我想在调用日期后立即验证日期的输入，以使用户不会输入全部三个，然后再次收到错误/提示输入日期的提示，但是我想不出一种方法去做。我是否需要重组，或者有什么方法可以丢失？
我有一个类对象library("shiny")
library("dplyr")
library("ggplot2")
shinyApp(
ui = fluidPage(
# Layout with sidebar
sidebarLayout(
## Sidebar -----
sidebarPanel(
# > some example input on sidebar -----
selectInput("choice", "Choose species",
choices = c("none",
unique(as.character(iris$Species))),
selected = "setosa")
), # closes Sidebar-Panel
# Main-Panel ------
mainPanel(
br(),
tabsetPanel(
# > Plot -------
tabPanel("Plot tab",
value = 1,
plotOutput("plot_text")
), # closes tabPanel
id = "tabselected", type = "pills"
) # closes tabsetPanel
) # closes mainPanel
) # closes sidebarLayout
), # closes fluidPage
# Server ------
server = function(input, output, session){
data_indicator <- reactive({
validate(
need(input$choice %in% iris$Species, "No plot available for chosen filter criteria!")
)
iris %>%
mutate(Species = as.character(Species)) %>%
filter(Species == input$choice)
})
output$plot_text <- renderPlot({
# Alternativly use validate here in the following way:
# validate(
# need(input$choice %in% data_indicator()$Species, "No plot available for chosen filter criteria!")
# )
ggplot(data_indicator(), aes(x = Species, y = Sepal.Length)) +
geom_col()
})
} # Closes server
) # Closes ShinyApp
定义如下：
task然后通过定义如下的函数class task:
def __init__(self, name, due, category):
self.name = name
self.due = datetime.strptime(due, '%B %d %Y %I:%M%p')
self.category = category
def expand(self): # returns the contents of the task
return str(self.name) + " is due in " + str((self.due - datetime.now()))
创建该类：
addTask如下收集输入：
def addTask(name, due, category):
newTask = task(name, due, category)
data.append(newTask)
with open('./tasks.txt', 'wb') as file:
pickle.dump(data, file)
load_data()
list_tasks()
答案 0 :(得分：1)
一种方法是在try / except块中将日期时间传递到addTask之前对其进行验证。
def ask():
while True:
arg = input("").lower()
if arg == "add":
task = input("What is the task? ")
due = input("When's it due? ")
category = input("What's the category? "))
try:
due = datetime.strptime(due, '%B %d %Y %I:%M%p')
except ValueError:
raise ValueError("Incorrect date format")
addTask(task, due, category)
elif arg =="help":
help()
elif arg =="list":
list_tasks()
else:
print("Command not recognized. Type 'help' for a list of commands.")
还有更强大的验证方法，例如使用棉花糖库，但这对于您正在研究的内容可能会显得过大。