add some examples

Author: Stefan Tudose

data/simple.csv

@@ -0,0 +1,3 @@
+john,44,true
+lucy,48,false
+mr hyde,34,true

example_custom_decoder_test.go

@@ -0,0 +1,66 @@
+package csvdecoder_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/stefantds/csvdecoder"
+)
+
+type Point struct {
+	X int
+	Y int
+}
+
+// DecodeRecord implements the csvdecoder.Interface type
+func (p *Point) DecodeRecord(record string) error {
+	// the decode code is specific to the way the object is serialized.
+	// in this example the point is encoded as a JSON array with two values
+
+	data := make([]int, 2)
+	if err := json.NewDecoder(strings.NewReader(record)).Decode(&data); err != nil {
+		return fmt.Errorf("could not parse %s as JSON array: %w", record, err)
+	}
+
+	(*p).X = data[0]
+	(*p).Y = data[1]
+
+	return nil
+}
+
+func Example_custom_decoder() {
+	// the csv separator is a semicolon in this example
+	exampleData := strings.NewReader(
+		`[0, 0];[0, 2];[1, 2]
+[-1, 2];[0, -2];[1, 0]
+`)
+
+	// create a new decoder that will read from the given file
+	decoder, err := csvdecoder.NewWithConfig(exampleData, csvdecoder.Config{Comma: ';'})
+	if err != nil {
+		// handle error
+		return
+	}
+
+	// iterate over the rows in the file
+	for decoder.Next() {
+		var a, b, c Point
+
+		// scan the first values to the types
+		if err := decoder.Scan(&a, &b, &c); err != nil {
+			// handle error
+			return
+		}
+		fmt.Printf("a: %v, b: %v, c: %v\n", a, b, c)
+	}
+
+	// check if the loop stopped prematurely because of an error
+	if err = decoder.Err(); err != nil {
+		// handle error
+		return
+	}
+
+	// Output: a: {0 0}, b: {0 2}, c: {1 2}
+	// a: {-1 2}, b: {0 -2}, c: {1 0}
+}

example_simple_test.go

@@ -0,0 +1,57 @@
+package csvdecoder_test
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/stefantds/csvdecoder"
+)
+
+type User struct {
+	Name   string
+	Active bool
+	Age    int
+}
+
+func Example_simple() {
+
+	// the csv file contains the values:
+	//john,44,true
+	//lucy,48,false
+	//mr hyde,34,true
+	file, err := os.Open("./data/simple.csv")
+	if err != nil {
+		// handle error
+		return
+	}
+	defer file.Close()
+
+	// create a new decoder that will read from the given file
+	decoder, err := csvdecoder.New(file)
+	if err != nil {
+		// handle error
+		return
+	}
+
+	// iterate over the rows in the file
+	for decoder.Next() {
+		var u User
+
+		// scan the first three values in the name, age and active fields respectively
+		if err := decoder.Scan(&u.Name, &u.Age, &u.Active); err != nil {
+			// handle error
+			return
+		}
+		fmt.Println(u)
+	}
+
+	// check if the loop stopped prematurely because of an error
+	if err = decoder.Err(); err != nil {
+		// handle error
+		return
+	}
+
+	// Output: {john true 44}
+	// {lucy false 48}
+	// {mr hyde true 34}
+}

example_slices_test.go

@@ -0,0 +1,62 @@
+package csvdecoder_test
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/stefantds/csvdecoder"
+)
+
+type MyStringCollection []string
+
+// DecodeRecord implements the csvdecoder.Interface type
+func (c *MyStringCollection) DecodeRecord(record string) error {
+	// the decode code is specific to the way the value is serialized.
+	// in this example the array is represented as int values separated by space
+	*c = MyStringCollection(strings.Split(record, " "))
+
+	return nil
+}
+
+func Example_slices() {
+	// the csv separator is a semicolon in this example
+	// the values are arrays serialized in two different ways.
+	exampleData := strings.NewReader(
+		`jon;elvis boris ahmed jane;["jo", "j"]
+jane;lucas george;["j", "jay"]
+`)
+
+	// create a new decoder that will read from the given file
+	decoder, err := csvdecoder.NewWithConfig(exampleData, csvdecoder.Config{Comma: ';'})
+	if err != nil {
+		// handle error
+		return
+	}
+
+	type Person struct {
+		Name      string
+		Friends   MyStringCollection
+		Nicknames []string
+	}
+
+	// iterate over the rows in the file
+	for decoder.Next() {
+		var p Person
+
+		// scan the first values to the types
+		if err := decoder.Scan(&p.Name, &p.Friends, &p.Nicknames); err != nil {
+			// handle error
+			return
+		}
+		fmt.Printf("%v\n", p)
+	}
+
+	// check if the loop stopped prematurely because of an error
+	if err = decoder.Err(); err != nil {
+		// handle error
+		return
+	}
+
+	// Output: {jon [elvis boris ahmed jane] [jo j]}
+	// {jane [lucas george] [j jay]}
+}