func HackerNewsPostScraper(sub string) (err error) {
//drivername := "postgres"
//dsn := "user=golang password=golang dbname=golang sslmode=disable"
//dialect := gorp.PostgresDialect{}
drivername := "mysql"
dsn := "golang:golang@/golang?parseTime=true"
dialect := gorp.MySQLDialect{"InnoDB", "utf8mb4"}
// connect to db using standard Go database/sql API
db, err := sql.Open(drivername, dsn)
if err != nil {
return errors.New("sql.Open failed: " + err.Error())
}
// Open doesn't open a connection. Validate DSN data using ping
if err = db.Ping(); err != nil {
return errors.New("db.Ping failed: " + err.Error())
}
// Set the connection to use utf8bmb4
if dialect.Engine == "InnoDB" {
fmt.Println("Setting connection to utf8mb4")
_, err = db.Exec("SET NAMES utf8mb4 COLLATE utf8mb4_general_ci")
if err != nil {
return errors.New("SET NAMES utf8mb4 COLLATE utf8mb4_general_ci: " + err.Error())
}
}
// construct a gorp DbMap
dbmap := &gorp.DbMap{Db: db, Dialect: dialect}
defer dbmap.Db.Close()
dbmap.DebugLevel = DebugLevel
// Will log all SQL statements + args as they are run
// The first arg is a string prefix to prepend to all log messages
//dbmap.TraceOn("[gorp]", log.New(os.Stdout, "Trace:", log.Lmicroseconds))
// register the structs you wish to use with gorp
// you can also use the shorter dbmap.AddTable() if you
// don't want to override the table name
// SetKeys(true) means we have a auto increment primary key, which
// will get automatically bound to your struct post-insert
table := dbmap.AddTableWithName(post.Post{}, "posts_index_test")
table.SetKeys(true, "PID")
// Add the comments table
table = dbmap.AddTableWithName(post.Comment{}, "comments_index_test")
table.SetKeys(true, "Id")
// create the table. in a production system you'd generally
// use a migration tool, or create the tables via scripts
if err = dbmap.CreateTablesIfNotExists(); err != nil {
return errors.New("Create tables failed: " + err.Error())
}
// Force create all indexes for this database
if err = dbmap.CreateIndexes(); err != nil {
return errors.New("Create indexes failed: " + err.Error())
}
// Get data from hackernews
geturl := "http://news.ycombinator.com/" + sub
// DEBUG for a special thread
//geturl := "https://news.ycombinator.com/item?id=10056146"
body, err := GetHtmlBody(geturl)
if err != nil {
return errors.New("GetHtmlBody: " + err.Error())
}
// Create a new post slice and then parse the response body into ps
ps := make([]*post.Post, 0)
//cs := make([]*post.Comment, 0)
ps, err = ParseHtmlHackerNews(body, ps)
if err != nil {
return errors.New("ParseHtmlHackerNews: " + err.Error())
}
// Number of updated posts
var updatedPostsCount int64
// Number of new posts
var insertedPostsCount int64
var insertedPostsCommentCount int64
var updatedPostsCommentCount int64
// Number of post parsing errors
var htmlPostErrorCount uint32
// Number of comment parsing errors
var htmlCommentErrorCount uint32
// loop over all parsed posts
for _, htmlpost := range ps {
if htmlpost.WebPostId == "" {
if DebugLevel > 1 {
fmt.Printf("WebPostId not set in %s\n", htmlpost.Title)
}
// Fail early, continue with next post
continue
}
if htmlpost.Err != nil {
if DebugLevel > 1 {
fmt.Println("Single post error in " + geturl + ": " + htmlpost.Err.Error())
}
// Fail early, continue with next post
htmlPostErrorCount++
continue
}
if len(htmlpost.CommentParseErrors) > 0 {
for _, c := range htmlpost.CommentParseErrors {
htmlCommentErrorCount++
if DebugLevel > 2 {
fmt.Println("Single comment error in '" + geturl + "' for WebPostId '" + htmlpost.WebPostId + ": " + c.Err.Error())
}
}
}
// Store post sub
htmlpost.PostSub = sub
tm, err := dbmap.TableFor(reflect.TypeOf(*htmlpost), true)
if err != nil {
return errors.New("Failed to get reflection type: " + err.Error())
}
if DebugLevel > 3 {
fmt.Println("TABLEMAP: " + tm.TableName)
}
// check if post already exists
dbposts := make([]post.Post, 0)
getpostsql := "select * from " + dbmap.Dialect.QuotedTableForQuery("", tm.TableName) + " where WebPostId = :post_id"
_, err = dbmap.Select(&dbposts, getpostsql, map[string]interface{}{
"post_id": htmlpost.WebPostId,
})
if err != nil {
return errors.New(fmt.Sprintf("Getting PostId %s from DB failed: %s", htmlpost.WebPostId, err.Error()))
}
var dbpost *post.Post
if len(dbposts) == 1 {
dbpost = &dbposts[0]
} else if len(dbposts) > 1 {
return errors.New(fmt.Sprintf("Query: %s returned %d rows", getpostsql, len(dbposts)))
}
postcount := len(dbposts)
// New post? then insert
if postcount == 0 {
if DebugLevel > 2 {
fmt.Printf("New post found, inserting htmlpost.WebPostId '%s'\n", htmlpost.WebPostId)
}
// Reset the rowcount info
dbmap.LastOpInfo.Reset()
htmlpost.CommentCount = uint64(len(htmlpost.Comments))
// Insert the new post into the database
err = dbmap.InsertWithChilds(htmlpost)
if DebugLevel > 2 {
// Print out the crawled info
fmt.Println("----------- INSERT POST START -----------------")
fmt.Println(htmlpost.String("INSERT: "))
}
if err != nil {
return errors.New("insert into table " + dbmap.Dialect.QuoteField(tm.TableName) + " failed: " + err.Error())
}
if DebugLevel > 2 {
// Print out the end of the crawled info
fmt.Println("----------- INSERT POST END -------------------")
}
insertedPostsCount += dbmap.LastOpInfo.RowCount
insertedPostsCommentCount += dbmap.LastOpInfo.ChildInsertRowCount
} else {
// Post already exists, get the full post with its comments from the db
res, err := dbmap.GetWithChilds(post.Post{}, 9999999999, 0, dbpost.Id)
if err != nil {
return errors.New("get failed: " + err.Error())
}
if res == nil {
return errors.New(fmt.Sprintf("Get post for id %d did not return any rows ", dbpost.Id))
}
dbpost = res.(*post.Post)
// Check if an update is needed
var updateNeeded bool
updateNeeded, err = AddUpdatableChilds(htmlpost, dbpost, dbmap)
if err != nil {
return errors.New(fmt.Sprintf("CheckIfDataChanged for post '%s' failed: %s", htmlpost.WebPostId, err.Error()))
}
//if htmlpost.Score != dbpost.Score {
if updateNeeded {
// The post changed, do an update into the database
//fmt.Println("Post Date db: " + dbpost.PostDate.String() + ", html: " + htmlpost.PostDate.String())
//fmt.Printf("Post Score db: %d, html: %d\n", dbpost.Score, htmlpost.Score)
if DebugLevel > 2 {
fmt.Println("----------- UPDATE POST START -----------------")
fmt.Println(dbpost.String("UPDATE1: "))
fmt.Printf("From score %d to score %d\n", dbpost.Score, htmlpost.Score)
}
dbpost.Score = htmlpost.Score
dbpost.PostDate = htmlpost.PostDate
// Reset the rowcount info
dbmap.LastOpInfo.Reset()
// Update the posts together with its comments
affectedrows, err := dbmap.UpdateWithChilds(dbpost)
switch {
case err != nil:
return errors.New("update table " + tm.TableName + " failed: " + err.Error())
case affectedrows == 0:
return errors.New(fmt.Sprintf("update table %s for Id %d did not affect any lines", tm.TableName, dbpost.Id))
default:
updatedPostsCount += dbmap.LastOpInfo.RowCount
insertedPostsCommentCount += dbmap.LastOpInfo.ChildInsertRowCount
updatedPostsCommentCount += dbmap.LastOpInfo.ChildUpdateRowCount
dbpost.CommentCount += uint64(dbmap.LastOpInfo.ChildInsertRowCount)
_, err = dbmap.Update(dbpost)
if err != nil {
return errors.New(fmt.Sprintf("Update for post '%s' failed: %s", dbpost.WebPostId, err.Error()))
}
if DebugLevel > 2 {
// Print out the update info
fmt.Println("----------- UPDATE POST COMMIT -----------------")
fmt.Println(dbpost.String("UPDATE2: "))
fmt.Println("----------- UPDATE POST END -------------------")
}
}
}
}
}
if insertedPostsCount == 0 && updatedPostsCount == 0 {
if DebugLevel > 2 {
fmt.Println("No new posts found at " + geturl)
}
return
}
if DebugLevel > 2 {
fmt.Printf("%d new posts have been inserted from %s\n", insertedPostsCount, geturl)
fmt.Printf("%d posts have been updated from %s\n", updatedPostsCount, geturl)
fmt.Printf("%d new comments have been inserted from %s\n", insertedPostsCommentCount, geturl)
fmt.Printf("%d comments have been updated from %s\n", updatedPostsCommentCount, geturl)
fmt.Printf("%d comment errors\n", htmlCommentErrorCount)
}
return
}
