Question

我们尝试使用$ project（聚合）和包含字段（查询），但它只包含Id和Filtered字段。我们的预期结果是文档中的所有字段以及按区域设置（动态密钥）过滤的嵌入文档。

示例：

categories:[{
_id: 1,
categoryNumber: "12345",
locale: {
                en_US: {
                                name: "Category Name in US"
                },
                fr_FR: {
                                name: "Category Name in French"
                }
}
},
{
_id: 2,
categoryNumber: "6789",
locale: {
                en_GB: {
                                name: "Category Name in UK"
                }
}
}]

Expected Result:

Filter records by locale: en_US(Embedded document key)

[{
_id: 1,
categoryNumber: "12345",
locale: {
                en_US: {
                                name: "Category Name in US"
                }
}
}]

查询：

AggregationOperation matchOperaion = match(where(Constants.ID).is(clientProdTypeId));

                              AggregationExpression aggregationExpression = (AggregationOperationContext) -> {
                                             Map<String, Object> conditionMap = new HashMap<>();
                                             conditionMap.put("input", "$locale.en_US.name"); 
                                             conditionMap.put("as", Constants.NAME);
                                             conditionMap.put("cond", new BasicDBObject());
                                             return new BasicDBObject("$filter", conditionMap);
                              };

                              AggregationOperation projectionOperation;


                                             projectionOperation = project().and(aggregationExpression).as(Constants.METADATA)
                                                                           .andInclude(Constants.CLIENT_ID, Constants.PRODUCT_TYPE_ID,Constants.STATUS);


                              AggregationResults<CategoryDTO> result;

                              try {
                                             result = mongoOperations.aggregate(newAggregation(matchOperaion, projectionOperation),
                                                                           Category.class, CategoryDTO.class);
                              } catch (IllegalArgumentException | DataAccessException e) {
                                             LOGGER.error("Error while fetching client product type", e);

                              }
                              return result.getUniqueMappedResult();

Answer 1

而不是$project使用$addFields。 $project仅传递指定字段，$addFields传递所有字段以及新/计算/字段。

Answer 2

您可以在3.4版本中使用以下聚合表达式。

$objectToArray将locale转换为键值对，并将$filter转换为语言环境输入，$arrayToObject转换回动态键。

  AggregationExpression aggregationExpression = (AggregationOperationContext) -> {
     Map<String, Object> conditionMap = new HashMap<>();
     conditionMap.put("input", new BasicDBObject("$objectToArray", "$locale"));
     conditionMap.put("as", "result");
     conditionMap.put("cond", new BasicDBObject("$$result.k", "en_US"));
     return new BasicDBObject("$arrayToObject", new BasicDBObject("$filter", conditionMap));
   };

Answer 3

db.collection.find({locale.en_US:{$exists : true}});

需要在不使用“查询中包含字段”的情况下获取所有字段以及“聚合”字段

3 个答案: