Elasticsearch does not find characters other than alpha numeric - elasticsearch

Question

I am facing a problem of searching some characters others than alphanumeric.
I tried with many analyzers, but think that for my problem the 'whitespace' analyzer fits perfectly.
I've created an index custom_doc and posted a doc
{
"body": "some text with ### hash signs # inside",
}
but I am not able to find this doc by passing hash inside query string
{
"query": {
"bool": {
"must": [
{
"query_string": {
"fields": [
"body"
],
"query": "#",
"analyzer": "whitespace"
}
}
]
}
}
}
However analyze shows it is tokenized correctly
request
{
"analyzer": "whitespace",
"text": "#"
}
result
{
"tokens": [
{
"token": "#",
"start_offset": 0,
"end_offset": 1,
"type": "word",
"position": 0
}
]
}
There is no custom analyzers, no mappings, no additional filters.
How can I solve the problem? I've checked many similar questions and no improvement. Some people advice to make the field as "not_analyzed" but I still want to have a possibility to use wildcards inside query string, thus changing the field type from "text" to "keyword" is not suitable to me as well. E.g. want this query "so*" to return the posted document.

Answer 1

The problem is that you also need to specify the whitespace analyzer at indexing time. Using it only at search time is not sufficient, because your body of text will have been analyzed by the standard analyzer which has removed the # signs, and thus, you cannot search for them afterwards.
First delete your index and recreate it with the following mapping:
DELETE index
PUT index
{
"mappings": {
"doc": {
"properties": {
"body": {
"type": "text",
"analyzer": "whitespace",
"search_analyzer": "whitespace"
}
}
}
}
}
Then index your document:
PUT index/doc/1
{ "body": "some text with ### hash signs # inside"}
Finally, you can search for the # sign (note that you don't need to specify the whitespace analyzer):
POST index/_search
{
"query": {
"bool": {
"must": [
{
"query_string": {
"fields": [
"body"
],
"query": "#"
}
}
]
}
}
}