1

我想编写一个函数来查询带有参数的 mongodb 数据库。

get_price = function(codes, start_date, end_date){
        query_string = '[{"$match":{"filedA":{"$in": codes}, "start_date":start_date, "end_date":end_date}},
                         {"$project":{"_id":0 }}
                      ]'
}


con$aggregate(pipeline=query_string)

但是构建查询字符串很麻烦。

提前致谢。

4

1 回答 1

0

我正在使用这个：

{
  bool_vector <- c(TRUE,FALSE)
  date_vector <- as.Date(c("2020-05-31","2020-06-30","2020-07-31") )
  str_vector <- c("string1","string2")
}

{
  bool_function<-function(bool_vector) {
  bool_json  <- ifelse(length(tolower(as.character(bool_vector))) %in% 2,
                       '{ "$in" : [ true, false ] }',tolower(as.character(bool_vector) 
                                                             ) 
                       )
  # as the field is named bool, the search vector should be bool_vector
  bool_field <- gsub("(.*)_.*","\\1",quote(bool_vector) ) 
  bool_json2 <- paste0('"',bool_field,'":',bool_json)
  return(bool_json2)
}

date_function<- function(date_vector) {
  # as the field is named date, the search vector should be date_vector
  date_field <- gsub("(.*)_.*","\\1",quote(date_vector) ) 
  
  date_json <- paste0('"',date_field,'":{"$gt":{"$date":"'
                      ,min(date_vector),'T00:00:00Z"},"$lt":{"$date":"'
                      ,max(date_vector),'T23:59:59Z"}}'
  )
  return(date_json)
}

str_function<-function(str_vector) {
  # as the field is named str, the search vector should be str_vector
  str_field <- gsub("(.*)_.*","\\1",quote(str_vector) ) 
  str_json   <- paste0("\"",paste0(str_vector,collapse= "\",\""),"\"")
  str_json_2 <- paste0('"',str_field,'":{"$in" : [',str_json,'] }')
  return(str_json_2)
}
}

vec_list <- mget(ls(pattern = "vector"))

make_query <- function(vec_list) {
json_list<-list()
i=0
for(vec in vec_list){
  i = i+1
  if(class(vec)=="logical"){
    json_list[[i]] <-bool_function(vec)
  } else if (class(vec)=="character") {
    json_list[[i]] <- str_function(vec)
  } else if (class(vec)=="Date") {
    json_list[[i]] <- date_function(vec)    
  }
}
query <- paste0("{",paste0(unlist(json_list),collapse = ","),"}")
return(query)
}

make_query(vec_list)

"{\"bool\":{ \"$in\" : [ true, false ] },\"date\":{\"$gt\":{\"$date\":\"2020-05-31T00:00:00Z\"},\"$lt\":{\"$date\":\"2020-07-31T23:59:59Z\"}},\"str\":{\"$in\" : [\"string1\",\"string2\"] }}"
于 2021-09-06T16:43:54.110 回答