elasticsearch: search for parts of words - php

Question

I'm trying to learn how to use elasticsearch (using elasticsearch-php for queries). I have inserted a few data, which look something like this:
['id' => 1, 'name' => 'butter', 'category' => 'food'],
['id' => 2,'name' => 'buttercup', 'category' => 'food'],
['id' => 3,'name' => 'something else', 'category' => 'butter']
Now I created a search query which looks like this:
$query = [
'filtered' => [
'query' => [
'bool' => [
'should' => [
['match' => [
'name' => [
'query' => $val,
'boost' => 7
]
]],
['match' => [
'category' => [
'query' => $val,
'boost' => 5
]
]],
],
]
]
]
];
where $val is the search term. This works nicely, the only problem I have: when I search for "butter", I find ids 1 and 3, but not 2, because the searchterm seems to match exact words only. Is there a way to search "within words", or, in mysql terms, to do something like WHERE name LIKE '%val%' ?

Answer 1

You can try the wildcard query
$query = [
'filtered' => [
'query' => [
'bool' => [
'should' => [
['wildcard' => [
'name' => [
'query' => '*'.$val.'*',
'boost' => 7
]
]],
['wildcard' => [
'category' => [
'query' => '*'.$val.'*',
'boost' => 5
]
]],
],
]
]
]
];
or the query_string query.
$query = [
'filtered' => [
'query' => [
'bool' => [
'should' => [
['query_string' => [
'default_field' => 'name',
'query' => '*'.$val.'*',
'boost' => 7
]],
['query_string' => [
'default_field' => 'category',
'query' => '*'.$val.'*',
'boost' => 7
]],
],
]
]
]
];
Both will work but are not really performant if you have lots of data.
The correct way of doing this is to use a custom analyzer with a standard tokenizer and an ngram token filter in order to slice and dice each of your tokens into small ones.