
+[[inputs.file]]
+  files = ["./testcases/json_array_indexing/test.json"]
+  data_format = "xpath_json"
+
+  xpath_native_types = true
+
+  [[inputs.file.xpath]]
+    metric_name = "'nvme'"
+
+    [inputs.file.xpath.tags]
+      device = "string(/device/name)"
+      model_name = "string(/model_name)"
+      serial_number = "string(/serial_number)"
+
+    [inputs.file.xpath.fields_int]
+      # Test accessing array elements by index - this is the fix for issue #18145
+      ns1_id = "number(//nvme_namespaces[1]/id)"
+      ns1_capacity = "number(//nvme_namespaces[1]/capacity/bytes)"
+      ns1_utilization = "number(//nvme_namespaces[1]/utilization/bytes)"
+      ns2_id = "number(//nvme_namespaces[2]/id)"
+      ns2_capacity = "number(//nvme_namespaces[2]/capacity/bytes)"

plugins/parsers/xpath/testcases/json_array_indexing/test.json

@@ -0,0 +1,27 @@
+{
+  "device": {
+    "name": "/dev/nvme1"
+  },
+  "model_name": "Samsung SSD",
+  "serial_number": "ABC123",
+  "nvme_namespaces": [
+    {
+      "id": 1,
+      "capacity": {
+        "bytes": 960197124096
+      },
+      "utilization": {
+        "bytes": 86638583808
+      }
+    },
+    {
+      "id": 2,
+      "capacity": {
+        "bytes": 500107862016
+      },
+      "utilization": {
+        "bytes": 42949672960
+      }
+    }
+  ]
+}

plugins/parsers/xpath/testcases/json_explicit_precedence/expected.out

@@ -1 +1 @@
-foo a="a string",b=3.1415,c=true,d="{\"d1\":1,\"d2\":\"foo\",\"d3\":true,\"d4\":null}",e="[\"master\",42,true]",timestamp=1690193829 1690193829000000000
+foo a="a string",b=3.1415,c=true,d="map[d1:1 d2:foo d3:true d4:<nil>]",e="master",e_0="master",e_1=42,e_2=true,timestamp=1690193829 1690193829000000000

plugins/parsers/xpath/testcases/json_native_nonnested/expected.out

@@ -1 +1 @@
-foo a="a string",b=3.1415,c=true,d="map[d1:1 d2:foo d3:true d4:<nil>]",e="[master 42 true]",timestamp=1690193829 1690193829000000000
+foo a="a string",b=3.1415,c=true,d="map[d1:1 d2:foo d3:true d4:<nil>]",e_0="master",e_1=42,e_2=true,timestamp=1690193829 1690193829000000000

plugins/parsers/xpath/testcases/json_string_representation/expected.out

@@ -1 +1 @@
-foo a="a string",b="3.1415",c="true",d="{\"d1\":1,\"d2\":\"foo\",\"d3\":true,\"d4\":null}",e="[\"master\",42,true]",timestamp="1690193829" 1690193829000000000
+foo a="a string",b="3.1415",c="true",d="map[d1:1 d2:foo d3:true d4:<nil>]",e_0="master",e_1="42",e_2="true",timestamp="1.690193829e+09" 1690193829000000000

plugins/parsers/xpath/testcases/name_expansion/telegraf.conf

@@ -5,6 +5,6 @@
 
   [[inputs.file.xpath]]
     metric_name = "'devices'"
-    metric_selection = "/devices/*"
+    metric_selection = "//devices"
     field_selection = "descendant::*[not(*)]"
     field_name_expansion = true

plugins/parsers/xpath/testcases/openweathermap_json.conf

@@ -10,7 +10,7 @@
 #
 
 metric_name = "'weather'"
-metric_selection = "//list/*"
+metric_selection = "//list"
 timestamp = "dt"
 timestamp_format = "unix"
 

plugins/parsers/xpath/testcases/string_join/telegraf.conf

@@ -10,4 +10,4 @@
     timestamp_format = "unix"
 
     [inputs.file.xpath.fields]
-      cpus = "string-join(//cpus/*, ';')"
+      cpus = "string-join(//cpus, ';')"

plugins/parsers/xpath/testcases/tracker_msgpack.conf

@@ -20,5 +20,5 @@ timestamp_format = "unix"
 
 [fields]
   serial = "info/serial_number"
-  lat = "number(/geo/*[1])"
-  lon = "number(/geo/*[2])"
+  lat = "number(//geo[1])"
+  lon = "number(//geo[2])"