# utils

This library contains various utility modules to ease development work.

1. counter: Module to generate unique ID.
   1. transactionIdGenerator: returns a function which can be used in a mongoose schema pre save hook to generate a unique universalTransactionId.
   2. transactionIdGeneratorParallel: returns a function which can be used in a mongoose schema pre save hook to generate a unique universalTransactionId. This function should be used when hook is used in parallel middleware.
   3. getIdGenerator: returns a function which can be used in a mongoose schema pre save hook to generate a unique id for each document in a specific collection. It takes two arguments: 1. prefix 2. collectionName
   4. setDefaults: function to set default startValue of Id generated by getIdGenerator. It takes two arguments: 1. collectionName 2. defaultValue
   5. getCount: increments the count of Id and triggers a callback specified in the argument. It takes three arguments 1. collectionName 2. expiry of Id(can be null) 3. callback function
2. cache: Helper functions to use Redis as a cache for user sessions
   1. uuid() : Generates a UUID without “-“
   2. addToken(_token, _default, _uuidOfUI, _expiry) : Add a new user token with the UUID for UI session with expiry
   3. addUISessions(_uuidOfUI, _token, _uiHeartbeatTimeOut): Start tracing a UI session
   4. handleHeartBeat(_uuidOfUI, _token, _uiHeartbeatTimeOut): handle heartbeats from UI
   5. showUISessions(_token): Get the list of active UI sessions
   6. isValidToken(_k): Check if the given key _k is a valid token
   7. isBlacklistedToken(_k): Check if the given key _k is a blacklisted token
   8. blacklist(_token, _expiry): Blacklist a token with the given expiry
   9. refreshToken(_tokenOld, _tokenNew, _expiry): Used when a new token is issued.
3. date: returns a date, months before specified month. Takes one argument: month
4. IDGenerator:
   1. getUniqueID: generates a uniqueID which can be a candidate _id of a model.
5. moveToES: move data to elastic search
   1. init: initialize object. Takes four args crud, mastername, logger, fields.
   2. moveToES: move a document to elastic search server. Takes one arg: doc
   3. moveAll: move all deleted document to elastic search. Takes two args: req, res
6. rand: returns a random integer. Takes one arg: length of integer.
7. logger: returns a log4j object compatible with aou crud library.