I answered your same question on Stack Overflow, but will include here for completeness.
The issue is that the casing of properties within the fields in the index mappings, and the casing of properties that NEST will send by default are different, so the nested must clauses within the should clause of the bool query that is generated by NEST will never be matched by any documents because of the field casing difference.
NEST by default camel cases property names, but the fields in the index mappings and documents in your example are all pascal cased, so the field names generated by NEST will not match those within the mapping. You can easily change NEST's field casing behaviour by using the DefaultFieldNameInferrer(Func<string, string>) method on ConnectionSettings. A delegate that simply returns the string value passed will leave field names as they are on the POCOs.
Here's a complete working example
private static void Main()
{
const string componentIndex = "componenttypeindex";
const string projectIndex = "projecttypeindex";
var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
var settings = new ConnectionSettings(pool)
.DefaultIndex(componentIndex)
.DefaultMappingFor<ComponentTypES>(i => i.IndexName(componentIndex).TypeName("Componenttype").IdProperty(f => f.ComponentID))
.DefaultMappingFor<ProjectTypES>(j => j.IndexName(projectIndex).TypeName("Projecttype").IdProperty(f => f.ProjectID))
.DefaultFieldNameInferrer(f => f)
.DefaultTypeName("_doc")
.DisableDirectStreaming()
.PrettyJson()
.OnRequestCompleted(callDetails =>
{
if (callDetails.RequestBodyInBytes != null)
{
Console.WriteLine(
$"{callDetails.HttpMethod} {callDetails.Uri} \n" +
$"{Encoding.UTF8.GetString(callDetails.RequestBodyInBytes)}");
}
else
{
Console.WriteLine($"{callDetails.HttpMethod} {callDetails.Uri}");
}
Console.WriteLine();
if (callDetails.ResponseBodyInBytes != null)
{
Console.WriteLine($"Status: {callDetails.HttpStatusCode}\n" +
$"{Encoding.UTF8.GetString(callDetails.ResponseBodyInBytes)}\n" +
$"{new string('-', 30)}\n");
}
else
{
Console.WriteLine($"Status: {callDetails.HttpStatusCode}\n" +
$"{new string('-', 30)}\n");
}
});
var client = new ElasticClient(settings);
foreach (var index in new[] { componentIndex, projectIndex })
{
if (client.IndexExists(index).Exists)
client.DeleteIndex(index);
client.CreateIndex(index, c => c
.Mappings(m =>
{
if (index == projectIndex)
return m.Map<ProjectTypES>(mm => mm.AutoMap());
else
return m.Map<ComponentTypES>(mm => mm.AutoMap());
})
);
}
client.Bulk(b => b
.IndexMany(new[] {
new ComponentTypES
{
ComponentID = "5342e739-1635-4021-baf2-55e25b95b8ec",
Componentname = "TestComponent1",
Summary = "this is summary of test component1"
},
new ComponentTypES
{
ComponentID = "90781386-8065-11e9-bc42-526af7764f64",
Componentname = "TestComponent2",
Summary = "this is summary of test component3"
},
new ComponentTypES
{
ComponentID = "19871386-8065-11e9-bc42-526af7764f64",
Componentname = "some xyz component test",
Summary = "this is summary test of test xyz"
},
})
.IndexMany(new[] {
new ProjectTypES
{
ProjectID = "5342e739-2019-4021-baf2-55e25b95b8ec",
Projectname = "Test Project1",
Summary = "summary of Test Project1",
Description = "Description of TestProject1"
},
new ProjectTypES
{
ProjectID = "5342f739-2019-4021-baf2-55e25b95b8ba",
Projectname = "Test Project2",
Summary = "summary of Test Project2",
Description = "Description of TestProject1"
},
new ProjectTypES
{
ProjectID = "6342f739-2020-4021-baf2-55e25b95b8ac",
Projectname = "some PQRS project",
Summary = "summary of PQRS Project",
Description = "Description of PQORS Project1"
},
})
.Refresh(Refresh.WaitFor)
);
var query = "test";
var response = client.Search<object>(s => s
.Index(Indices.Index(typeof(ComponentTypES)).And(typeof(ProjectTypES)))
.Type(Types.Type(typeof(ComponentTypES), typeof(ProjectTypES)))
.Query(q =>
(q
.MultiMatch(m => m
.Fields(f => f
.Field(Infer.Field<ComponentTypES>(ff => ff.Componentname))
.Field(Infer.Field<ComponentTypES>(ff => ff.Summary, 1.1))
)
.Operator(Operator.Or)
.Query(query)
) && +q
.Term("_index", componentIndex)
) ||
(q
.MultiMatch(m => m
.Fields(f => f
.Field(Infer.Field<ProjectTypES>(ff => ff.Projectname))
.Field(Infer.Field<ProjectTypES>(ff => ff.Summary, 0.3))
)
.Operator(Operator.Or)
.Query(query)
) && +q
.Term("_index", projectIndex)
)
)
);
}
public class ComponentTypES
{
public string ComponentID { get; set; }
public string Componentname { get; set; }
public string Summary { get; set; }
}
public class ProjectTypES
{
public string ProjectID { get; set; }
public string Projectname { get; set; }
public string Summary { get; set; }
public string Description { get; set; }
}
The resulting JSON query for the search is
POST http://localhost:9200/componenttypeindex%2Cprojecttypeindex/Componenttype%2CProjecttype/_search?pretty=true&typed_keys=true
{
"query": {
"bool": {
"should": [
{
"bool": {
"filter": [
{
"term": {
"_index": {
"value": "componenttypeindex"
}
}
}
],
"must": [
{
"multi_match": {
"fields": [
"Componentname",
"Summary^1.1"
],
"operator": "or",
"query": "test"
}
}
]
}
},
{
"bool": {
"filter": [
{
"term": {
"_index": {
"value": "projecttypeindex"
}
}
}
],
"must": [
{
"multi_match": {
"fields": [
"Projectname",
"Summary^0.3"
],
"operator": "or",
"query": "test"
}
}
]
}
}
]
}
}
}
which returns 5 results