IndexDB Notes / sample code

gistfile1.coffee

indexdb notes

dbName = 'someName'

# obtain non-vendored versions of these


# Vars used to open / work with our db instance
window.db = null
request = indexedDB.open(dbName)
# request = indexedDB.open('testdb', versionNum)

# These should typically be handled and implemented per request since everything in indexeddb is async
# request.onerror = (e) -> # do event stuff
# request.onsuccess = (e) -> # do event stuff
#
# A common error is VER_ERR which means DB on disk is later than the verison specified in open
request.onerror = (evt) -> console.error 'dberror: #{evt.target.errorCode}'
request.onsuccess = (evt) -> 
  db = request.result

  # Error events bubble up, so if we set this on our db object, we will have this fire if we have a 
  # request error -> transaction error -> db error
  db.onerror = (e) -> console.error 'dberror: #{evt.target.errorCode}'

# Occurs when a newer version of the db schema is required (new indices / object stores / etc) 
# this is specific to the open db request
request.onupgradeneeded = (evt) ->
  # Creating an object store (entity)
  objectStore = db.createObjectStore('users', { keyPath: 'id' })

  # Creating an index (used for searching)
  # indexName, keyPath, options IDBIndexParameters
  objectStore.createIndex('name', 'name', { unique: false })
  objectStore.createIndex('email', 'email', { unique: true })

  # Seeding data into the store
  # for person in peopleData
    # objectStore.add(person)

# Transaction example
window.addUser = (user) ->

  # Name of the object store, type of transaction
  # <[objectStoreName]>, [<readonly|readwrite|versionchange>], 
  transaction = db.transaction(['users'], 'readwrite')

  # Possible callbacks
  # transaction.onerror = (e) -> this will also bubble up to db.onerror, use preventDefault() to stop propagation/rolling back transaction
  # transaction.oncomplete = (e) -> 
  # transaction.onabort = (e) -> fired when transaction is rolled back

  # To add data, select the object store from the transaction
  objectStore = transaction.objectStore('users')

  # Add the data
  request = objectStore.add(user)

  # Update the data
  # request = objectStore.put(user)

  # Remove the data
  # request = objectStore.delete(<keyValue>)

  # Register callbacks
  # request.onsuccess = (e) -> do somethin!

# Getting a user - chained example
# db.transaction('users').objectStore('users').get(1).onsuccess = (e) -> console.log e.toString()

# Getting many users 
# objectStore = db.transaction('customers').objectStore('customers')

# Simple example - findAll
# objectStore.openCursor().onsuccess = (e) ->
#   # Get our cursor
#   cursor = e.target.result

#   if cursor
#     console.log "Current record is: #{cursor}"

#     # move to the next record
#     cursor.continue()

#   else
#     console.log 'no more entries'

###
# Searching by index examples
###

# Obtain first object for a search
# index = objectStore.index('name')
# index.get('Donna').onsuccess = (e) -> console.log "This is the first donna we have: #{e.target.result}"

# Obtain all matches objects for a search
# index.openCursor().onsuccess = (e) ->
  # Get cursor
  # cursor = e.target.result

  # if cursor
    # console.log "key is: #{cursor.key}  whole object is: #{cursor.value}"
    # cursor.continue()

# Only obtain the keys for a search
# index.openKeyCursor().onsuccess = (e) ->
  # Get cursor
  # cursor = e.target.result

  # if cursor
    # console.log "key is: #{cursor.key}  search value is: #{cursor.value}"
    # cursor.continue()

for the record, this code doesn't actually work or do anything (scoping issues,etc..) but is a reference for how to do some things.