Date converted into month, day, week etc in shiny application - r

Question

I am very new in shiny application.I have already build customer prediction algorithm (linear regression) using R. In that case, I extracted date into month, days, week etc.and considered as independent variable. Now, I would like to build shiny application for the same. Application will take date as input and output will be the predicted customer number. I have date wise historical customer data. for analysis, I produced month, week, day as independent variable and number of customer is my dependent variable. I trained linear regression for prediction purpose. I faced the problem to convert new input date into month, day, week etc.
so that I can predict new date for number of customer. Kindly help me in this regards.
Prediction
library(caret)
mydata <- read.csv("main.csv", header = TRUE)
mydata$date <- as.Date(mydata$date, format = "%m/%d/%Y")
mydata$month <- strftime(mydata$date, "%m")
mydata$day <- strftime(mydata$date, "%d")
mydata$week <- strftime(mydata$date, "%w")
mydata$week_year <- strftime(mydata$date, "%W")
mydata$month <- as.factor(mydata$month)
mydata$day <- as.factor(mydata$day)
mydata$week <- as.factor(mydata$week)
mydata$week_year <- as.factor(mydata$week_year)
mydata <- mydata[c(1, 3, 4, 5, 6)]
ind <- sample(2, nrow(mydata), replace = TRUE, prob=c(0.7, 0.3))
trainset = mydata[ind == 1,]
testset = mydata[ind == 2,]
pred_cus <-glm(no_customer~month+week+day,
data = trainset,
family = gaussian)
testset$prediction <- predict(pred_cus, testset)
RMSE(testset$prediction, testset$no_customer)
structure(list(
Customer = c(94L, 61L, 51L, 28L, 29L, 56L, 99L, 87L, 88L, 71L, 40L, 33L,
57L, 71L, 84L, 81L, 57L, 31L, 28L, 77L, 84L, 69L, 76L, 65L,
36L, 26L, 60L, 70L, 82L, 81L, 49L, 54L, 18L, 66L, 89L, 69L,
61L, 88L, 40L, 25L, 82L, 77L, 88L, 72L, 75L, 40L, 24L, 79L,
67L, 82L, 55L, 78L, 44L, 14L, 76L, 89L, 87L, 93L, 64L, 23L,
34L, 65L, 83L, 92L, 87L, 105L, 40L, 32L, 80L, 76L, 83L, 76L,
70L, 43L, 33L, 75L, 75L, 70L, 55L, 70L, 36L, 13L, 64L, 72L,
79L, 62L, 52L, 30L, 32L, 85L, 87L, 84L, 93L, 73L, 21L, 19L,
101L, ''''''''''''''''''''''''''''''''
Label = c("1/1/2016", "1/10/2016", "1/11/2016", "1/12/2016", "1/13/2016",
"1/14/2016", "1/15/2016", "1/16/2016", "1/17/2016", "1/18/2016",
"1/19/2016", "1/2/2016", "1/20/2016", "1/21/2016", "1/22/2016",
"1/23/2016", "1/24/2016", "1/25/2016", "1/26/2016", "1/27/2016",
"1/28/2016", "1/29/2016", "1/3/2016", "1/30/2016", "1/31/2016",
"1/4/2016", "1/5/2016", "1/6/2016", "1/7/2016", "1/8/2016",
"1/9/2016", "10/1/2015", "10/10/2015", "10/11/2015", "10/12/2015",
"10/13/2015", "10/14/2015", "10/15/2015", "10/16/2015", "10/17/2015",
"10/18/2015", "10/19/2015", "10/2/2015", "10/20/2015", "10/21/2015",
"10/22/2015", "10/23/2015", "10/24/2015",
class = "factor")
),
.Names = c("Customer", date"),
class = "data.frame",
row.names = c(NA, -457L)
)