将两个字段合二为一并按新的组合字段排序

Question

我有以下文档（...意味着更多的属性和 getters 和 setters）

@Document
public class Equipment
{
...
private String name;
private String internalManufacturer;
private String externalManufacturer;
...
}

服务中的此方法，其中传递字段名称（代码）并设置排序。

private void setSorting(String code)
{
    ...
    List<AggregationOperation> pagedAndSortedQuery= new ArrayList<>(baseQuery);
    SortOperation sortOperation = sort(Sort.Direction.ASC, code);
    if (EquipmentsSortingField.MANUFACTURER.getCode().equals(code))
    {
        sortOperation = sort(sortingDirection, "internalManufacturer", "externalManufacturer");
        pagedAndSortedQuery.add(sortOperation);
    }
}

我想对 internalManufacturer 和 externalManufacturer 进行排序，就好像它们是一个字段一样，因为如果我在服务中这样做，首先我得到的结果是对 internalManufacturers 进行排序，然后对它们进行排序 externalManufacturers。重要的是，如果 externalManufacturer 为空，则 internalManufacturer 不是，反之亦然。

例如，我在数据库中有这个：

Equipment (externalManufacturer: John, internalManufacturer: null)
Equipment (externalManufacturer: null, internalManufacturer: Carlos)
Equipment (externalManufacturer: Ash, internalManufacturer: null)
Equipment (externalManufacturer: null, internalManufacturer: Victor)

使用我的代码，我将设备排序如下：

Equipment (externalManufacturer: null, internalManufacturer: Carlos)
Equipment (externalManufacturer: null, internalManufacturer: Victor)
Equipment (externalManufacturer: Ash, internalManufacturer: null)
Equipment (externalManufacturer: John, internalManufacturer: null)

我喜欢这样得到它们：

Equipment (externalManufacturer: Ash, internalManufacturer: null)
Equipment (externalManufacturer: null, internalManufacturer: Carlos)
Equipment (externalManufacturer: John, internalManufacturer: null)
Equipment (externalManufacturer: null, internalManufacturer: Victor)

总而言之，将两个字段都当作一个字段进行排序。

我该怎么做？提前致谢。

Answer 1

您应该使用

$addFields

生成一个新字段，这是内部和外部制造商的串联版本。然后使用这个新字段进行排序。沿着这些线的东西：

private void setSorting(String code)
{
    ...
    List<AggregationOperation> pagedAndSortedQuery= new ArrayList<>(baseQuery);
    SortOperation sortOperation = sort(Sort.Direction.ASC, code);
    if (EquipmentsSortingField.MANUFACTURER.getCode().equals(code))
    {
        AddFieldsOperation addFieldsOperation =
            Aggregation.addFields().addFieldWithValue(
                    "manufacturerString",
                    StringOperators.Concat.concatValueOf(ConditionalOperators.ifNull("internalManufacturer").then("")).concatValueOf(ConditionalOperators.ifNull("externalManufacturer").then(""))
            ).build();
        sortOperation = sort(sortingDirection, "manufacturerString");
        pagedAnsSortedQuery.add(addFieldsOperation);
        pagedAndSortedQuery.add(sortOperation);
    }
}

注意，我已经使用了新字段进行排序，并且还在管道中添加了

addField

阶段。请测试一下，我希望你明白了。