R -How to pass value in mongolite Query

问题

I'm using mongolite package to connect and retrieve data from MongoDB.How to pass value in mongolite find query

##connecting mongodb

library(mongolite)

mongo<-mongolite::mongo(collection = "Sample", db = "Test", url = 
                          "mongodb://User:123@Wyyuyu:13333/ty2_U",verbose = TRUE)

## getting all data from collection data from collection below query is working fine.

values <- mongo$find()

## But I want to filter specific value by passing value.

 for(i in c("process","check","queue"))
{    

   values <- mongo$find('{"field" : i}',)
}

if I tried above code i'm getting getting below issues . please help me to resolve

Error: Invalid JSON object: {"field" : i}

回答1:

Given your i is a variable, you need to create the string using something like paste0:

values <- mongo$find(paste0('{"field" : ', i, '}') )

but rather than a loop you could also use

values <- mongo$find('{"field" : { "$in" : [ "process", "check", "queue" ] } }')

来源：https://stackoverflow.com/questions/47069411/r-how-to-pass-value-in-mongolite-query