bidirectional match on elasticsearch - elasticsearch

Question

I've indexed a list of terms and now I want to query for some of them
Say that I've indexed 'dog food','red dog','dog','food','cats'
How do I create an exact bidirectional match query. ie: I want when search for 'dog' to get only the term dog and not the other terms (because they don't match back).
One primitive solution I thought of is indexing the terms with their length (Words-wise) and then when searching query with lengh X restrict it to the terms of length X. but it seems over complicated.

Answer 1

Create a custom analyzer to lowercase and normalize your search terms. So that would be your index:
{
"settings" : {
"analysis" : {
"analyzer" : {
"my_analyzer_keyword" : {
"type" : "custom",
"tokenizer" : "keyword",
"filter" : [
"asciifolding",
"lowercase"
]
}
}
}
},
"mappings" : {
"your_type" : {
"properties" : {
"name" : {
"type" : "string",
"analyzer" : "my_analyzer_keyword"
}
}
}
}
}
So if you have indexed 'dog' and users types in Dog or dog or DOG, it will match only dog, 'dog food' won't be brought back.

Answer 2

Just set your field's index property to not_analyzed and your query should use term filter to search for text.
As per Evaldas' suggestion, find below a more complete solution, that also keeps the original value indexed with standard analyzer but uses a sub-field with a lowercased version of the terms:
PUT /test
{
"settings": {
"analysis": {
"analyzer": {
"my_keyword_lowercase_analyzer": {
"type": "custom",
"filter": [
"lowercase"
],
"tokenizer": "keyword"
}
}
}
},
"mappings": {
"asset": {
"properties": {
"name": {
"type": "string",
"fields": {
"case_ignore": {
"type": "string",
"analyzer": "my_keyword_lowercase_analyzer"
}
}
}
}
}
}
}
POST /test/asset/1
{
"name":"dog"
}
POST /test/asset/2
{
"name":"dog food"
}
POST /test/asset/3
{
"name":"red dog"
}
GET /test/asset/_search
{
"query": {
"match": {
"name.case_ignore": "Dog"
}
}
}