feat: generalize context omission to json

textlog.go

@@ -30,9 +30,10 @@ type TextlogValuePair struct {
 type TextlogFormatter struct {
 	// FormatValue is a function that formats a single value into a string. If it is nil, fmt.Sprint is used.
 	FormatValue func(data any, modifiers []string) string
-	// Omit is a function that determines whether a field should be omitted from the log entry.
+	// Omit is a function that determines whether a struct field should be omitted from the log entry.
+	// It receives the full struct field (including all of its tags) and the field's value.
 	// If it is nil, no fields are omitted.
-	Omit func(modifiers []string, value any) bool
+	Omit func(field reflect.StructField, value any) bool
 }
 
 func (t TextlogFormatter) format(data any, modifiers []string) string {
@@ -121,7 +122,7 @@ func (t TextlogFormatter) toEntry(object reflect.Value) TextlogEntry {
 			if slices.Contains(tagModifiers, TextlogModifierOmitempty) && isZero(field) {
 				continue
 			}
-			if t.Omit != nil && t.Omit(tagModifiers, field.Interface()) {
+			if t.Omit != nil && t.Omit(typeField, field.Interface()) {
 				continue
 			}
 			if typeField.Anonymous || slices.Contains(tagModifiers, TextlogModifierExpand) {

textlog_test.go

@@ -2,6 +2,7 @@ package jsonlog
 
 import (
 	"fmt"
+	"reflect"
 	"testing"
 	"time"
 
@@ -88,3 +89,32 @@ func TestTextlogFormatting(t *testing.T) {
 		{"MAP_KEY", "map"},
 	}, details)
 }
+
+func TestTextlogOmit(t *testing.T) {
+	type omitTestObject struct {
+		Kept    string `json:"kept" textlog:"kept"`
+		Omitted string `json:"omitted" textlog:"omitted" context:"omit"`
+		Nested  struct {
+			Omitted string `json:"omitted" textlog:"omitted" context:"omit"`
+			Kept    int    `json:"kept" textlog:"kept"`
+		} `json:"nested" textlog:"nested,expand"`
+	}
+	var test omitTestObject
+	test.Kept = "kept"
+	test.Omitted = "omitted"
+	test.Nested.Omitted = "omitted"
+	test.Nested.Kept = 42
+
+	formatter := TextlogFormatter{
+		FormatValue: func(data any, modifiers []string) string {
+			return "formatted:" + fmt.Sprint(data)
+		},
+		Omit: func(field reflect.StructField, value any) bool {
+			return field.Tag.Get("context") == "omit"
+		},
+	}
+	assert.Equal(t, TextlogEntry{
+		{"KEPT", "formatted:kept"},
+		{"NESTED_KEPT", "formatted:42"},
+	}, formatter.Format(test))
+}

thorlog/v3/event.go

@@ -10,7 +10,6 @@ import (
 	"github.com/NextronSystems/jsonlog"
 	"github.com/NextronSystems/jsonlog/jsonpointer"
 	"github.com/NextronSystems/jsonlog/thorlog/common"
-	"golang.org/x/exp/slices"
 )
 
 // Assessment is a summary of a Subject's analysis by THOR.
@@ -157,16 +156,7 @@ func (a *Ancestor) UnmarshalJSON(data []byte) error {
 }
 
 func (a Ancestors) MarshalTextLog(t jsonlog.TextlogFormatter) jsonlog.TextlogEntry {
-	oldOmit := t.Omit
-	t.Omit = func(modifiers []string, value any) bool {
-		if slices.Contains(modifiers, omitInContext) {
-			return true // Omit fields that are marked with "omitincontext"
-		}
-		if oldOmit != nil {
-			return oldOmit(modifiers, value) // Call the original omit function if it exists
-		}
-		return false // Default behavior is to not omit any fields
-	}
+	t = withOmitInContext(t)
 	var result jsonlog.TextlogEntry
 	for _, ancestor := range a {
 		var prefix string
@@ -193,7 +183,22 @@ type Derivative struct {
 	Object ObservedObject `json:"object" textlog:",expand"`
 }
 
-const omitInContext = "omitincontext"
+// withOmitInContext returns a formatter that additionally omits all fields tagged with `context:"omit"`.
+// This tag marks fields that are too verbose to be repeated for an object that is only
+// logged as context (ancestor or derivative) of another object.
+func withOmitInContext(t jsonlog.TextlogFormatter) jsonlog.TextlogFormatter {
+	oldOmit := t.Omit
+	t.Omit = func(field reflect.StructField, value any) bool {
+		if field.Tag.Get("context") == "omit" {
+			return true
+		}
+		if oldOmit != nil {
+			return oldOmit(field, value)
+		}
+		return false
+	}
+	return t
+}
 
 func (d *Derivative) UnmarshalJSON(data []byte) error {
 	type plainDerivative Derivative
@@ -214,16 +219,7 @@ func (d *Derivative) UnmarshalJSON(data []byte) error {
 }
 
 func (d Derivative) MarshalTextLog(t jsonlog.TextlogFormatter) jsonlog.TextlogEntry {
-	oldOmit := t.Omit
-	t.Omit = func(modifiers []string, value any) bool {
-		if slices.Contains(modifiers, omitInContext) {
-			return true // Omit fields that are marked with "omitincontext"
-		}
-		if oldOmit != nil {
-			return oldOmit(modifiers, value) // Call the original omit function if it exists
-		}
-		return false // Default behavior is to not omit any fields
-	}
+	t = withOmitInContext(t)
 	type plainDerivative Derivative // Wrap this struct to not implement TextlogMarshaler
 	return t.Format(plainDerivative(d))
 }

thorlog/v3/registry.go

@@ -11,7 +11,7 @@ type RegistryValue struct {
 
 	Key         string    `json:"key" textlog:"key"`
 	Modified    time.Time `json:"modified" textlog:"modified"`
-	ParsedValue string    `json:"value" textlog:"value,omitincontext"`
+	ParsedValue string    `json:"value" textlog:"value" context:"omit"`
 	Size        uint64    `json:"size" textlog:"size"`
 }
 
@@ -33,7 +33,7 @@ type RegistryKey struct {
 	jsonlog.ObjectHeader
 	Key             string    `json:"key" textlog:"key"`
 	Modified        time.Time `json:"modified" textlog:"modified"`
-	FormattedValues string    `json:"values" textlog:"values,omitincontext"`
+	FormattedValues string    `json:"values" textlog:"values" context:"omit"`
 }
 
 func (RegistryKey) observed() {}