Checks whether an uploaded filename ends with ".pdf" before routing it to the PDF parser.
package main
import (
"context"
"encoding/json"
"log"
"os"
"time"
"github.com/akennis/sparsi-go/library"
_ "github.com/akennis/dagor/operator/builtin"
"github.com/panjf2000/ants/v2"
"github.com/akennis/dagor"
"github.com/akennis/dagor/graph"
)
func main() {
filename, suffix := "report_2026.pdf", ".pdf"
library.RegisterConst("filename_val", filename)
library.RegisterConst("suffix_val", suffix)
g, err := graph.NewBuilder("hassuffix_demo").
Vertex("src_a").Op("filename_val").Output("Result", "wire_a").
Vertex("src_b").Op("suffix_val").Output("Result", "wire_b").
Vertex("check").Op("IfStringHasSuffixOp").
Input("A", "wire_a").Input("B", "wire_b").
Output("Match", "is_pdf").
Build()
if err != nil {
log.Fatalf("build: %v", err)
}
pool, err := ants.NewPool(4)
if err != nil {
log.Fatalf("pool: %v", err)
}
defer pool.Release()
eng, err := dagor.NewEngine(g, pool)
if err != nil {
log.Fatalf("engine: %v", err)
}
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
defer cancel()
if err := eng.Run(ctx); err != nil {
log.Fatalf("run: %v", err)
}
out := map[string]any{"filename": filename, "suffix": suffix}
if raw, ok := eng.GetOutput("is_pdf"); ok {
out["is_pdf"] = *raw.(*bool)
}
enc := json.NewEncoder(os.Stdout)
enc.SetIndent("", " ")
enc.Encode(out)
}