carlosmpv / persistent

A simples golang library for persisting structs into key/value based databses

Persistent

A simple tool for storing structs in key value based storages.

It does not provide the database.

How to use it

1. Add it to your project

   go get github.com/carlosmpv/persistent

2. Then, implement the Storager interface.

   type exampleStorager struct {
       db map[string][]byte
   }
   
   // stores a value (v) with a key (k)
   func (ts *exampleStorager) Save(k, v []byte) error {
       ts.db[string(k)] = v
       return nil
   }
   
   // gets the value given a key (k)
   func (ts *exampleStorager) Load(k []byte) ([]byte, error) {
       val, ok := ts.db[string(k)]
       if !ok {
           return nil, errors.New("value is not stored")
       }
   
       return val, nil
   }

   This is a very simple storager that uses a map[string][]byte as database. It could be a redis set and get instead on each method.

Persistent variables

Persistent variables are wrappers around golang's standard variable types that uses a given storager to save and load its values.

Declaring a persistent variable

str := NewPersistentString("Hello world!")
empty := EmptyPersistentString()

Those are pointers, so to get its value:

... := *str

Persisting a value

err := str.Persist(storager, "key")
if err != nil {
    ...
}

Restoring a value

err := nStr.Restore(storager, "key")
// *nStr == *str

Structs that contains persistent fields can also be persisted and restored using PersistStruct and RestoreStruct

Check persistent_test.go and its test cases to better understand how to use it