How to make the event work only when you press the keyboard in pygame

Question

I want dinosaur to duck only when I press the space bar.
In other words, if I take off the space bar, I want the dinosaur to come back to the running position.
But now, when I press the space bar, the dinosaur goes down and doesn't come back up.
I really don't know how to fix it to implement that function.

import pygame
import os

pygame.init()

SCREEN_HEIGHT = 600
SCREEN_WIDTH = 1100
SCREEN = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

RUNNING = [pygame.image.load(os.path.join("Assets/Dino", "DinoRun1.png")),
           pygame.image.load(os.path.join("Assets/Dino", "DinoRun2.png"))]
JUMPING = pygame.image.load(os.path.join("Assets/Dino", "DinoJump.png"))
DUCKING = [pygame.image.load(os.path.join("Assets/Dino", "DinoDuck1.png")),
           pygame.image.load(os.path.join("Assets/Dino", "DinoDuck2.png"))]

class Dino:
    X_POS = 80
    Y_POS = 400
    Y_POS_DUCK = 430

    def __init__(self):
        self.run_img = RUNNING
        self.duck_img = DUCKING
        self.dino_run = True
        self.dino_duck = False

        self.step_index = 0
        self.image = self.run_img[0]
        self.dino_rect = self.image.get_rect()
        self.dino_rect.x = self.X_POS
        self.dino_rect.y = self.Y_POS

    def update(self, userInput):
        if self.dino_run:
            self.run()
        if self.dino_duck:
            self.duck()

        if self.step_index >= 10:
            self.step_index = 0

        if userInput[pygame.K_UP]:
            self.dino_run = True
            self.dino_duck = False
            self.Y_POS = 100
            self.Y_POS_DUCK = 130
        elif userInput[pygame.K_DOWN]:
            self.dino_run = True
            self.dino_duck = False
            self.Y_POS = 400
            self.Y_POS_DUCK = 430
        ***elif userInput[pygame.K_SPACE]:
            self.dino_run = False
            self.dino_duck = True***

    def run(self):
        self.image = self.run_img[self.step_index // 5]
        self.dino_rect = self.image.get_rect()
        self.dino_rect.x = self.X_POS
        self.dino_rect.y = self.Y_POS
        self.step_index += 1

    def duck(self):
        self.image = self.duck_img[self.step_index // 5]
        self.dino_rect = self.image.get_rect()
        self.dino_rect.x = self.X_POS
        self.dino_rect.y = self.Y_POS_DUCK
        self.step_index += 1

    def draw(self, SCREEN):
        SCREEN.blit(self.image, (self.dino_rect.x, self.dino_rect.y))


def main():
    run = True
    clock = pygame.time.Clock()
    player = Dino()

    while run:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False

        SCREEN.fill((255, 255, 255))
        userInput = pygame.key.get_pressed()

        player.draw(SCREEN)
        player.update(userInput)

        clock.tick(30)
        pygame.display.update()

Answer 1

In the update method add another if statement to check when spacebar is released:

...

elif userInput[pygame.K_SPACE]:
    self.dino_run = False
    self.dino_duck = True
if not userInput[pygame.K_SPACE]:
    self.dino_run = True
    self.dino_duck = False