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json 字段关键值核心数据核心数据
原标题:core data for key-value in json field

在我的应用程序中, 我需要查询核心数据, 我有一个表格, 包含一个存储 json 字符串的字段。 现在我需要查询此表格, 以查找此字段中含有特定关键值对的条目。 我已经尝试过用类似表达式解决这个问题, 但自从 WILDCARDS Do Match the NewLINE 运行得如此不顺利 。 现在, 我困在想通MatchES 操作中要使用哪个正则 。

键和值的子字符串是已知的,我只需要找到含有它们的条目,没有其他 :)

最佳回答

用正方形解析它 :

    for(NSString* value in values)
{
    if(value.length > 0)
    {
        if(i > 0)
        {
            [query appendString:@" OR "];

        }
        [query appendFormat:@" (json_data MATCHES[c]  .*?"%@\":\"([^"]*)%@([^"]*)".*? )",key,value];
        i++;
    }

}
问题回答

您可以向该实体写入获取器属性, 它返回的只是一个普通字符串, 而不是json 字符串, 例如 :

- (NSString *)stringRepresentation
{ 
  NSError *error = nil; 
  NSData* data=[self.jsonStringProperty dataUsingEncoding:NSUTF8StringEncoding];
  NSString *string = [JSONObjectWithData:data options:0 error:&error];
  if (error) {
   ... // error handling
  }
  return string;
}

然后您就可以在该属性上使用类似表达式的查询





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