Can't iterate over Time objects in Ruby - ruby

Question

I am writing an appointment form that will let the user choose a date. It will then take the date and check against a Google Calendar what time slots are available for that date within a range of 30 minutes time intervals from 10:00am to 5:00pm.
Within my Calendar class, I have an available_times method:
def available_times(appointment_date)
appointment_date_events = calendar.events.select { |event| Date.parse(event.start_time) == appointment_date }
conflicts = appointment_date_events.map { |event| [Time.parse(event.start_time), Time.parse(event.end_time)] }
results = resolve_time_conflicts(conflicts)
end
This method takes a date and grabs the start_time and end_time for each event on that date. It then calls resolve_time_conflicts(conflicts):
def resolve_time_conflicts(conflicts)
start_time = Time.parse('10:00am')
available_times = []
14.times do |interval_multiple|
appointment_time = (start_time + interval_multiple * (30 * 60))
available_times << appointment_time unless conflicts.each{ |conflict| (conflict[0]..conflict[1]).include?(appointment_time)}
end
available_times
end
A 'Can't iterate over Time' error is being thrown when I attempt to iterate over the conflicts array. I tried to call to_enum on the conflicts array but am still getting the same error.
All of the other questions I saw on SO were referencing the step method, which doesn't seem applicable to this case.
Update:
Thanks #caryswoveland and #fivedigit. I combined both of your answers, which were very helpful for different aspects of my solution:
def available_times(appointment_date)
appointment_date_events = calendar.events.select { |event| Date.parse(event.start_time) == appointment_date }
conflicts = appointment_date_events.map { |event| DateTime.parse(event.start_time)..DateTime.parse(event.end_time) }
results = resolve_time_conflicts(conflicts)
end
def resolve_time_conflicts(conflicts)
date = conflicts.first.first
start_time = DateTime.new(date.year, date.month, date.day, 10, 00).change(offset: date.zone)
available_times = []
14.times do |interval_multiple|
appointment_time = (start_time + ((interval_multiple * 30).minutes))
available_times << appointment_time unless conflicts.any? { |conflict| conflict.cover?(appointment_time)}
end
available_times
end

Answer 1

Exception
#fivedigit has explained why the exception was raised.
Other problems
You need any? where you have each:
appointment_times = []
#=> []
appointment = 4
#=> 4
conflicts = [(1..3), (5..7)]
#=> [1..3, 5..7]
appointment_times << 5 unless conflicts.each { |r| r.cover?(appointment) }
#=> nil
appointment_times
#=> []
appointment_times << 5 unless conflicts.any? { |r| r.include?(appointment) }
#=> [5]
appointment_times
#=> [5]
I suggest you covert appointment_time to a Time object, make conflicts and array of elements [start_time, end_time] and then compare appointment_time to the endpoints:
...unless conflicts.any?{ |start_time, end_time|
start_time <= appointment_time && appointment_time <= end_time }
Aside: Range#include? only looks at endpoints (as Range#cover? does) when the endpoints are "numeric". Range#include? need only look at endpoints when they are Time objects, but I don't know if Ruby regards Time objects as "numeric". I guess one could look at the source code. Anybody know offhand?
Alternative approach
I would like to suggest a different way to implement your method. I will do so with an example.
Suppose appointments were in blocks of 15 minutes, with the first block being 10:00am-10:15am and the last 4:45pm-5:00pm. (blocks could be shorter, of course, as small as 1 second in duration.)
Let 10:00am-10:15am be block 0, 10:15am-10:30am be block 1, and so on, until block 27, 4:45pm-5:00pm.
Next, express conflicts as an array of block ranges, given by [start, end]. Suppose there were appointments at:
10:45am-11:30am (blocks 3, 4 and 5)
1:00pm- 1:30pm (blocks 12 and 13)
2:15pm- 3:30pm (blocks 17, 18 and 19)
Then:
conflicts = [[3,5], [12,13], [17,19]]
You must write a method reserved_blocks(appointment_date) that returns conflicts.
The remaining code is as follows:
BLOCKS = 28
MINUTES = ["00", "15", "30", "45"]
BLOCK_TO_TIME = (BLOCKS-1).times.map { |i|
"#{i<12 ? 10+i/4 : (i-8)/4}:#{MINUTES[i%4]}#{i<8 ? 'am' : 'pm'}" }
#=> ["10:00am", "10:15am", "10:30am", "10:45am",
# "11:00am", "11:15am", "11:30am", "11:45am",
# "12:00pm", "12:15pm", "12:30pm", "12:45pm",
# "1:00pm", "1:15pm", "1:30pm", "1:45pm",
# "2:00pm", "2:15pm", "2:30pm", "2:45pm",
# "3:00pm", "3:15pm", "3:30pm", "3:45pm",
# "4:00pm", "4:15pm", "4:30pm", "4:45pm"]
def available_times(appointment_date)
available = [*(0..BLOCKS-1)]-reserved_blocks(appointment_date)
.flat_map { |s,e| (s..e).to_a }
last = -2 # any value will do, can even remove statement
test = false
available.chunk { |b| (test=!test) if b > last+1; last = b; test }
.map { |_,a| [BLOCK_TO_TIME[a.first],
(a.last < BLOCKS-1) ? BLOCK_TO_TIME[a.last+1] : "5:00pm"] }
end
def reserved_blocks(date) # stub for demonstration.
[[3,5], [12,13], [17,19]]
end
Let's see what we get:
available_times("anything")
#=> [["10:00am", "10:45am"],
# ["11:30am", "1:00pm"],
# [ "1:45pm", "2:15pm"],
# [ "3:00pm", "5:00pm"]]
Explanation
Here is what's happening:
appointment_date = "anything" # dummy for demonstration
all_blocks = [*(0..BLOCKS-1)]
#=> [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
# 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27]
reserved_ranges = reserved_blocks(appointment_date)
#=> [[3, 5], [12, 13], [17, 19]]
reserved = reserved_ranges.flat_map { |s,e| (s..e).to_a }
#=> [3, 4, 5, 12, 13, 17, 18, 19]
available = ALL_BLOCKS - reserved
#=> [0, 1, 2, 6, 7, 8, 9, 10, 11, 14, 15, 16, 20, 21, 22, 23, 24, 25, 26, 27]
last = -2
test = false
enum1 = available.chunk { |b| (test=!test) if b > last+1; last = b; test }
#=> #<Enumerator: #<Enumerator::Generator:0x00000103063570>:each>
We can convert it to an array to see what values it would pass into the block if map did not follow:
enum1.to_a
#=> [[true, [0, 1, 2]],
# [false, [6, 7, 8, 9, 10, 11]],
# [true, [14, 15, 16]],
# [false, [20, 21, 22, 23, 24, 25, 26, 27]]]
Enumerable#chunk groups consecutive values of the enumerator. It does so by grouping on the value of test and flipping its value between true and false whenever a non-consecutive value is encountered.
enum2 = enum1.map
#=> #<Enumerator: #<Enumerator: (cont.)
#<Enumerator::Generator:0x00000103063570>:each>:map>
enum2.to_a
#=> [[true, [0, 1, 2]],
# [false, [6, 7, 8, 9, 10, 11]],
# [true, [14, 15, 16]],
# [false, [20, 21, 22, 23, 24, 25, 26, 27]]]
You might think of enum2 as a "compound" enumerator.
Lastly, we convert the second element of each value of enum2 that is passed into the block (the block variable a, which equals [0,1,2] for the first element passed) to a range expressed as a 12-hour time. The first element of each value of enum2 (true or false) is not used, so so I've replaced its block variable with an underscore. This provides the desired result:
enum2.each { |_,a|[BLOCK_TO_TIME[a.first], \
(a.last < BLOCKS-1) ? BLOCK_TO_TIME[a.last+1] : "5:00pm"] }
#=> [["10:00am", "10:45am"],
# ["11:30am", "1:00pm"],
# [ "1:45pm", "2:15pm"],
# [ "3:00pm", "5:00pm"]]

Answer 2

The issue comes from this bit:
(conflict[0]..conflict[1]).include?(appointment_time)
# TypeError: can't iterate from Time
You're creating a range of times and then checking if appointment_time falls within the range. This is what causes the error you're experiencing.
Instead of include?, you should use cover?:
(conflict[0]..conflict[1]).cover?(appointment_time)
This assumes that conflict[0] is the earliest time.

Answer 3

Convert your range from a range of times to a range of integers:
range = (conflict[0].to_i..conflict[1].to_i)
Then use the === operator as you used the include?:
conflict === appointment_time
EDIT: You can also obviously convert appointment_time to integer and still use include? since the range is now just an integer range.