change db from sqlite3 to postgresql

internal/model/database/articles.go

@@ -5,13 +5,12 @@ import (
 	"database/sql"
 )
 
-// TODO docstring
 type ArticleModel struct {
-	DB       *sql.DB
-	DbDriver string
+	DB *sql.DB
 }
 
-// TODO docstring
+// Gets all the article objects from the database. This may throw an error if
+// the connection to the database fails.
 func (m *ArticleModel) All() ([]model.Article, error) {
 	stmt := `
         SELECT id, title, sourceUrl, author, content, publishDate, fetchDate 
@@ -41,16 +40,18 @@ func (m *ArticleModel) All() ([]model.Article, error) {
 	return articles, nil
 }
 
-// TODO docstring
+// Will use the full-text search features of the underlying database to search
+// articles for a given search query. This may fail if the connection to the
+// database fails.
 func (m *ArticleModel) Search(query string) ([]model.Article, error) {
 	stmt := `
-        SELECT id, title, sourceUrl, author, content, publishDate, fetchDate
-        FROM articles JOIN ( 
-            SELECT id as id2, rank FROM fts_articles WHERE content MATCH ?
-        ) ON id = id2 
-        ORDER BY rank ASC, publishDate DESC
-        LIMIT 10
-    `
+		SELECT id, title, sourceurl, author, content, publishdate, fetchDate
+		FROM articles
+		WHERE fts_vector @@ to_tsquery('german', $1)
+		ORDER BY ts_rank(fts_vector, to_tsquery('german', $1)) DESC
+		LIMIT 10
+	`
+
 	rows, err := m.DB.Query(stmt, query)
 	if err != nil {
 		return nil, err
@@ -70,7 +71,6 @@ func (m *ArticleModel) Search(query string) ([]model.Article, error) {
 	if err = rows.Err(); err != nil {
 		return nil, err
 	}
-
 	return articles, nil
 }
 
@@ -78,55 +78,20 @@ func (m *ArticleModel) Search(query string) ([]model.Article, error) {
 // article will be ignored. May throw an error if the execution of the database
 // query fails.
 func (m *ArticleModel) Insert(a *model.Article) error {
-	// begin transaction
-	_, err := m.DB.Begin()
-	if err != nil {
-		return err
-	}
-
 	// insert article
 	stmt := `INSERT INTO articles (title, sourceUrl, author, content, publishDate, fetchDate)
-             VALUES (?, ?, ?, ?, ?, ?)
+             VALUES ($1, $2, $3, $4, $5, $6)
     `
-	result, err := m.DB.Exec(stmt, a.Title, a.SourceUrl, a.Author, a.Content, a.PublishDate, a.FetchDate)
-	if err != nil {
-		return err
-	}
-	lastId, err := result.LastInsertId()
-	if err != nil {
-		return err
-	}
-
-	// insert into fts_articles for full-text search
-	stmt = `INSERT INTO fts_articles (id, content)
-             VALUES (?, ? || '\n' || ? || '\n' || ?)
-    `
-	_, err = m.DB.Exec(stmt, lastId, a.Title, a.Author, a.Content)
+	_, err := m.DB.Exec(stmt, a.Title, a.SourceUrl, a.Author, a.Content, a.PublishDate, a.FetchDate)
 	return err
 }
 
 // TODO docstring
 func (m *ArticleModel) Update(a *model.Article) error {
-	// begin transaction
-	_, err := m.DB.Begin()
-	if err != nil {
-		return err
-	}
-
-	// insert article
 	stmt := `UPDATE articles 
-             SET title = ?, sourceUrl = ?, author = ?, content = ?, publishDate = ?, fetchDate = ?
-             WHERE id = ?
+             SET title = $1, sourceUrl = $2, author = $3, content = $4, publishDate = $5, fetchDate = $6
+             WHERE id = $7
     `
-	_, err = m.DB.Exec(stmt, a.Title, a.SourceUrl, a.Author, a.Content, a.PublishDate, a.FetchDate, a.Identifier)
-	if err != nil {
-		return err
-	}
-
-	// insert into fts_articles for full-text search
-	stmt = `INSERT INTO fts_articles (id, content)
-             VALUES (?, ? || '\n' || ? || '\n' || ?)
-    `
-	_, err = m.DB.Exec(stmt, a.Identifier, a.Title, a.Author, a.Content)
+	_, err := m.DB.Exec(stmt, a.Title, a.SourceUrl, a.Author, a.Content, a.PublishDate, a.FetchDate, a.Identifier)
 	return err
 }

internal/model/database/responeses.go

@@ -6,11 +6,11 @@ import (
 )
 
 type ResponseModel struct {
-	DB       *sql.DB
-	DbDriver string
+	DB *sql.DB
 }
 
-// TODO docstring
+// Get all the response object from the database. May throw an error if the
+// connection to the database fails.
 func (m *ResponseModel) All() ([]model.Response, error) {
 	stmt := `
         SELECT url, content, fetchDate, processed
@@ -39,7 +39,8 @@ func (m *ResponseModel) All() ([]model.Response, error) {
 	return responses, nil
 }
 
-// TODO docstring
+// Gets all those Response objects where the processed column is set to false.
+// May throw an error if the connection to the database fails.
 func (m *ResponseModel) UnprocessedUrls() ([]string, error) {
 	stmt := `
         SELECT url 
@@ -69,12 +70,28 @@ func (m *ResponseModel) UnprocessedUrls() ([]string, error) {
 	return urls, nil
 }
 
-// TODO docstring
+// Checks if a given url exits in the database as a response. This may throw an
+// error if the connection to the database fails.
+func (m *ResponseModel) UrlExists(url string) (bool, error) {
+	stmt := `
+		SELECT count(url) > 0 FROM responses WHERE url = $1
+    `
+
+	var result bool
+	row := m.DB.QueryRow(stmt, url)
+	err := row.Scan(&result)
+
+	return result, err
+}
+
+// Gets a certain Response object by the unique url. This may throw an error if
+// there does not exist an response with the given url or the connection to the
+// database fails.
 func (m *ResponseModel) GetByUrl(url string) (model.Response, error) {
 	stmt := `
         SELECT url, content, fetchDate, processed
         FROM responses 
-        WHERE url = ?
+        WHERE url = $1
     `
 
 	res := model.Response{}
@@ -84,19 +101,33 @@ func (m *ResponseModel) GetByUrl(url string) (model.Response, error) {
 	return res, err
 }
 
-// TODO docstring
-func (m *ResponseModel) Insert(url string, content string) error {
+// Inserts a new response object into the database given the url and response
+// body. This may fail on an unique contraint of the url or the connection to
+// the database.
+func (m *ResponseModel) Insert(url string, content []byte) error {
 	// insert response
-	stmt := `INSERT INTO responses (url, content) VALUES (?, ?)`
+	stmt := `INSERT INTO responses (url, content) VALUES ($1, $2)`
 	_, err := m.DB.Exec(stmt, url, content)
 
 	return err
 }
 
-// TODO docstring
+// Updates a response object in the database using the url of the given response
+// object as the id. This may throw an error if connection to the database
+// fails.
+func (m *ResponseModel) Update(res *model.Response) error {
+	// insert response
+	stmt := `UPDATE responses SET content = $1, fetchDate = $2, processed = $3 WHERE url = $4`
+	_, err := m.DB.Exec(stmt, res.Content, res.FetchDate, res.Processed, res.Url)
+
+	return err
+}
+
+// Sets the processed column of a certain response entry in the database, given
+// an url, to true. This may fail if the connection to the database fails.
 func (m *ResponseModel) Processed(url string) error {
 	// insert response
-	stmt := `UPDATE responses SET processed = true WHERE url = ?`
+	stmt := `UPDATE responses SET processed = true WHERE url = $1`
 	_, err := m.DB.Exec(stmt, url)
 
 	return err

internal/model/response.go

@@ -5,7 +5,7 @@ import "time"
 // A simple cache for requests.
 type Response struct {
 	Url       string
-	Content   string
-    Processed bool
+	Content   []byte
+	Processed bool
 	FetchDate time.Time
 }