Creating an index Nest - elasticsearch

Question

How would I recreate the following index using Elasticsearch Nest API?
Here is the json for the index including the mapping:
{
"settings": {
"analysis": {
"filter": {
"trigrams_filter": {
"type": "ngram",
"min_gram": 3,
"max_gram": 3
}
},
"analyzer": {
"trigrams": {
"type": "custom",
"tokenizer": "standard",
"filter": [
"lowercase",
"trigrams_filter"
]
}
}
}
},
"mappings": {
"data": {
"_all" : {"enabled" : true},
"properties": {
"text": {
"type": "string",
"analyzer": "trigrams"
}
}
}
}
}
Here is my attempt:
var newIndex = client.CreateIndexAsync(indexName, index => index
.NumberOfReplicas(replicas)
.NumberOfShards(shards)
.Settings(settings => settings
.Add("merge.policy.merge_factor", "10")
.Add("search.slowlog.threshold.fetch.warn", "1s")
.Add("mapping.allow_type_wrapper", true))
.AddMapping<Object>(mapping => mapping
.IndexAnalyzer("trigram")
.Type("string"))
);
The documentation does not mention anything about this?
UPDATE:
Found this post that uses
var index = new IndexSettings()
and then adds Analysis with the string literal json.
index.Add("analysis", #"{json});
Where can one find more examples like this one and does this work?

Answer 1

Creating an index in older versions
There are two main ways that you can accomplish this as outlined in the Nest Create Index Documentation:
Here is the way where you directly declare the index settings as Fluent Dictionary entries. Just like you are doing in your example above. I tested this locally and it produces the index settings that match your JSON above.
var response = client.CreateIndex(indexName, s => s
.NumberOfReplicas(replicas)
.NumberOfShards(shards)
.Settings(settings => settings
.Add("merge.policy.merge_factor", "10")
.Add("search.slowlog.threshold.fetch.warn", "1s")
.Add("mapping.allow_type_wrapper", true)
.Add("analysis.filter.trigrams_filter.type", "nGram")
.Add("analysis.filter.trigrams_filter.min_gram", "3")
.Add("analysis.filter.trigrams_filter.max_gram", "3")
.Add("analysis.analyzer.trigrams.type", "custom")
.Add("analysis.analyzer.trigrams.tokenizer", "standard")
.Add("analysis.analyzer.trigrams.filter.0", "lowercase")
.Add("analysis.analyzer.trigrams.filter.1", "trigrams_filter")
)
.AddMapping<Object>(mapping => mapping
.Type("data")
.AllField(af => af.Enabled())
.Properties(prop => prop
.String(sprop => sprop
.Name("text")
.IndexAnalyzer("trigrams")
)
)
)
);
Please note that NEST also includes the ability to create index settings using strongly typed classes as well. I will post an example of that later, if I have time to work through it.
Creating index with NEST 7.x
Please also note that in NEST 7.x CreateIndex method is removed. Use Indices.Create isntead. Here's the example.
_client.Indices
.Create(indexName, s => s
.Settings(se => se
.NumberOfReplicas(replicas)
.NumberOfShards(shards)
.Setting("merge.policy.merge_factor", "10")));

Answer 2

In case people have NEST 2.0, the .NumberOfReplicas(x).NumberOfShards(y) are in the Settings area now so specify within the lamba expression under Settings.
EsClient.CreateIndex("indexname", c => c
.Settings(s => s
.NumberOfReplicas(replicasNr)
.NumberOfShards(shardsNr)
)
NEST 2.0 has a lot of changes and moved things around a bit so these answers are a great starting point for sure. You may need to adjust a little for the NEST 2.0 update.

Answer 3

Small example :
EsClient.CreateIndex("indexname", c => c
.NumberOfReplicas(replicasNr)
.NumberOfShards(shardsNr)
.Settings(s => s
.Add("merge.policy.merge_factor", "10")
.Add("search.slowlog.threshold.fetch.warn", "15s")
)
#region Analysis
.Analysis(descriptor => descriptor
.Analyzers(bases => bases
.Add("folded_word", new CustomAnalyzer()
{
Filter = new List<string> { "icu_folding", "trim" },
Tokenizer = "standard"
}
)
.TokenFilters(i => i
.Add("engram", new EdgeNGramTokenFilter
{
MinGram = 1,
MaxGram = 20
}
)
)
.CharFilters(cf => cf
.Add("drop_chars", new PatternReplaceCharFilter
{
Pattern = #"[^0-9]",
Replacement = ""
}
)
#endregion
#region Mapping Categories
.AddMapping<Categories>(m => m
.Properties(props => props
.MultiField(mf => mf
.Name(n => n.Label_en)
.Fields(fs => fs
.String(s => s.Name(t => t.Label_en).Analyzer("folded_word"))
)
)
)
#endregion
);

Answer 4

In case anyone has migrated to NEST 2.4 and has the same question - you would need to define your custom filters and analyzers in the index settings like this:
elasticClient.CreateIndex(_indexName, i => i
.Settings(s => s
.Analysis(a => a
.TokenFilters(tf => tf
.EdgeNGram("edge_ngrams", e => e
.MinGram(1)
.MaxGram(50)
.Side(EdgeNGramSide.Front)))
.Analyzers(analyzer => analyzer
.Custom("partial_text", ca => ca
.Filters(new string[] { "lowercase", "edge_ngrams" })
.Tokenizer("standard"))
.Custom("full_text", ca => ca
.Filters(new string[] { "standard", "lowercase" } )
.Tokenizer("standard"))))));

Answer 5

For 7.X plus you can use the following code to create an index with Shards, Replicas and with Automapping:
if (!_elasticClient.Indices.Exists(_elasticClientIndexName).Exists)
{
var response = _elasticClient.Indices
.Create(_elasticClientIndexName, s => s
.Settings(se => se
.NumberOfReplicas(1)
.NumberOfShards(shards)
).Map<YourDTO>(
x => x.AutoMap().DateDetection(false)
));
if (!response.IsValid)
{
// Elasticsearch index status is invalid, log an exception
}
}