Transform number chain into date

I am trying to transform a list of numbers (e.g. 20200119) into a valid date (here: 2020-01-19)

This is my trial data:

df <- data.frame(c(20200119, 20180718, 20180729, 20150502, 20010301))
colnames(df)[1] = "Dates"

And this is what I tried so far:

df <- as_date(df)
df <- as.Date.numeric(df)
df <- as.Date.factor(df)

Neither of them works unfortunately.
I also tried to seperate the numbers, but I couldn’t achieve either.

Can somebody help me?

>Solution :

Convert it to a character and convert it then to a Date with given format %Y%m%d:

as.Date(as.character(df$Dates), "%Y%m%d")
#[1] "2020-01-19" "2018-07-18" "2018-07-29" "2015-05-02" "2001-03-01"