Partial matching GAE search API

Though LIKE statement (partial match) is not supported in Full Text Search, but you could hack around it.

First, tokenize the data string for all possible substrings (hello = h, he, hel, lo, etc.)

def tokenize_autocomplete(phrase):
    a = []
    for word in phrase.split():
        j = 1
        while True:
            for i in range(len(word) - j + 1):
                a.append(word[i:i + j])
            if j == len(word):
                break
            j += 1
    return a

Build an index + document (Search API) using the tokenized strings

index = search.Index(name='item_autocomplete')
for item in items:  # item = ndb.model
    name = ','.join(tokenize_autocomplete(item.name))
    document = search.Document(
        doc_id=item.key.urlsafe(),
        fields=[search.TextField(name='name', value=name)])
    index.put(document)

Perform search, and walah!

results = search.Index(name="item_autocomplete").search("name:elo")

https://code.luasoftware.com/tutorials/google-app-engine/partial-search-on-gae-with-search-api/

just like @Desmond Lua answer, but with different tokenize function:

def tokenize(word):
  token=[]
  words = word.split(' ')
  for word in words:
    for i in range(len(word)):
      if i==0: continue
      w = word[i]
      if i==1: 
        token+=[word[0]+w]
        continue

      token+=[token[-1:][0]+w]

  return ",".join(token)

it will parse hello world as he,hel,hell,hello,wo,wor,worl,world.

it's good for light autocomplete purpose