How to search a string in the elasticsearch document(indexed) in golang? - search

Question

I am writing a function in golang to search for a string in elasticsearch documents which are indexed. I am using elasticsearch golang client elastic. For example consider the object is tweet,
type Tweet struct {
User string
Message string
Retweets int
}
And the search function is
func SearchProject() error{
// Search with a term query
termQuery := elastic.NewTermQuery("user", "olivere")
searchResult, err := client.Search().
Index("twitter"). // search in index "twitter"
Query(&termQuery). // specify the query
Sort("user", true). // sort by "user" field, ascending
From(0).Size(10). // take documents 0-9
Pretty(true). // pretty print request and response JSON
Do() // execute
if err != nil {
// Handle error
panic(err)
return err
}
// searchResult is of type SearchResult and returns hits, suggestions,
// and all kinds of other information from Elasticsearch.
fmt.Printf("Query took %d milliseconds\n", searchResult.TookInMillis)
// Each is a convenience function that iterates over hits in a search result.
// It makes sure you don't need to check for nil values in the response.
// However, it ignores errors in serialization. If you want full control
// over iterating the hits, see below.
var ttyp Tweet
for _, item := range searchResult.Each(reflect.TypeOf(ttyp)) {
t := item.(Tweet)
fmt.Printf("Tweet by %s: %s\n", t.User, t.Message)
}
// TotalHits is another convenience function that works even when something goes wrong.
fmt.Printf("Found a total of %d tweets\n", searchResult.TotalHits())
// Here's how you iterate through results with full control over each step.
if searchResult.Hits != nil {
fmt.Printf("Found a total of %d tweets\n", searchResult.Hits.TotalHits)
// Iterate through results
for _, hit := range searchResult.Hits.Hits {
// hit.Index contains the name of the index
// Deserialize hit.Source into a Tweet (could also be just a map[string]interface{}).
var t Tweet
err := json.Unmarshal(*hit.Source, &t)
if err != nil {
// Deserialization failed
}
// Work with tweet
fmt.Printf("Tweet by %s: %s\n", t.User, t.Message)
}
} else {
// No hits
fmt.Print("Found no tweets\n")
}
return nil
}
This search is printing tweets by the user 'olivere'. But if I give 'olive' then search is not working. How do I search for a string which is part of User/Message/Retweets?
And the Indexing function looks like this,
func IndexProject(p *objects.ElasticProject) error {
// Index a tweet (using JSON serialization)
tweet1 := `{"user" : "olivere", "message" : "It's a Raggy Waltz"}`
put1, err := client.Index().
Index("twitter").
Type("tweet").
Id("1").
BodyJson(tweet1).
Do()
if err != nil {
// Handle error
panic(err)
return err
}
fmt.Printf("Indexed tweet %s to index %s, type %s\n", put1.Id, put1.Index, put1.Type)
return nil
}
Output:
Indexed tweet 1 to index twitter, type tweet
Got document 1 in version 1 from index twitter, type tweet
Query took 4 milliseconds
Tweet by olivere: It's a Raggy Waltz
Found a total of 1 tweets
Found a total of 1 tweets
Tweet by olivere: It's a Raggy Waltz
Version
Go 1.4.2
Elasticsearch-1.4.4
Elasticsearch Go Library
github.com/olivere/elastic
Could anyone help me on this.? Thank you

Answer 1

How you search and find data depends on your analyser - from your code it's likely that the standard analyser is being used (i.e. you haven't specified an alternative in your mapping).
The Standard Analyser will only index complete words. So to match "olive" against "olivere" you could either:
Change the search process
e.g. switch from a term query to a Prefix query or use a Query String query with a wildcard.
Change the index process
If you want to find strings within larger strings then look at using nGrams or Edge nGrams in your analyser.

Answer 2

multiQuery := elastic.NewMultiMatchQuery(
term,
"name", "address", "location", "email", "phone_number", "place", "postcode",
).Type("phrase_prefix")