--- /dev/null
+package main
+
+type dbConfig struct {
+ user, pass, dbName string
+}
+
+func getConfig() dbConfig {
+ // TODO: use a real password, and load config info from a file
+ return dbConfig{user:"quanlib", pass:"quanlib", dbName:"quanlib"}
+}
--- /dev/null
+package main
+
+import (
+ "database/sql"
+ "fmt"
+ _ "github.com/lib/pq"
+ "strconv"
+ "sync"
+)
+
+// ---------------------------------------------------------------------------
+type Book struct {
+ Id int
+ Age string // recommended age, e.g. "beginner", "junior", "ya" (Young Adult), "adult"
+ AuthorGrouping string // unique rendering of the author's name, used for internal grouping
+ AuthorReading string // reading order of author's name, e.g. "Charles Dickens"
+ AuthorSort string // sort order of author's name, e.g. "Dickens, Charles"
+ DDC string // Dewey Decimal Classification
+ Description string // Back cover / inside flap blurb, describing the book
+ Genre string // e.g. "adventure", "historical", "mystery", "romance", "sf" (Science Fiction)
+ LCC string // Library of Congress Classification
+ SeriesName string
+ Title string
+ Volume string
+}
+
+// ---------------------------------------------------------------------------
+type Field string
+const (
+ Author, Series, Title Field = "aut", "ser", "tit"
+)
+
+func (f Field) String() string {
+ return string(f)
+}
+
+// ---------------------------------------------------------------------------
+type SearchTerm struct {
+ Attribute Field
+ Text string
+}
+
+var g_db *sql.DB = nil
+var g_mutex = &sync.Mutex{}
+
+// ============================================================================
+func dbShutdown() {
+ if nil != g_db {
+ g_db.Close()
+ }
+}
+
+func getDb() (*sql.DB) {
+ if nil == g_db {
+ g_mutex.Lock()
+ defer g_mutex.Unlock()
+ if nil == g_db {
+ config := getConfig()
+ g_db = openDb(config.user, config.pass, config.dbName)
+ }
+ }
+
+ return g_db
+}
+
+func nsVal(ns sql.NullString) string {
+ if ns.Valid {
+ return ns.String
+ }
+ return ""
+}
+
+func openDb(user, pass, dbName string) (*sql.DB) {
+ db, err := sql.Open("postgres","user=" + user + " password=" + pass + " dbname=" + dbName + " sslmode=disable")
+ if nil != err {
+ report("Error: DB arguments incorrect?", err)
+ return nil
+ }
+
+ err = db.Ping()
+ if nil != err {
+ report("Error: could not connect to DB.", err)
+ db.Close()
+ return nil
+ }
+
+ return db
+}
+
+func queryBooksByIds(ids []int) []Book {
+ query := `SELECT s.age,a.grouping,a.reading,a.sort,c.ddc,b.description,s.genre,c.lcc,s.descr,b.title,b.volume
+ FROM Authors a
+ INNER JOIN Books b ON a.id=b.author
+ LEFT OUTER JOIN Classifications c ON c.id=b.classification
+ LEFT OUTER JOIN Series s ON s.id=b.series
+ WHERE b.id=$1`
+
+ ps, err := getDb().Prepare(query)
+ if nil != err {
+ report("Error: failed to prepare statement: " + query, err)
+ return nil
+ }
+ defer ps.Close()
+
+ var count int = 0
+ for _, id := range ids {
+ if 0 != id {
+ count++
+ }
+ }
+
+ res := make([]Book, count)
+
+ count = 0
+ for _, id := range ids {
+ if 0 == id {
+ continue
+ }
+
+ row := ps.QueryRow(id)
+
+ var age, grouping, reading, sort, ddc, description, genre, lcc, name, title, volume sql.NullString
+
+ err = row.Scan(&age, &grouping, &reading, &sort, &ddc, &description, &genre, &lcc, &name, &title, &volume)
+ if err != nil {
+ report("Error: Failed to read book:" + strconv.Itoa(id) + ":", err)
+ } else {
+ var b Book
+ b.Id = id
+ b.Age = nsVal(age)
+ b.AuthorGrouping = nsVal(grouping)
+ b.AuthorReading = nsVal(reading)
+ b.AuthorSort = nsVal(sort)
+ b.DDC = nsVal(ddc)
+ b.Description = nsVal(description)
+ b.Genre = nsVal(genre)
+ b.LCC = nsVal(lcc)
+ b.SeriesName = nsVal(name)
+ b.Title = nsVal(title)
+ b.Volume = nsVal(volume)
+
+ res[count] = b
+ count++
+ }
+ }
+
+ if count < len(res) {
+ res = res[:count]
+ }
+
+ return res
+}
+
+func queryIds(criteria []SearchTerm) []int {
+ query := "SELECT b.id FROM Books b" +
+ " INNER JOIN Authors a ON a.id=b.author" +
+ " LEFT OUTER JOIN Series s ON s.id=b.series"
+
+ args := make([]interface{}, len(criteria))
+
+ for i, criterion := range criteria {
+ if 0 == i {
+ query += " WHERE "
+ } else {
+ query += " AND "
+ }
+ switch criterion.Attribute {
+ case Author:
+ query += " a.grouping LIKE $" + strconv.Itoa(i + 1)
+ case Series:
+ query += " s.descr LIKE $" + strconv.Itoa(i + 1)
+ case Title:
+ query += " b.title LIKE $" + strconv.Itoa(i + 1)
+ default:
+ report("Error: unrecognized search field in queryIds(): " + criterion.Attribute.String(), nil)
+ return nil
+ }
+ args[i] = criterion.Text
+ }
+
+ res := []int{}
+
+ ps, err := getDb().Prepare(query)
+ if nil != err {
+ report("Failed to Prepare query: " + query, err)
+ return nil
+ }
+ defer ps.Close()
+
+ var rows *sql.Rows
+ rows, err = ps.Query(args...)
+ if nil != err {
+ report("Failed to execute query: " + query, err)
+ return nil
+ }
+ defer rows.Close()
+
+ for rows.Next(); rows.Next(); {
+ var id int
+ rows.Scan(&id)
+ res = append(res, id)
+ }
+
+ return res
+}
+
+func report(msg string, err error) {
+ fmt.Println("Error: " + msg, err)
+}
--- /dev/null
+package main
+
+import (
+ "encoding/json"
+ "fmt"
+ "net/http"
+ "strconv"
+ "strings"
+)
+
+const PARAM_IDS = "ids"
+const MAX_TERMS = 10
+
+// ============================================================================
+func handler(w http.ResponseWriter, r *http.Request) {
+ err := r.ParseForm()
+ if nil != err {
+ fmt.Fprintln(w, "ERROR!", err)
+ return
+ }
+
+ action := r.URL.Path[1:]
+
+ switch(action) {
+ case "info":
+ handleInfo(w, r)
+ case "search":
+ handleSearch(w, r)
+ default:
+ fmt.Fprintf(w, "Unrecognized request: %s\n", r.URL.Path[1:])
+ fmt.Fprintf(w, "id: %s\n", r.FormValue("id"))
+
+ fmt.Fprintln(w, "URL: ", r.URL)
+ fmt.Fprintln(w, "Query: ", r.URL.Query())
+ }
+}
+
+func handleInfo(w http.ResponseWriter, r *http.Request) {
+ idParams := r.Form[PARAM_IDS]
+ if 1 != len(idParams) {
+ fmt.Fprintln(w, "ERROR! Detected either zero or multiple ids= parameters. Exactly one expected.")
+ return
+ }
+
+ idParam := idParams[0]
+ idStrings := strings.Split(idParam, ",")
+ ids := make([]int, len(idStrings))
+ for i, v := range(idStrings) {
+ var err error
+ ids[i], err = strconv.Atoi(v)
+ if nil != err {
+ ids[i] = 0
+ }
+ }
+
+ books := queryBooksByIds(ids)
+
+ var jsonValue []byte
+ var err error
+ jsonValue, err = json.Marshal(books)
+ if nil != err {
+ fmt.Fprintln(w, "ERROR!", err)
+ } else {
+ w.Write(jsonValue)
+ }
+}
+
+func handleSearch(w http.ResponseWriter, r *http.Request) {
+ fields := []Field{Author, Title, Series}
+
+ terms := make([]SearchTerm, len(fields))
+
+ count := 0
+ for _, fv := range(fields) {
+ paramName := fv.String()
+ paramValues := r.Form[paramName]
+ for _, pv := range(paramValues) {
+ if count >= len(terms) {
+ fmt.Printf("WARNING: limit of %v search terms exceeded. One or more terms ignored.")
+ break
+ }
+ terms[count] = SearchTerm{Attribute:fv, Text:pv}
+ count++
+ }
+ }
+
+ terms = terms[:count]
+
+ ids := queryIds(terms)
+
+ jsonValue, err := json.Marshal(ids)
+ if nil != err {
+ fmt.Fprintln(w, "ERROR!", err)
+ } else {
+ w.Write(jsonValue)
+ }
+}
import (
"database/sql"
- "fmt"
- _ "github.com/lib/pq"
-// "json"
+ "net/http"
)
-type Book struct {
- Id int
- Age string // recommended age, e.g. "beginner", "junior", "ya" (Young Adult), "adult"
- AuthorGrouping string // unique rendering of the author's name, used for internal grouping
- AuthorReading string // reading order of author's name, e.g. "Charles Dickens"
- AuthorSort string // sort order of author's name, e.g. "Dickens, Charles"
- DDC string // Dewey Decimal Classification
- Description string // Back cover / inside flap blurb, describing the book
- Genre string // e.g. "adventure", "historical", "mystery", "romance", "sf" (Science Fiction)
- LCC string // Library of Congress Classification
- SeriesName string
- Title string
- Volume string
-}
-
+// ============================================================================
func main() {
- // TODO: protect DB with a real password, and read DB config from an external file
- db := openDb("quanlib", "quanlib", "quanlib")
- if nil == db {
- return
- }
- defer db.Close()
-
- query := "SELECT COUNT(1) FROM Books"
- ps, err := db.Prepare(query)
- if nil != err {
- fmt.Println("Error: failed to prepare statement: " + query)
- return
- }
-
- var count int
- err = ps.QueryRow().Scan(&count)
- if sql.ErrNoRows == err {
- fmt.Println("Error: No rows returned by statement: " + query)
- } else {
- fmt.Println("Found ", count, " books.")
- }
-
- ids := []int {1041, 1951, 2148, 103}
- books := queryBooksByIds(db, ids)
-
- fmt.Println("Found books:", books)
-}
-
-func nsVal(ns sql.NullString) string {
- if ns.Valid {
- return ns.String
- }
- return ""
-}
-
-func openDb(user, pass, dbName string) (*sql.DB) {
- db, err := sql.Open("postgres","user=" + user + " password=" + pass + " dbname=" + dbName + " sslmode=disable")
- if nil != err {
- fmt.Println("Error: DB arguments incorrect?", err)
- return nil
- }
+ defer dbShutdown()
- err = db.Ping()
- if nil != err {
- fmt.Println("Error: could not connect to DB.", err)
- db.Close()
- return nil
- }
+ var b sql.NullString
+ nsVal(b)
- return db
+ http.HandleFunc("/", handler)
+ http.ListenAndServe(":8001", nil)
}
-
-func queryBooksByIds(db *sql.DB, ids []int) []Book {
- query := `SELECT s.age,a.grouping,a.reading,a.sort,c.ddc,b.description,s.genre,c.lcc,s.descr,b.title,b.volume
- FROM Authors a
- INNER JOIN Books b ON a.id=b.author
- LEFT OUTER JOIN Classifications c ON c.id=b.classification
- LEFT OUTER JOIN Series s ON s.id=b.series
- WHERE b.id=$1`
-
- ps, err := db.Prepare(query)
- if nil != err {
- fmt.Println("Error: failed to prepare statement: " + query)
- return nil
- }
- defer ps.Close()
-
- res := make([]Book, len(ids))
-
- for n, id := range ids {
- row := ps.QueryRow(id)
-
- var age, grouping, reading, sort, ddc, description, genre, lcc, name, title, volume sql.NullString
-
- err = row.Scan(&age, &grouping, &reading, &sort, &ddc, &description, &genre, &lcc, &name, &title, &volume)
- if err != nil {
- fmt.Println("Error: Failed to read book:", id, ":", err)
- } else {
- var b Book
- b.Id = id
- b.Age = nsVal(age)
- b.AuthorGrouping = nsVal(grouping)
- b.AuthorReading = nsVal(reading)
- b.AuthorSort = nsVal(sort)
- b.DDC = nsVal(ddc)
- b.Description = nsVal(description)
- b.Genre = nsVal(genre)
- b.LCC = nsVal(lcc)
- b.SeriesName = nsVal(name)
- b.Title = nsVal(title)
- b.Volume = nsVal(volume)
-
- res[n] = b
- }
- }
-
- return res
-}
-
projects / quanweb.git / commitdiff