Grouped barplots using ggplot

[ClawV]

I have this dataset

month = c("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")
Purchase = c(110,120,60,84,66,92,32,53,77,100,48,79)
Sales = c(90,120,80,64,69,98,41,39,65,98,57,69)
df = data.frame(month, Purchase, Sales)

I want to have a grouped barplot of month vs Purchase and Sales. Basically x axis should be Month and Y axis should be count and in the barplot, I need to have Purchase and Sales grouped next to each other per month.

   #Code for single plot
ggplot(data=df,aes(y=Purchase, x=month)) + geom_bar(stat = "identity")
#But when I do this, the plot is not correct. 
ggplot(data=df,aes(y=Purchase, x=month,fill=Sales)) + geom_bar(stat="identity", position = "dodge")

[williaml]

Something like this?

df2 <- df %>% 
  pivot_longer(-month, names_to = "type", values_to = "value") %>% 
  mutate(month = factor(month), levels = month.abb)

ggplot(df2, aes(month, value, fill = type)) +
  geom_col(position = "dodge") + 
  scale_x_discrete(limits = month.abb) +
  theme(legend.position = "bottom")

[ClawV]

This is what I am looking for. But the issue is if I run the first line of code as is, I get "Error:Invalid index:out of bounds."
But this code works

df2 <- df %>%  pivot_longer(-month, names_to = "type", values_to = "value")
ggplot(df2, aes(month, value, fill = type)) + geom_col(position = "dodge") + 
  scale_x_discrete(limits = month.abb)

Edit: If I add mutate(month = factor(month)), I get the plot. I think levels=month.abb is causing "Out of bounds error".
The thing is irrespective of mutate, I get the pIot and see no difference in the result. I am not sure what mutate is doing.

[williaml]

It was meant to put the months in order, because it wasn't showing in the right order in my first graph. Good that it is working.