refactor(firestore): [PQ] Combine FieldOf and FieldOfPath

firestore/pipeline.go

@@ -166,8 +166,8 @@ func (p *Pipeline) Offset(offset int) *Pipeline {
 //
 //		client.Pipeline().Collection("users").Select("info.email")
 //		client.Pipeline().Collection("users").Select(FieldOf("info.email"))
-//		client.Pipeline().Collection("users").Select(FieldOfPath([]string{"info", "email"}))
-//		client.Pipeline().Collection("users").Select(FieldOfPath([]string{"info", "email"}))
+//		client.Pipeline().Collection("users").Select(FieldOf([]string{"info", "email"}))
+//		client.Pipeline().Collection("users").Select(FieldOf([]string{"info", "email"}))
 //	 	client.Pipeline().Collection("users").Select(Add("age", 5).As("agePlus5"))
 func (p *Pipeline) Select(fieldpathsOrSelectables ...any) *Pipeline {
 	if p.err != nil {
@@ -341,7 +341,7 @@ func (p *Pipeline) UnnestWithAlias(fieldpath any, alias string, opts *UnnestOpti
 	case string:
 		fieldExpr = FieldOf(v)
 	case FieldPath:
-		fieldExpr = FieldOfPath(v)
+		fieldExpr = FieldOf(v)
 	default:
 		p.err = errInvalidArg(fieldpath, "string", "FieldPath")
 		return p

firestore/pipeline_aggregate.go

@@ -44,7 +44,7 @@ func newBaseAggregateFunction(name string, fieldOrExpr any) *baseAggregateFuncti
 		case string:
 			valueExpr = FieldOf(value)
 		case FieldPath:
-			valueExpr = FieldOfPath(value)
+			valueExpr = FieldOf(value)
 		case Expr:
 			valueExpr = value
 		default:

firestore/pipeline_field.go

@@ -29,20 +29,22 @@ type field struct {
 }
 
 // FieldOf creates a new field [Expr] from a field path string.
-func FieldOf(path string) Expr {
-	fieldPath, err := parseDotSeparatedString(path)
-	if err != nil {
-		return &field{baseExpr: &baseExpr{err: err}}
+func FieldOf[T string | FieldPath](path T) Expr {
+	anyPath := any(path)
+	var fieldPath FieldPath
+	var err error
+	if v, ok := anyPath.(string); ok {
+		fieldPath, err = parseDotSeparatedString(v)
+		if err != nil {
+			return &field{baseExpr: &baseExpr{err: err}}
+		}
+	} else {
+		fieldPath = anyPath.(FieldPath)
 	}
-	return FieldOfPath(fieldPath)
-}
 
-// FieldOfPath creates a new field [Expr] for the given [FieldPath].
-func FieldOfPath(fieldPath FieldPath) Expr {
 	if err := fieldPath.validate(); err != nil {
 		return &field{baseExpr: &baseExpr{err: err}}
 	}
-
 	pbVal := &pb.Value{
 		ValueType: &pb.Value_FieldReferenceValue{
 			FieldReferenceValue: fieldPath.toServiceFieldPath(),

firestore/pipeline_integration_test.go

@@ -868,10 +868,10 @@ func aggregateFuncs(t *testing.T) {
 			want: map[string]interface{}{"sum_a": int64(3)},
 		},
 		{
-			name: "Sum - FieldOfPath Expr",
+			name: "Sum - FieldOf Path Expr",
 			pipeline: client.Pipeline().
 				Collection(coll.ID).
-				Aggregate(Sum(FieldOfPath(FieldPath([]string{"a"}))).As("sum_a")),
+				Aggregate(Sum(FieldOf(FieldPath([]string{"a"}))).As("sum_a")),
 			want: map[string]interface{}{"sum_a": int64(3)},
 		},
 		{

firestore/pipeline_stage.go

@@ -213,7 +213,7 @@ func newFindNearestStage(vectorField any, queryVector any, measure PipelineDista
 	case string:
 		propertyExpr = FieldOf(v)
 	case FieldPath:
-		propertyExpr = FieldOfPath(v)
+		propertyExpr = FieldOf(v)
 	case Expr:
 		propertyExpr = v
 	default:
@@ -300,7 +300,7 @@ func newRemoveFieldsStage(fieldpaths ...any) (*removeFieldsStage, error) {
 		case string:
 			fields[i] = FieldOf(v)
 		case FieldPath:
-			fields[i] = FieldOfPath(v)
+			fields[i] = FieldOf(v)
 		default:
 			return nil, errInvalidArg(fp, "string", "FieldPath")
 		}
@@ -332,7 +332,7 @@ func newReplaceStage(fieldOrSelectable any) (*replaceStage, error) {
 	case string:
 		expr = FieldOf(v)
 	case FieldPath:
-		expr = FieldOfPath(v)
+		expr = FieldOf(v)
 	case Selectable:
 		_, expr = v.getSelectionDetails()
 	default:
@@ -463,7 +463,7 @@ func newUnnestStage(fieldExpr Expr, alias string, opts *UnnestOptions) (*unnestS
 		var indexFieldExpr Expr
 		switch v := opts.IndexField.(type) {
 		case FieldPath:
-			indexFieldExpr = FieldOfPath(v)
+			indexFieldExpr = FieldOf(v)
 		case string:
 			indexFieldExpr = FieldOf(v)
 		default:

firestore/pipeline_utils.go

@@ -117,7 +117,7 @@ func asFieldExpr(val any) Expr {
 	case Expr:
 		return v
 	case FieldPath:
-		return FieldOfPath(v)
+		return FieldOf(v)
 	case string:
 		return FieldOf(v)
 	default:
@@ -191,7 +191,7 @@ func fieldsOrSelectablesToSelectables(fieldsOrSelectables ...any) ([]Selectable,
 			}
 			s = FieldOf(v).(*field)
 		case FieldPath:
-			s = FieldOfPath(v).(*field)
+			s = FieldOf(v).(*field)
 		case Selectable:
 			s = v
 		default: