1

背景

我将GTFS数据存储在本地 mongodb 数据库中。

桌子calendar看起来像

field      | type
service_id | varchar
monday     | int (0 or 1)
tuesday    | int (0 or 1)
...
sunday     | int (0 or 1)

任务

我想service_id使用rmongodb.r

在 SQL 中，这将类似于：SELECT service_id FROM calendar WHERE monday = 1 OR tuesday = 1 OR ... OR friday = 1

细节

使用Robomongo GUI 时，查询是：

db.getCollection('calendar').find({"$or" : 
    [{'monday':1},
    {'tuesday':1},
    {'wednesday':1},
    {'thursday':1},
    {'friday':1}]
})

它返回 8 个文档（见图）

robomongo查询

因此，在r我试图构建or将返回相同结果的相同查询时，但我没有任何运气。

library(rmongodb)
library(jsonlite)
## connect to db
mongo <- mongo.create()
mongo.is.connected(mongo)
db <- "temp"

## days for which I want a service:
serviceDays <- c("monday","tuesday","wednesday","thursday","friday")

尝试 0：

## create list as the 'query' condition
ls <- list("$or" = 
         list("monday" = 1L, 
              "tuesday" = 1L, 
              "wednesday" = 1L, 
              "thursday" = 1L, 
              "friday" = 1L))

services <- mongo.find.all(mongo, "temp.calendar", query=ls)
## returns error:
Error in mongo.find(mongo, ns, query = query, sort = sort, fields = fields,  : 
  find failed with unknown error.

尝试1：

## paste the string together
js <- paste0('{"', serviceDays, '":[',1L,']}', collapse=",")
js <- paste0('{"$or" :[', js, ']}')
## this string has been validated at jsonlint.com

bs <- mongo.bson.from.JSON(js)
## run query
services <- mongo.find.all(mongo, "temp.calendar", query=bs)
## result
> services
list()    ## empty list

## manually writing the JSON string doesn't work either
# js <- '{"$or" : [{"monday":[1]},{"tuesday":[1]},{"wednesday":[1]},{"thursday":[1]},{"friday":[1]}]}'

尝试2：

## create the or condition using R code
l <- as.list(sapply(serviceDays, function(y) 1L))
bs <- mongo.bson.from.list(list("$or" = list(l)))
## run query
services <- mongo.find.all(mongo, "temp.calendar", query=bs)
## result
> length(services)
[1] 2    ## 2 documents returned

返回的两个文档是 for service_ids，其中所有 monday、tuesday、wednesday、thursday、friday = 1。即，它似乎使用了一个AND子句，而不是一个OR.

尝试 3：

## deconstruct the JSON string (attempt 1)
js <- fromJSON(js, simplifyVector=FALSE)
bs <- mongo.bson.from.list(js)

## run query
services <- mongo.find.all(mongo, "temp.calendar", query=bs)
## result
> services
list()    ## empty list

我的查询尝试有什么问题，R因为它阻止我获得与使用 Robomongo GUI 时相同的 8 个文档？

4

1 回答 1

2

我的“尝试 0”很接近，但我错过了更多的list论点。

ls <- list("$or" = list(list("monday" = 1L), 
                    list("tuesday" = 1L), 
                    list("wednesday" = 1L), 
                    list("thursday"= 1L), 
                    list("friday" = 1L)))
## json string:
> toJSON(ls)
{"$or":[{"monday":[1]},{"tuesday":[1]},{"wednesday":[1]},{"thursday":[1]},{"friday":[1]}]} 
## run query:
services <- mongo.find.all(mongo, "temp.calendar", query=ls)

## result
length(services)
[1] 8
于 2015-07-18T22:22:53.633 回答