有没有办法在无痛中按字母顺序比较字符串答案

【问题标题】：Is there a way to compare string alphabetically in painless有没有办法在无痛中按字母顺序比较字符串
【发布时间】：2019-01-25 23:01:29
【问题描述】：

我想无痛执行这种操作：

if (_value >= 'c)' { 
 return _value 
} else { 
 return '__BAD__' 
}

value 是一个字符串，我想要以下行为：

如果值为foo 我想用__BAD__ 替换它如果值为bar，我想保留bar。只有在“c”之后按字母顺序排列的值才应设置为__BAD__。

我遇到了这个异常：

"lang": "painless",
"caused_by": {
  "type": "class_cast_exception",
  "reason": "Cannot apply [>] operation to types [java.lang.String] and [java.lang.String]."
}

有没有办法在无痛的情况下进行字符串之间的字符串字母比较？

我的文件正在查找：

{
  "id": "doca",
  "categoryId": "aaa",
  "parentNames": "a$aa$aaa"
},
{
  "id": "docb",
  "categoryId": "bbb",
  "parentNames": "a$aa$bbb"
},
{
  "id": "docz",
  "categoryId": "zzz",
  "parentNames": "a$aa$zzz"
}

我的查询是这样的：

{
  "query": {
    "bool": {
      "filter": []
    }
  },
  "size": 0,
  "aggs": {
    "catNames": {
      "terms": {
        "size": 10000,
        "order": {
          "_key": "asc"
        },
        "script": {
              "source": "if(doc['parentNames'].value < 'a$aa$ccc') {return doc['parentNames'].value} return '__BAD__'",
              "lang": "painless"
            }
      },
      "aggs": {
        "sort": {
          "bucket_sort": {
            "size": 2
          }
        },
        "catId": {
          "terms": {
            "field": "categoryId",
            "size": 1
          }
        }
      }
    }
  }
}

我期待结果：

{
  "took": 29,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 3,
    "max_score": 0,
    "hits": []
  },
  "aggregations": {
    "catNames": {
      "doc_count_error_upper_bound": 0,
      "sum_other_doc_count": 0,
      "buckets": [
        {
          "key": "__BAD__",
          "doc_count": 1,
          "catId": {
            "buckets": [
              {
                "key": "aaa",
                "doc_count": 1
              }
            ]
          }
        },
        {
          "key": "a$aa$bbb",
          "doc_count": 1,
          "catId": {
            "buckets": [
              {
                "key": "bbb",
                "doc_count": 1
              }
            ]
          }
        },
        {
          "key": "a$aa$zzz",
          "doc_count": 1,
          "catId": {
            "buckets": [
              {
                "key": "zzz",
                "doc_count": 1
              }
            ]
          }
        }
      ]
    }
  }
}

【问题讨论】：

标签： elasticsearch elasticsearch-painless

【解决方案1】：

其实我可以使用java.lang.String的compareTo函数。

if (_value.compareTo('c') > 0) { 
 return _value 
} else { 
 return '__BAD__' 
}

我的查询变成了：

{
  "query": {
    "bool": {
      "filter": []
    }
  },
  "size": 0,
  "aggs": {
    "catNames": {
      "terms": {
        "size": 10000,
        "order": {
          "_key": "asc"
        },
        "script": {
              "source": "if(doc['parentNames'].value.compareTo('a$aa$ccc')) {return doc['parentNames'].value} return '__BAD__'",
              "lang": "painless"
            }
      },
      "aggs": {
        "sort": {
          "bucket_sort": {
            "size": 2
          }
        },
        "catId": {
          "terms": {
            "field": "categoryId",
            "size": 1
          }
        }
      }
    }
  }
}

【讨论】：