c# Nest 和 Elasticsearch 聚合

Question

有谁知道如何使用嵌套进行多次聚合？不幸的是，我发现了很多示例，但它们都不起作用。

这是我所拥有的：

Vehicles fields = new Vehicles();

//create a terms query
var query = new TermsQuery
{
    IsVerbatim = true,
    Field = "VehicleOwnerId",
    Terms = new string[] { 25 },
};

var aggregations = new Dictionary<string, IAggregationContainer>
{
    { "years", new AggregationContainer
        {
            Terms = new TermsAggregation(nameof(fields.Year))
            {
                Field = new Field(nameof(fields.Year))
            }
        }
    }
    //,
    //{ "makes", new AggregationContainer
    //    {
    //        Terms = new TermsAggregation("Make")
    //        {
    //            Field = new Field(nameof(fields.Make))
    //        }
    //    }
    //}
};

//create the search request
var searchRequest = new SearchRequest
{
    Query = query,
    From = 0,
    Size = 100,
    Aggregations = aggregations
};

var result = client.SearchAsync<InventoryLiveView>(searchRequest).Result;

var years = result.Aggregations.Terms("years");
Dictionary<string, long> yearCounts = new Dictionary<string, long>();
foreach (var item in years.Buckets)
{
    yearCounts.Add(item.Key, item.DocCount ?? 0);
}

如果我只是像这样执行代码，它就可以工作。年按预期返回聚合。如果我尝试添加另一个字段（如上面注释的那个），它会失败并且我得到零记录。如何在一个查询中获得多个聚合？我到处都看到了它的例子，但我尝试过的例子似乎都没有工作，而且大多数似乎已经过时了（包括 Nest 文档中的一些）。我也尝试过这种与文档非常接近的方法。

//create the search request
var searchRequest = new SearchRequest
{
    Query = query,
    From = 0,
    Size = 100,
    //Aggregations = aggregations
    Aggregations = new AggregationDictionary
    {
        { 
            "childAgg", new ChildrenAggregation("childAgg", typeof(Vehicles ))
            {
                Aggregations = new AggregationDictionary
                {
                    {"years", new TermsAggregation(nameof(fields.VehicleYear))},
                    {"makes", new TermsAggregation(nameof(fields.VehicleMakeName))},
                    {"models", new TermsAggregation(nameof(fields.VehicleModelName))},
                }
            }
        }
    }
};

var result = client.SearchAsync<Vehicles>(searchRequest).Result;

这只会产生一个空引用异常。

Answer 1

我想我永远不会太担心成为一名程序员的骄傲:) 当问题的解决方案暴露出来时，它常常让我感到很愚蠢。

所以我的问题是我试图在聚合中使用的字段是文本并且无法使用。我将所有内容都切换到 ID 字段，多个聚合按预期工作。

所以这个版本的代码就像一个冠军：

Vehicle fields = new Vehicle ();

//create a terms query
var query = new TermsQuery
{
    IsVerbatim = true,
    Field = "VehicleOwnerId",
    Terms = new string[] { "30" },
};

string[] Fields = new[]
{
    nameof(fields.Year),
    nameof(fields.MakeId),
    nameof(fields.ModelId)
};

var aggregations = new Dictionary<string, IAggregationContainer>();
foreach (string sField in Fields)
{
    var termsAggregation = new TermsAggregation(sField)
    {
        Field = sField
    };

    aggregations.Add(sField, new AggregationContainer { Terms = termsAggregation });
}

//create the search request
var searchRequest = new SearchRequest
{
    Query = query,
    From = 0,
    Size = 10,
    Aggregations = aggregations
};

var result = client.SearchAsync<InventoryLiveView>(searchRequest).Result;

var years = result.Aggregations.Terms(nameof(fields.Year));
Dictionary<string, long> yearCounts = new Dictionary<string, long>();
foreach (var item in years.Buckets)
{
    yearCounts.Add(item.Key, item.DocCount ?? 0);
}

我使用邮递员看到的来自 elasticsearch 的确切错误是：

Fielddata is disabled on text fields by default. Set fielddata=true on [MakeName] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead.