Elastic Search,lowercase search doesnt work - elasticsearch

Question

I am trying to search again content using prefix and if I search for diode I get results that differ from Diode. How do I get ES to return result where both diode and Diode return the same results? This is the mappings and settings I am using in ES.
"settings":{
"analysis": {
"analyzer": {
"lowercasespaceanalyzer": {
"type": "custom",
"tokenizer": "whitespace",
"filter": [
"lowercase"
]
}
}
}
},
"mappings": {
"articles": {
"properties": {
"title": {
"type": "text"
},
"url": {
"type": "keyword",
"index": "true"
},
"imageurl": {
"type": "keyword",
"index": "true"
},
"content": {
"type": "text",
"analyzer" : "lowercasespaceanalyzer",
"search_analyzer":"whitespace"
},
"description": {
"type": "text"
},
"relatedcontentwords": {
"type": "text"
},
"cmskeywords": {
"type": "text"
},
"partnumbers": {
"type": "keyword",
"index": "true"
},
"pubdate": {
"type": "date"
}
}
}
}
here is an example of the query I use
POST _search
{
"query": {
"bool" : {
"must" : {
"prefix" : { "content" : "capacitance" }
}
}
}
}

Answer 1

it happens because you use two different analyzers at search time and at indexing time.
So when you input query "Diod" at search time because you use "whitespace" analyzer your query is interpreted as "Diod".
However, because you use "lowercasespaceanalyzer" at index time "Diod" will be indexed as "diod". Just use the same analyzer both at search and index time, or analyzer that lowercases your strings because default "whitespace" analyzer doesn't https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-whitespace-analyzer.html

Answer 2

There will be no term of Diode in your index. So if you want to get same results, you should let your query context analyzed by same analyzer.
You can use Query string query like
"query_string" : {
"default_field" : "content",
"query" : "Diode",
"analyzer" : "lowercasespaceanalyzer"
}
UPDATE
You can analyze your context before query.
AnalyzeResponse resp = client.admin().indices()
.prepareAnalyze(index, text)
.setAnalyzer("lowercasespaceanalyzer")
.get();
String analyzedContext = resp.getTokens().get(0);
...
Then use analyzedContext as new query context.