← Library SliceDeterministic

SliceFilterEqOp

Filters a string slice, retaining only elements equal to a given value.

Inputs

FieldTypeDescription
Input*[]stringSlice to filter
Value*stringValue to keep

Outputs

FieldTypeDescription
Result[]stringElements equal to Value

Typical Use Cases

  • Filtering a result list to a specific label
  • Counting occurrences of a value in a slice
  • Deduplication step before downstream processing

Complete Runnable Example

Filters a list of ticket statuses to keep only the "open" ones for downstream processing.

main.go
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() {
	statuses := []string{"open", "closed", "open", "pending", "open"}
	filter := "open"
	library.RegisterConst("statuses_val", statuses)
	library.RegisterConst("filter_val", filter)

	g, err := graph.NewBuilder("filtereq_demo").
		Vertex("src").Op("statuses_val").Output("Result", "wire_in").
		Vertex("flt").Op("filter_val").Output("Result", "wire_val").
		Vertex("fil").Op("SliceFilterEqOp").
		Input("Input", "wire_in").Input("Value", "wire_val").
		Output("Result", "filtered").
		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{"statuses": statuses, "filter": filter}
	if raw, ok := eng.GetOutput("filtered"); ok {
		out["open_tickets"] = *raw.(*[]string)
	}
	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	enc.Encode(out)
}