How to make side collision in gravity game

Question

So I have a gravity game where the player can switch gravity and I'm having a problem with collision. when my player collides with the side of the platform, it will just go inside the platform but I want it to stop with it collides with the sides. I have a collision with the sides but that collision dose not work on my game, it only makes the player just freeze up. Some stuff I have tried is making it so when it is not colliding with my platform to stop moving but that also just froze my player, I also have tried telling it when it is colliding with the sides, but the player is always colliding with the platform.https://gyazo.com/0aa35529f5ecd7933f9e6c7c9d16f541

the collision I have tried using

px,py = playerman.x,playerman.y


if keys[pygame.K_a] and px > playerman.speed:
        px += playerman.speed


if keys[pygame.K_d] and px > playerman.speed:
        px -= playerman.speed

playerman.y = py
    if player_rect.collidelist(platform_rect_list) < 0:
    playerman.x = px

My code

import pygame
pygame.init()


# width and height of winddow
window = pygame.display.set_mode((700,500))


# window name
pygame.display.set_caption("Game")


#Player class
class Player:
    def __init__(self,x,y,width,height,color):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.color = color
        self.speed = 4
        self.rect = pygame.Rect(x,y,width,height)
    def draw(self):
        self.rect.topleft = (self.x,self.y)
        pygame.draw.rect(window,self.color,self.rect)


class Platform:
    def __init__(self,x,y,width,height,color):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.color = color
        self.rect = pygame.Rect(x,y,width,height)
    def draw(self):
        self.rect.topleft = (self.x,self.y)
        pygame.draw.rect(window,self.color,self.rect)


class Platform2:
    def __init__(self,x,y,width,height,color):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.color = color
        self.rect = pygame.Rect(x,y,width,height)
    def draw(self):
        self.rect.topleft = (self.x,self.y)
        pygame.draw.rect(window,self.color,self.rect)

           
# Colors
white = (255,255,255)
green = (255,0,0)

# class's cordination, size, and color

#Player
playerman = Player(300,250,40,70,white)


#Platform
platform1 = Platform(0,460,800,40,white)
platform2 = Platform(400,200,40,40,green)
#The top platform
platfom2 = Platform2(0,0,800,40,green)


# List's
platforms = [platform1,platform2]
platforms2 = [platfom2]


# drawing things in main loop
def redraw():
    # background color
    window.fill((0,0,0))


    # drawing the player in main loop
    playerman.draw()


    # Drawing all the bottom platforms in the main loop
    for Platform in platforms:
        Platform.draw()


    # Drawining all the top platforms in the main loop
    for Platform2 in platforms2:
        Platform2.draw()


# Timer for player falling
#fps for the game
fps = 30
clock = pygame.time.Clock()
up = True
down = False
run = True
while run:
    clock.tick(fps)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

            
    keys = pygame.key.get_pressed()
    px,py = playerman.x,playerman.y


    if down == False:
        for Platform in platforms2:
            if keys[pygame.K_SPACE] and playerman.rect.colliderect(Platform):
                up = True

                
    if up:
        playerman.y += 10
        fall = False


    for Platform in platforms:
        if playerman.rect.colliderect(Platform.rect):
            up = False


    if up == False and  keys[pygame.K_SPACE]:
        for Platform in platforms:
            if playerman.rect.colliderect(Platform.rect):
                down = True
                up = False

                
    if down:
        playerman.y -= 10
        playerman.direction = "tjump"
        fall = False


    for Platform in platforms2:
        if playerman.rect.colliderect(Platform.rect):
            down = False
            playerman.direction = "uidle"

   
    if keys[pygame.K_a] and px > playerman.speed:
        for Platform in platforms:
            Platform.x += playerman.speed
        for Platform2 in platforms2:
            Platform2.x += playerman.speed

                    
    elif keys[pygame.K_d] and px < 2000 - playerman.width + playerman.speed:
        for Platform in platforms:
            Platform.x -= playerman.speed
        for Platform2 in platforms2:
            Platform2.x -= playerman.speed
                

                
    redraw()
    pygame.display.update()
pygame.quit()

Answer 1

The easiest way is to move the object and check if it collides with something or its out of bounds and roll back the movement; the game looked fun to make, so i made my own version, i hope it comes usefull to you.

import random
import pygame

FPS = 30
WX, WY = 700, 500

pygame.init()
pygame.display.set_caption("Game")
window = pygame.display.set_mode((WX, WY))

class Player(pygame.Rect):
    def __init__(self, x1, y1, x2, y2, color):
        pygame.Rect.__init__(self, x1, y1, x2, y2)
        self.color = color
        self.speed = 4
        self.move_hor = 0
        self.move_ver = 0

    def draw(self):
        pygame.draw.rect(window, self.color, self)

class Platform(pygame.Rect):
    def __init__(self, x1, y1, x2, y2):
        pygame.Rect.__init__(self, x1, y1, x2, y2)
        self.color = self.random_color()

    @staticmethod
    def random_color():
        color = [0, 0, 0]
        for i in range(3):
            color[i] = random.randint(80, 230)
        return color

    def draw(self):
        pygame.draw.rect(window, self.color, self)

class Game:

    def __init__(self):
        self.player = Player(300, 250, 50, 50, (255, 255, 255))
        self.world_obj = [
            Platform(0, 0, WX, 30),
            Platform(0, WY - 30, WX, WY),
            Platform(300, 100, 305, 105)
        ]
        self.clock = pygame.time.Clock()
        self.grav_sw = 0
        self.gravity = 1
        self.grav_sp = 4
        self.run = True

    def handle_events(self):
        self.player.move_hor = 0
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                self.run = False

        keys = pygame.key.get_pressed()
        remt = pygame.time.get_ticks()
        # A delay is required to prevent a double inversion
        if keys[pygame.K_SPACE] and remt - self.grav_sw >= 150:
            self.grav_sw = remt
            if self.gravity:
                self.gravity = 0
            else:
                self.gravity = 1

        if keys[pygame.K_a] or keys[pygame.K_LEFT]:
            self.player.move_hor = 2
        elif keys[pygame.K_d] or keys[pygame.K_RIGHT]:
            self.player.move_hor = 1

    def handle_position(self):
        if self.player.move_hor != 0:
            if self.player.move_hor == 1:
                if self.player.right + self.player.speed <= WX:
                    self.player.right += self.player.speed
            else:
                if self.player.left - self.player.speed >= 0:
                    self.player.left -= self.player.speed

        if self.gravity == 1:
            if self.player.bottom + self.grav_sp <= WY:
                self.player.bottom += self.grav_sp
        else:
            if self.player.top - self.grav_sp >= 0:
                self.player.top -= self.grav_sp

        for index in self.player.collidelistall(self.world_obj):
            o = self.world_obj[index]
            if self.gravity == 1:
                if self.player.top >= o.bottom:
                    self.player.top += self.grav_sp
                elif self.player.bottom >= o.top:
                    self.player.top -= self.grav_sp
            else:
                if self.player.top <= o.bottom:
                    self.player.top += self.grav_sp
                elif self.player.bottom <= o.top:
                    self.player.top -= self.grav_sp

            #TODO: x-axis collision

    def handle_render(self):
        window.fill((0, 0, 0))
        for obj in self.world_obj:
            obj.draw()
        self.player.draw()

    def mainloop(self):
        while self.run:
            self.handle_events()
            self.handle_position()
            self.handle_render()
            pygame.display.flip()
            self.clock.tick(FPS)
        pygame.quit()


if __name__ == '__main__':
    game = Game()
    game.mainloop()