How do I convert an uploaded CSV file into a data frame?

[NickNicolaou2129]

I have created a file upload section that uploads and reads CSV files as a table:

ui <- fluidPage(

titlePanel("Upload Transaction Data Set"),

 sidebarLayout(

    sidebarPanel(

  fileInput("file1", "Choose CSV File",
            multiple = FALSE,
            accept = c("text/csv",
                     "text/comma-separated-values,text/plain",
                     ".csv")),
  tags$hr(),

  checkboxInput("header", "Header", TRUE),

  radioButtons("sep", "Separator",
               choices = c(Tab = "\t"),
               selected = "\t"),

  radioButtons("quote", "Quote",
               choices = c(None = "",
                           "Double Quote" = '"',
                           "Single Quote" = "'"),
               selected = '"'),

  tags$hr(),

   radioButtons("disp", "Display",
               choices = c(Head = "head",
                           All = "all"),
               selected = "head")

),

mainPanel(

  tableOutput("contents")
       )
)

I have also created linear regression models that takes input from a data set:

thedata <- readxl::read_xlsx("data/transactionDataAlteredXLSX.xlsx")

set.seed(2)
library(caTools)
split <- sample.split(thedata, SplitRatio=0.7)

train <- subset(thedata, split=TRUE)
Actual <- subset(thedata, split=FALSE)


# Create the model
Model <- lm(Class ~.,data=train)
#Prediction
Prediction <- predict(Model, Actual)

#Comparing predicted vs actual model
plot(Actual$Class,type = "l",lty= 1.8,col = "red")
lines(Prediction, type = "l", col = "blue")
plot(Prediction,type = "l",lty= 1.8,col = "blue")
#Finding Accuracy

shinyApp(ui, server)

How do I make the linear regression models form the output of the file upload, and not from the dataset 'thedata'? I have suspicions that I need to convert the uploaded file to a data frame, and then use it as an object for the linear regression.

Thanks.