change db from sqlite3 to postgresql

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