forked from apache/beam
/
main.go
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/
main.go
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// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// beam-playground:
// name: side-inputs
// description: Side-inputs example.
// multifile: false
// context_line: 41
// categories:
// - Quickstart
// complexity: MEDIUM
// tags:
// - hellobeam
package main
import (
"context"
"github.com/apache/beam/sdks/v2/go/pkg/beam"
"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
"github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
"github.com/apache/beam/sdks/v2/go/pkg/beam/x/debug"
)
type Person struct {
Name, City, Country string
}
func main() {
ctx := context.Background()
p, s := beam.NewPipelineWithRoot()
// List of elements
citiesToCountriesKV := beam.ParDo(s, func(_ []byte, emit func(string, string)) {
emit("Beijing", "China")
emit("London", "United Kingdom")
emit("San Francisco", "United States")
emit("Singapore", "Singapore")
emit("Sydney", "Australia")
}, beam.Impulse(s))
persons := beam.Create(s,
Person{Name: "Henry", City: "Singapore"},
Person{Name: "Jane", City: "San Francisco"},
Person{Name: "Lee", City: "Beijing"},
Person{Name: "John", City: "Sydney"},
Person{Name: "Alfred", City: "London"},
)
// The applyTransform() converts [input] to [output]
output := applyTransform(s, persons, citiesToCountriesKV)
debug.Print(s, output)
err := beamx.Run(ctx, p)
if err != nil {
log.Exitf(context.Background(), "Failed to execute job: %v", err)
}
}
// Create from citiesToCountries view "citiesToCountriesView" and used in ParDo
func applyTransform(s beam.Scope, personsKV beam.PCollection, citiesToCountries beam.PCollection) beam.PCollection {
citiesToCountriesView := beam.SideInput{
Input: citiesToCountries,
}
return beam.ParDo(s, joinFn, personsKV, citiesToCountriesView)
}
// Compares cities and unites
func joinFn(person Person, citiesToCountriesIter func(*string, *string) bool, emit func(Person)) {
var city, country string
for citiesToCountriesIter(&city, &country) {
if person.City == city {
emit(Person{
Name: person.Name,
City: city,
Country: country,
})
break
}
}
}