Documentation

Module: db-controller

This module enables secure execution of the basic queries. It prevents deleting any entry that some user might be editing at the moment. It also prevents editing the entry if someone else is already editing it. It does so through token exchange system that gives editing rights to whoever obtains it. The token only works for a particular entry in the database. Additionally, the functions for critical queries deleteQuery, updateQuery and requestEditing will never be executed synchronously. This is implemented with an adapted Bakery algorithm.
Version:
  • 1.0
Author:
  • Luka Kralj

Methods

<async, inner> cancelEditing(entryTable, entryID, token)

Call this to delete the current token. This will allow other users to edit this entry. If the token is invalid, an error message will be returned.
Parameters:
Name Type Description
entryTable string Name of the table that we are editing.
entryID string Key of the entry that we are editing
token string Token that is used for verifying the edit permissions.
Returns:
JSON object that contains response data or error message.
Type
Promise.<JSON>

<async, inner> deleteAccessToken(accessToken)

Deletes the access token specified.
Parameters:
Name Type Description
accessToken string Access token we are editing.
Returns:
JSON object that contains response data or error message.
Type
Promise.<JSON>

<async, inner> deleteQuery(sql, entryTable, entryID)

Call this for DELETE queries.
Parameters:
Name Type Description
sql string The SQL query.
entryTable string Name of the table involved in the query.
entryID string Key of the entry that is being deleted.
Returns:
JSON object that contains response data or error message, if the query was unsuccessful.
Type
Promise.<JSON>

<async, inner> editTokensEntryExists(database, entryTable, entryID, token)

Check if the entry with the given parameters exists in the EditTokens table.
Parameters:
Name Type Description
database Database
entryTable string
entryID string
token string
Returns:
True if such entry exists, false if not.
Type
Promise.<boolean>

<inner> getErrResponse(cause)

Generate a JSON error response.
Parameters:
Name Type Description
cause string
Returns:
Error response.
Type
JSON

<async, inner> getResult(sql, database, treatResponse)

Helper function that executes the query.
Parameters:
Name Type Description
sql string Query to execute.
database Database Database object to execute the query on.
treatResponse function Decide how the response of a successful query is modified.
Returns:
Result of the query or error response, if query unsuccessful.
Type
JSON

<inner> getSQLErrorResponse(err)

Formats the error response to give some information about the query error (type, code, error number, SQL message).
Parameters:
Name Type Description
err Error Error thrown by the database query function.
Returns:
Formatted error response.
Type
JSON

<inner> getSuccessfulResponse(response)

Formats a successful response. Enables all responses to follow the same format.
Parameters:
Name Type Description
response JSON Preformatted query-specific response.
Returns:
A formatted response.
Type
JSON

<async, inner> insertQuery(sql)

Call this for INSERT queries.
Parameters:
Name Type Description
sql string The SQL query.
Returns:
JSON object that contains response data or error message, if the query was unsuccessful.
Type
Promise.<JSON>

<async, inner> isValidEntry(database, entryTable, entryID)

Checks if the table name and table ID pair actually represent some valid database entry.
Parameters:
Name Type Description
database Database
entryTable string
entryID string
Returns:
True if entry exists, false if not.
Type
Promise.<boolean>

<async, inner> nonCriticalQuery(sql, type, treatResponse)

A helper function for insertQuery and selectQuery.
Parameters:
Name Type Description
sql string The SQL query.
type string "select" or "insert"
treatResponse function This function is called to format the query response, if the query was successful.
Returns:
JSON object that contains response data or error message, if the query was unsuccessful.
Type
Promise.<JSON>

<async, inner> refreshToken(entryTable, entryID, token)

Call this to refresh the current token. This will generate a new token with a new expiration time. If the token is invalid, an error message will be returned.
Parameters:
Name Type Description
entryTable string Name of the table that we are editing.
entryID string Key of the entry that we are editing
token string Token that is used for verifying the edit permissions.
Returns:
JSON object that contains response data or error message.
Type
Promise.<JSON>

<async, inner> requestEditing(entryTable, entryID)

Request editing for the specific entry.
Parameters:
Name Type Description
entryTable string Table that we want to edit.
entryID string ID of the entry in that table that we want to edit.
Returns:
Response containing the valid token, or error message.
Type
Promise.<JSON>

<async, inner> selectQuery(sql)

Call this for SELECT queries.
Parameters:
Name Type Description
sql string The SQL query.
Returns:
JSON object that contains response data or error message, if the query was unsuccessful.
Type
Promise.<JSON>

<inner> sleep(ms)

Await for this function to pause execution for a certain time.
Parameters:
Name Type Description
ms number Time in milliseconds
Returns:
Type
Promise

<inner> startsWith(toCheck, compareTo)

Shorthand function for comparing the start of a string. Leading spaces and capitalisation are ignored.
Parameters:
Name Type Description
toCheck string A string the start of which we want to check.
compareTo string A string that should appear at the start of the toCheck.
Returns:
True if toCheck starts with compareTo, false otherwise.
Type
boolean

<async, inner> updateAccessToken(accessToken, newExpiration)

Updates the expiration of an access token specified.
Parameters:
Name Type Description
accessToken string Access token we are editing.
newExpiration Date New expiration for this token.
Returns:
JSON object that contains response data or error message.
Type
Promise.<JSON>

<async, inner> updateQuery(sql, entryTable, entryID, token)

Call this for UPDATE queries.
Parameters:
Name Type Description
sql string The SQL query.
entryTable string Name of the table involved in the query.
entryID string Key of the entry that is being updated.
token string Token that is used for verifying the edit permissions.
Returns:
JSON object that contains response data or error message, if the query was unsuccessful.
Type
Promise.<JSON>