c# - 将null设置为文档属性，并在更新时从数据库中删除字段

Question

我有下面的C#类。

public class ElasticSearchDocument
{
    public string Id { get; set; } = Guid.NewGuid().ToString();

    public string Description { get; set; }
}

我还在文档中使用模板，下面的模板用于演示测试。

{
  "version": 2,
  "index_patterns": "documents-test*",
  "order": 2,
  "aliases": {
    "docs-test": {}
  },
  "settings": {
    "number_of_shards": 1
  },
  "mappings": {
    "_doc": {
      "dynamic": "strict",
      "properties": {
        "id": {
          "type": "keyword"
        },
        "description": {
          "enabled": false
        }
      }
    }
  }
}

我将 Description属性设置为 has value并对其进行索引。下面是数据库中的一个示例。

{
  "_index": "documents-test-2019-07-2-2",
  "_type": "_doc",
  "_id": "55096ff7-5072-4ded-b6a3-94b8e155c9d0",
  "_score": 1,
  "_source": {
    "id": "55096ff7-5072-4ded-b6a3-94b8e155c9d0",
    "description": "has value"
  }
}

查询文档，将 Description属性设置为 null，并使用下面的NEST IElasticClient.UpdateAsync方法更新文档。

public async Task<Result> UpdateAsync(
 T document,
 string indexName = null,
 string typeName = null,
 Refresh ? refresh = null,
 CancellationToken cancellationToken =
 default) {

 var response = await Client.UpdateAsync<T,
  object>(
   document.Id,
   u => u.Doc(document)
   .Index(indexName ? ? DocumentMappings.IndexStrategy)
   .Type(typeName ? ? DocumentMappings.TypeName)
   .Refresh(refresh),
   cancellationToken);

 var errorMessage = response.LogResponseIfError(_logger);

 return errorMessage.IsNullOrEmpty() ? Result.Ok() : Result.Fail(errorMessage);
}

问题在于更新命令后，文档的 description字段保持不变，值为 has value。

我认为，最合适的解决方案是将C#类 Description属性设置为null并更新Elastic Search以将其从文档中删除时，以某种方式。

我已经看到了几个答案，但不知道可能有什么更改，或者是否有比 update_by_query更好的解决方案，或者是仅使用NEST忽略 property attribute忽略null的行为(麻烦)

Answer 1

我最终创建了以下方法。

public async Task<Result> UpdateAsync(
    T document, 
    string indexName = null, 
    string typeName = null,
    Refresh? refresh = null, 
    CancellationToken cancellationToken = default)
{
    Guard.Argument(document, nameof(document)).NotNull();

    await RemoveNullFieldsFromDocumentAsync(document, document.Id, indexName, typeName, cancellationToken);

    var response = await Client.UpdateAsync<T, object>(
        document.Id, 
        u => u.Doc(document)
            .Index(indexName ?? DocumentMappings.IndexStrategy)
            .Type(typeName ?? DocumentMappings.TypeName)
            .Refresh(refresh), 
        cancellationToken);

    var errorMessage = response.LogResponseIfError(_logger);

    return errorMessage.IsNullOrEmpty() ? Result.Ok() : Result.Fail(errorMessage);
}

public async Task<Result> UpdateAsync(
    string id, 
    object partialDocument, 
    string indexName = null, 
    string typeName = null,
    Refresh? refresh = null, 
    CancellationToken cancellationToken = default)
{
    Guard.Argument(partialDocument, nameof(partialDocument)).NotNull();
    Guard.Argument(id, nameof(id)).NotNull().NotEmpty().NotWhiteSpace();

    await RemoveNullFieldsFromDocumentAsync(partialDocument, id, indexName, typeName, cancellationToken);

    var response = await Client.UpdateAsync<T, object>(
        id, 
        u => u.Doc(partialDocument)
            .Index(indexName ?? DocumentMappings.IndexStrategy)
            .Type(typeName ?? DocumentMappings.TypeName)
            .Refresh(refresh), 
        cancellationToken);

    var errorMessage = response.LogResponseIfError(_logger);

    return errorMessage.IsNullOrEmpty() ? Result.Ok() : Result.Fail(errorMessage);
}

private async Task<Result> RemoveNullFieldsFromDocumentAsync(
    object document,
    string documentId,
    string indexName = null, 
    string typeName = null,
    CancellationToken cancellationToken = default)
{
    var result = Result.Ok();
    var allNullProperties = GetNullPropertyValueNames(document);
    if (allNullProperties.AnyAndNotNull())
    {
        var script = allNullProperties.Select(p => $"ctx._source.remove('{p}')").Aggregate((p1, p2) => $"{p1}; {p2};");
        result = await UpdateByQueryIdAsync(
                                        documentId, 
                                        script,
                                        indexName,
                                        typeName,
                                        cancellationToken: cancellationToken);
    }

    return result;
}

private static IReadOnlyList<string> GetNullPropertyValueNames(object document)
{
    var allPublicProperties =  document.GetType().GetProperties().ToList();

    var allObjects = allPublicProperties.Where(pi => pi.PropertyType.IsClass).ToList();

    var allNames = new List<string>();

    foreach (var propertyInfo in allObjects)
    {
        if (propertyInfo.PropertyType == typeof(string))
        {
            var isNullOrEmpty = ((string) propertyInfo.GetValue(document)).IsNullOrEmpty();
            if (isNullOrEmpty)
            {
                allNames.Add(propertyInfo.Name.ToCamelCase());
            }
        }
        else if (propertyInfo.PropertyType.IsClass)
        {
            if (propertyInfo.GetValue(document).IsNotNull())
            {
                var namesWithobjectName = GetNullPropertyValueNames(propertyInfo.GetValue(document))
                    .Select(p => $"{propertyInfo.PropertyType.Name.ToCamelCase()}.{p.ToCamelCase()}");
                allNames.AddRange(namesWithobjectName);
            }
        }
    }

    return allNames;
}

public async Task<Result> UpdateByQueryIdAsync(
    string documentId,
    string script,
    string indexName = null, 
    string typeName = null, 
    bool waitForCompletion= false,
    CancellationToken cancellationToken = default)
{
    Guard.Argument(documentId, nameof(documentId)).NotNull().NotEmpty().NotWhiteSpace();
    Guard.Argument(script, nameof(script)).NotNull().NotEmpty().NotWhiteSpace();

    var response = await Client.UpdateByQueryAsync<T>(
        u => u.Query(q => q.Ids(i => i.Values(documentId)))
                .Conflicts(Conflicts.Proceed)
                .Script(s => s.Source(script))
                .Refresh()
                .WaitForCompletion(waitForCompletion)
                .Index(indexName ?? DocumentMappings.IndexStrategy)
                .Type(typeName ?? DocumentMappings.TypeName), 
        cancellationToken);

    var errorMessage = response.LogResponseIfError(_logger);

    return errorMessage.IsNullOrEmpty() ? Result.Ok() : Result.Fail(errorMessage);
}