add backend supporting opengraph and comments
This commit is contained in:
151
backend/datastore/mapper.go
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151
backend/datastore/mapper.go
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@ -0,0 +1,151 @@
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package datastore
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import (
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"database/sql"
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"fmt"
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"git.sa.vin/any-remark/backend/types"
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"math/rand"
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)
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type Mapper interface {
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GetOpenGraphData(url string) (string, error)
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SaveOpenGraphData(url, opengraph string) error
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AddComment(req types.AddCommentRequest) error
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GetComments(url string) ([]types.Comment, error)
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}
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type mapper struct {
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db *sql.DB
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}
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func NewMapper(db *sql.DB) Mapper {
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// Empty function for NewMapper
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return &mapper{
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db: db,
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}
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}
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func (m *mapper) GetOpenGraphData(url string) (string, error) {
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// get the opengraph data from the db table named "webpages" using the url
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query := `SELECT opengraph FROM webpages WHERE url = ?`
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rows, err := m.db.Query(query, url)
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if err != nil {
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if err == sql.ErrNoRows {
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return "", fmt.Errorf("no data found in db for url: %s", url)
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}
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return "", fmt.Errorf("error getting webpage data from db: %s", err)
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}
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defer rows.Close()
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// get the opengraph data from the rows array
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var opengraph string
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for rows.Next() {
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err = rows.Scan(&opengraph)
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if err != nil {
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return "", fmt.Errorf("error scanning opengraph data: %s", err)
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}
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return opengraph, nil
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}
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return "", fmt.Errorf("no data found in db for url: %s", url)
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}
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// SaveOpenGraphData saves the opengraph data to the db
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func (m *mapper) SaveOpenGraphData(url, opengraph string) error {
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// generate a unique id for the webpage make it 24 bytes long
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id := "wp_" + generateID(24)
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// insert the opengraph data to the db table named "webpages" using the url
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query := `INSERT INTO webpages (id, url, opengraph) VALUES (?, ?, ?)`
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_, err := m.db.Exec(query, id, url, opengraph)
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if err != nil {
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return fmt.Errorf("error inserting webpage data to db: %s", err)
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}
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return nil
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}
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func (m *mapper) GetWebpageID(url string) (string, error) {
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// get the id of the webpage from the db table named "webpages" using the url
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query := `SELECT id FROM webpages WHERE url = ?`
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rows, err := m.db.Query(query, url)
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if err != nil {
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if err == sql.ErrNoRows {
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return "", fmt.Errorf("no data found in db for url: %s", url)
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}
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return "", fmt.Errorf("error getting webpage data from db: %s", err)
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}
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defer rows.Close()
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// get the id from the rows array
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var id string
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for rows.Next() {
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err = rows.Scan(&id)
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if err != nil {
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return "", fmt.Errorf("error scanning webpage id: %s", err)
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}
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return id, nil
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}
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return "", fmt.Errorf("no data found in db for url: %s", url)
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}
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func (m *mapper) AddComment(req types.AddCommentRequest) error {
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webpageID, err := m.GetWebpageID(req.URL)
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if err != nil {
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return fmt.Errorf("error getting webpage id: %s", err)
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}
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// generate a unique id for the comment make it 24 bytes long
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id := "c_" + generateID(24)
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// insert the comment data to the db table named "comments" using the url
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query := `INSERT INTO comments (id, content, webpage_id, commenter) VALUES (?, ?, ?, ?)`
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_, err = m.db.Exec(query, id, req.Comment, webpageID, req.UserID)
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if err != nil {
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return fmt.Errorf("error inserting comment data to db: %s", err)
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}
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return nil
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}
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func (m *mapper) GetComments(url string) ([]types.Comment, error) {
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webpageID, err := m.GetWebpageID(url)
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if err != nil {
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return nil, fmt.Errorf("error getting webpage id: %s", err)
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}
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// TODO: add up vote and down vote counts
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// TODO: attach avatar url to commenter
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// TODO: provide order by recent or most upvoted
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// TODO: bubble up the current user's comments
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// get the comments from the db table named "comments" using the webpage_id
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query := `SELECT id, content, commenter FROM comments WHERE webpage_id = ?`
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rows, err := m.db.Query(query, webpageID)
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if err != nil {
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if err == sql.ErrNoRows {
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return nil, fmt.Errorf("no data found in db for url: %s", url)
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}
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return nil, fmt.Errorf("error getting comments from db: %s", err)
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}
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defer rows.Close()
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// get the comments from the rows array
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var comments []types.Comment
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for rows.Next() {
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var comment types.Comment
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err = rows.Scan(&comment.ID, &comment.Content, &comment.Commenter)
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if err != nil {
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return nil, fmt.Errorf("error scanning comments: %s", err)
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}
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comments = append(comments, comment)
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}
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return comments, nil
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}
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func generateID(n int) string {
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// generate a unique id for the webpage make it 24 bytes
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// long using the following character set
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charSet := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
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charSetLen := len(charSet)
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id := make([]byte, n)
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for i := range id {
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// choose a random character from the character set
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id[i] = charSet[rand.Intn(charSetLen)]
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}
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return string(id)
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}
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