Added sqlite DB to cache translations; retrieve translations from DB if they're cached, otherwise fetch from API and cache results

golangServer/testing.go

@@ -2,17 +2,49 @@ package main
 
 import (
 	"context"
+	"database/sql"
 	"encoding/json"
 	"fmt"
 	"log"
 	"net/http"
 
+	"github.com/jmoiron/sqlx"
+	_ "github.com/mattn/go-sqlite3"
+
 	translate "cloud.google.com/go/translate/apiv3"
 	"cloud.google.com/go/translate/apiv3/translatepb"
 )
 
 const project_id string = "india-translate-testing-452100"
 
+type translationStruct struct {
+	En       string `db:"english" json:"en"`
+	Hi       string `db:"hindi" json:"hi"`
+	Bn       string `db:"bengali" json:"bn"`
+	Mr       string `db:"marathi" json:"mr"`
+	Ta       string `db:"tamil" json:"ta"`
+	Te       string `db:"telugu" json:"te"`
+	Ml       string `db:"malayalam" json:"ml"`
+	Kn       string `db:"kannada" json:"kn"`
+	Gu       string `db:"gujarati" json:"gu"`
+	Or       string `db:"oriya" json:"or"`
+	Ur       string `db:"urdu" json:"ur"`
+	Lus      string `db:"mizo" json:"lus"`
+	As       string `db:"assamese" json:"as"`
+	Pa       string `db:"punjabi" json:"pa"`
+	Mai      string `db:"maithili" json:"nai"`
+	Mwr      string `db:"marwari" json:"mwr"`
+	Sat      string `db:"santali" json:"sat"`
+	Ne       string `db:"nepali" json:"ne"`
+	Gom      string `db:"konkani" json:"gom"`
+	Tcy      string `db:"tulu" json:"tcy"`
+	Bho      string `db:"bhojpuri" json:"bho"`
+	Doi      string `db:"dogri" json:"doi"`
+	Mni_mtei string `db:"manipuri" json:"mni_mtei"`
+	Sd       string `db:"sindhi" json:"sd"`
+	Awa      string `db:"awadhi" json:"awa"`
+}
+
 var lang_codes []string = []string{
 	"hi",       // Hindi
 	"bn",       // Bengali
@@ -40,6 +72,39 @@ var lang_codes []string = []string{
 	"awa",      // Awadhi
 }
 
+var db *sqlx.DB
+
+/*
+	Returns the cached translation from the database, for the given english text. The first parameter
+
+indicates whether or not the translation exists.
+*/
+func getCachedTranslation(data string) (bool, translationStruct) {
+	prepared, err := db.Preparex("SELECT * from TRANSLATIONS WHERE english = ? COLLATE NOCASE")
+	if err != nil {
+		panic(err)
+	}
+
+	translations := translationStruct{}
+	err = prepared.Get(&translations, data)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return false, translations
+		} else {
+			panic(err)
+		}
+	} else {
+		return true, translations
+	}
+}
+
+func addToDatabase(translation translationStruct) {
+	_, err := db.NamedExec(`INSERT INTO translations VALUES (:english, :hindi, :bengali, :marathi, :tamil, :telugu, :kannada, :malayalam, :oriya, :gujarati, :marwari, :urdu, :mizo, :assamese, :punjabi, :maithili, :santali, :nepali, :konkani, :tulu, :bhojpuri, :dogri, :manipuri, :sindhi, :awadhi)`, &translation)
+	if err != nil {
+		panic(err)
+	}
+}
+
 func translateText(text string, targetLang string) (result string, err error) {
 	return translateTextHelper(project_id, "en-US", targetLang, text)
 }
@@ -80,22 +145,39 @@ func handler(w http.ResponseWriter, r *http.Request) {
 	queries := r.URL.Query()
 	toTranslate := queries["query"][0]
 
-	langToTranslation := make(map[string]string)
-	for _, lang_code := range lang_codes {
-		translation, err := translateText(toTranslate, lang_code)
+	if ok, translation := getCachedTranslation(toTranslate); ok {
+		translationJson, _ := json.Marshal(translation)
+		fmt.Fprintf(w, "%v", string(translationJson))
+	} else {
+		langToTranslation := make(map[string]string)
+		for _, lang_code := range lang_codes {
+			translation, err := translateText(toTranslate, lang_code)
+			if err != nil {
+				panic(err)
+			}
+			langToTranslation[lang_code] = translation
+		}
+		langToTranslationJson, _ := json.Marshal(langToTranslation)
+		translation := translationStruct{}
+		err := json.Unmarshal(langToTranslationJson, &translation)
+		translation.En = toTranslate // langToTranslation doesn't contain the english value
+		addToDatabase(translation)
 		if err != nil {
 			panic(err)
 		}
-		langToTranslation[lang_code] = translation
+		fmt.Fprintf(w, "%v", string(langToTranslationJson))
 	}
-
-	langToTranslationJson, _ := json.Marshal(langToTranslation)
-	fmt.Fprintf(w, "%v", string(langToTranslationJson))
-
-	// fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
 }
 
 func main() {
+	fmt.Printf("Starting server...")
+	var err error
+	db, err = sqlx.Connect("sqlite3", "translations.db")
+	if err != nil {
+		panic(err)
+	}
+	defer db.Close()
+
 	http.HandleFunc("/", handler)
 	log.Fatal(http.ListenAndServe(":9090", nil))
 }