Building a calendar app with Nextjs, mongodb, react-big-calendar and redux.

Calendar app built with Nextjs

Before we begin, here is the code and demo of what we are building

• Github Repository: https://github.com/himohitmehta/calendar-app-tutorial
• Demo : https://calendar-app.mohitmehta.dev/

In this tutorial, we will be building a calendar app with nextjs, react-big-calendar, material-ui, redux, and mongodb.

Create the project

In order to build our project, we need to run the following command:

npx creat-next-app calendar-app-nextjs

Once the project is created after the above mentioned command you need to open the folder in VS Code or any IDE of your choice.

Now run the following command to add the dependencies to your project

npm install @reduxjs/toolkit date-fns date-fns-tz mongoose react-big-calendar react-redux redux redux-logger redux-persist redux-saga redux-thunk @emotion/styled @emotion/react @mui/material

This command will add the required dependencies to the project.

Now, we need to start building the application

Your folder structure should look like this at this point:

- pages
- public
- styles

Now start by adding a jsconfig.json file to the project. This will help you configure absolute imports in your project.

{
    "compilerOptions": {
        "baseUrl": "./"
    }
}

Now create theme directory and add a index.js file in it. This file will be responsible for setting the material-ui theme. Add the following code to the file:

import { createTheme } from "@mui/material";
const theme = createTheme({
    typography: {
        fontFamily: "Montserrat, sans-serif",
    },
    palette: {
        primary: {
            main: "#07617D",
            dark: "#07617D",
        },
    },
});

export default theme;

After this, we will be adding redux to our application for state management.

Adding redux for state management

Create a directory named redux in your project. Then create files named configureStore.js,rootReducer.js, rootSaga.js and a directory named events, inside events add the files named events.helpers.js, events.saga.js and eventsSlice.js.
Let's add code to the files:

`eventsSlice.js`;

import { createSlice } from "@reduxjs/toolkit";

const initialState = {
    event: {},
    events: [],
};

export const eventsSlice = createSlice({
    name: "events",
    initialState,
    reducers: {
        setEventData(state, action) {
            state.event = action.payload;
        },
        fetchEventsStart() {},
        setEvents(state, action) {
            state.events = action.payload;
        },
    },
});

// Action creators are generated for each case reducer function
export const { setEventData, setEvents, fetchEventsStart, setSchedules } =
    eventsSlice.actions;

export default eventsSlice.reducer;

events.helper.js

export const handleFetchEvents = () => {
    return new Promise((resolve, reject) => {
        fetch("/api/events")
            .then((res) => res.json())
            .then((json) => {
                return resolve(json);
            })
            .catch((error) => {
                reject(error);
            });
    });
};

events.saga.js

import { all, call, put, takeLatest } from "redux-saga/effects";
import { handleFetchEvents } from "./events.helpers";
import { fetchEventsStart, setEvents } from "./eventsSlice";

export function* fetchEvents({ payload }) {
    try {
        const events = yield handleFetchEvents();
        yield put(setEvents(events));
    } catch (error) {
        console.log(error);
    }
}
export function* onFetchEventsStart() {
    yield takeLatest(fetchEventsStart.type, fetchEvents);
}
export default function* eventsSagas() {
    yield all([call(onFetchEventsStart)]);
}

rootSaga.js

import { all, call } from "redux-saga/effects";
import eventsSagas from "./events/events.saga";

export default function* rootSaga() {
    yield all([call(eventsSagas)]);
}

rootReducer.js

import { combineReducers } from "@reduxjs/toolkit";
import storage from "redux-persist/lib/storage";
import { persistReducer } from "redux-persist";
import eventsSlice from "./events/eventsSlice";

export const rootReducer = combineReducers({
    eventsData: eventsSlice,
});

const configStorage = {
    key: "root",
    storage,
    whitelist: ["events"],
};

export default persistReducer(configStorage, rootReducer);

configureStore.js

import logger from "redux-logger";
import createSagaMiddle from "redux-saga";
import {
    persistStore,
    FLUSH,
    REHYDRATE,
    PAUSE,
    PERSIST,
    PURGE,
    REGISTER,
} from "redux-persist";
import rootReducer from "./rootReducer";
import { configureStore } from "@reduxjs/toolkit";
import rootSaga from "./rootSaga";

const sagaMiddleware = createSagaMiddle();

export const store = configureStore({
    reducer: rootReducer,
    middleware:
        process.env.NODE_ENV !== "production"
            ? (getDefaultMiddleware) =>
                    getDefaultMiddleware({
                        serializableCheck: false,
                    })
                        .concat(logger)
                        .concat(sagaMiddleware)
            : (getDefaultMiddleware) =>
                    getDefaultMiddleware({
                        serializableCheck: {
                            ignoredActions: [
                                FLUSH,
                                REHYDRATE,
                                PAUSE,
                                PERSIST,
                                PURGE,
                                REGISTER,
                            ],
                        },
                    }).concat(sagaMiddleware),
    devTools: process.env.NODE_ENV !== "production",
});

export const persistor = persistStore(store);
sagaMiddleware.run(rootSaga);

export default {
    store,
    persistor,
};

Here we have successfully completed the redux setup.

Now we need to add the redux store and theme to the application. To do so, we will be editing the _app.js file inside pages directory.
Replace the existing code with the following code:

import { Provider } from "react-redux";
import { persistor, store } from "redux/configureStore";
import { PersistGate } from "redux-persist/integration/react";
import "styles/globals.css";
import { CssBaseline, ThemeProvider } from "@mui/material";
import theme from "theme";

function MyApp({ Component, pageProps }) {
    return (
        <Provider store={store}>
            <PersistGate persistor={persistor}>
                <ThemeProvider theme={theme}>
                    <CssBaseline />
                    <Component {...pageProps} />
                </ThemeProvider>
            </PersistGate>
        </Provider>
    );
}

export default MyApp;

Creating the backend APIs

now we will create a directory named backend. This will have all the backend code required to connect to the mongodb database.
Inside backend directory, create two directories named controllers and models. Inside models we are going to create a file eventModel.js, this will be the schema file for events.
Add the following code to the eventmodel.js file:

const mongoose = require("mongoose");

const Schema = mongoose.Schema;
mongoose.Promise = global.Promise;
const eventSchema = new Schema(
    {
        title: {
            type: String,
            required: true,
        },
        start: {
            type: Date,
            required: true,
        },
        end: {
            type: Date,
            required: true,
        },
        description: String,
        timezone: String,
        start_date: String,
        end_date: String,
        start_time: String,
        end_time: String,
        background: String,
    },
    { timestamps: true, _id: true },
);

module.exports = mongoose.models.Event || mongoose.model("Event", eventSchema);

now inside controllers directory add a file named eventController.js and add the following code

import Event from "../models/eventModel";
import mongoose from "mongoose";

// get all Events
const getEvents = async (req, res) => {
    const events = await Event.find({}).sort({ createdAt: -1 });

    res.status(200).json(events);
};

// get a single Event
const getEvent = async (req, res) => {
    const {
        query: { id },
    } = req;

    if (!mongoose.Types.ObjectId.isValid(id)) {
        return res.status(404).json({ error: "No such Event" });
    }

    const event = await Event.findById(id);

    if (!event) {
        return res.status(404).json({ error: "No such Event" });
    }

    res.status(200).json(event);
};

// create a new Event
const createEvent = async (req, res) => {
    const { title } = req.body;

    let emptyFields = [];

    if (!title) {
        emptyFields.push("title");
    }
    if (emptyFields.length > 0) {
        return res
            .status(400)
            .json({ error: "Please fill in all fields", emptyFields });
    }

    // add to the database
    try {
        const event = await Event.create({
            ...req.body,
        });
        res.status(200).json({ result: event, status: "success" });
    } catch (error) {
        res.status(400).json({ error: error.message });
    }
};

// delete a Event
const deleteEvent = async (req, res) => {
    const { id } = req.body;

    // console.log({ body: req.body, id: req.body.id });
    if (!mongoose.Types.ObjectId.isValid(id)) {
        return res.status(400).json({
            error: "Something is wrong",
        });
    }

    const event = await Event.findOneAndDelete({ _id: id });

    if (!event) {
        return res.status(400).json({ error: "No such Event" });
    }

    res.status(200).json(event);
};

// update a Event
const updateEvent = async (req, res) => {
    const { id } = req.query;

    if (!mongoose.Types.ObjectId.isValid(id)) {
        return res.status(400).json({ error: "No such Event" });
    }

    const event = await Event.findOneAndUpdate(
        { _id: id },
        {
            ...req.body,
        },
    );

    if (!event) {
        return res.status(400).json({ error: "No such Event" });
    }

    res.status(200).json(event);
};

module.exports = {
    getEvents,
    getEvent,
    createEvent,
    deleteEvent,
    updateEvent,
};

now that we have completed the required files we need to create a utility file that will help in setting up the connection with mongodb.
Now create a directory named utils and add a file named mongoDbConnect.js to it. Add the following code to this file:

import mongoose from "mongoose";

const MONGODB_URI = process.env.MONGODB_URI;

if (!MONGODB_URI) {
    throw new Error(
        "Please define the MONGODB_URI environment variable inside .env.local",
    );
}

let cached = global.mongoose;

if (!cached) {
    cached = global.mongoose = { conn: null, promise: null };
}

async function dbConnect() {
    if (cached.conn) {
        return cached.conn;
    }

    if (!cached.promise) {
        const opts = {
            bufferCommands: false,
        };

        cached.promise = mongoose
            .connect(MONGODB_URI, opts)
            .then((mongoose) => {
                return mongoose;
            });
    }

    try {
        cached.conn = await cached.promise;
    } catch (e) {
        cached.promise = null;
        throw e;
    }

    return cached.conn;
}

export default dbConnect;

• The only requirement here is the MONGODB_URI, you can get this from mongodb_atlas dashboard. This is the connection string to connect to mongodb Atlas.

Now we will be creating the api for fetching the data.
For this we'll have to create events directory inside pages/api directory. inside events create index.js and the following code:

import dbConnect from "utils/mongoDbConnect";
import {
    getEvents,
    createEvent,
    deleteEvent,
} from "backend/controllers/eventController";

export default async function handler(req, res) {
    const { method } = req;

    await dbConnect();

    switch (method) {
        case "GET":
            await getEvents(req, res);
            break;
        case "POST":
            await createEvent(req, res);
            break;
        case "DELETE":
            await deleteEvent(req, res);
            break;
        default:
            res.status(400).json({ success: false });
            break;
    }
}

that's it our backend is ready
you can try this integration here https://localhost:3000/api/events

it will show an empty array in response.

now, let's build the frontend

Building the calendar

Let's create a folder named components and then inside components create a Buttons folder and a Dialog folder.
Inside Buttons create PrimayButton.js file and add the following code:

import { Button, styled } from "@mui/material";
import React from "react";

const StyledButton = styled(Button)(({ theme, ...props }) => ({
  textTransform: "initial",
  textTransform: "inherit",
  borderColor: "white",
  borderRadius: "50px",
  color: "white",
  paddingRight: "24px",
  paddingLeft: "24px",
  height: "48px",
  background: " #07617D",

  "&:hover": {
    background: " #07617D",
  },
}));

const PrimaryButton = ({ children, ...props }) => {
  return (
    <StyledButton
      variant="contained"
      sx={{
        ...props.sx,
      }}
      {...props}
    >
      {children}
    </StyledButton>
  );
};

export default PrimaryButton;

Inside Dialog folder create index.js file and add the following code

import { Dialog, DialogContent, DialogTitle, IconButton } from "@mui/material";
import React from "react";
import { MdClose } from "react-icons/md";
const BaseDialog = ({ open, handleClose, children, title }) => {
    return (
        <Dialog open={open} onClose={handleClose} sx={{}} scroll="paper">
            <IconButton
                onClick={() => handleClose()}
                sx={{ position: "absolute", top: "10px", right: "10px" }}
            >
                <MdClose />
            </IconButton>
            {title && <DialogTitle>{title}</DialogTitle>}
            <DialogContent>{children}</DialogContent>
        </Dialog>
    );
};

export default BaseDialog;

Now inside components folder create a folder CustomCalendar, Create three files named: index.js,CreateEventPopup.js and DeleteEventPopup.js and add the following code to the files

index.js

import React, { useState } from "react";
import { Calendar, dateFnsLocalizer } from "react-big-calendar";
import format from "date-fns/format";
import parse from "date-fns/parse";
import startOfWeek from "date-fns/startOfWeek";
import getDay from "date-fns/getDay";
import enUS from "date-fns/locale/en-US";
import "react-big-calendar/lib/css/react-big-calendar.css";
import withDragAndDrop from "react-big-calendar/lib/addons/dragAndDrop";
import { useDispatch, useSelector } from "react-redux";
import CreateEventPopUp from "./CreateEventPopup";
import { setEventData } from "redux/events/eventsSlice";
import DeleteEventPopup from "./DeleteEventPopup";
const DragAndDropCalendar = withDragAndDrop(Calendar);

const locales = {
  "en-US": enUS,
};

let currentDate = new Date();
let currentDay = currentDate.getDay();

const localizer = dateFnsLocalizer({
  format,
  parse,
  startOfWeek: () => startOfWeek(currentDate, { weekStartsOn: currentDay }),
  getDay,
  locales,
});

const customDayPropGetter = (date) => {
  const currentDate = new Date();
  if (date < currentDate)
    return {
      className: "disabled-day",
      style: {
        cursor: "not-allowed",
        background: "rgba(184, 184, 184, 0.1)",
      },
    };
  else return {};
};

const CustomCalendar = ({ events = [], height, style, ...calendarProps }) => {
  const calendarRef = React.createRef();
  const dispatch = useDispatch();
  const [openDialog, setOpenDialog] = useState(false);
  const [openRemoveDialog, setOpenRemoveDialog] = useState(false);
  const [data, setData] = useState({});

  const setEventCellStyling = (event) => {
    if (event.background) {
      let style = {
        background: "rgba(7, 97, 125, 0.1)",
        border: `1px solid ${event.background}`,
        color: "#07617D",
        borderLeft: `3px solid ${event.background}`,

        fontWeight: 600,
        fontSize: "11px",
      };
      return { style };
    }
    let style = {
      background: "rgba(7, 97, 125, 0.1)",
      border: `1px solid #07617D`,
      color: "#07617D",
      borderLeft: "3px solid #07617D",

      fontWeight: 600,
      fontSize: "11px",
    };
    return { style };
  };

  const formats = {
    weekdayFormat: "EEE",
    timeGutterFormat: "hh a",
  };

  const handleSelect = ({ start, end }) => {
    const currentDate = new Date();
    if (start < currentDate) {
      return null;
    }
    if (start > end) return;

    handleOpenPopup();
    dispatch(setEventData({ start, end }));
  };
  const handleOpenPopup = () => {
    setOpenDialog(true);
  };
  const handleEventSelect = (event) => {
    handleRemoveDialogOpen();
    setData(event);
  };
  const handleRemoveDialogOpen = () => {
    setOpenRemoveDialog(true);
  };
  const handleRemoveDialogClose = () => {
    setOpenRemoveDialog(false);
    setEventData({});
  };
  const handleDialogClose = () => {
    setOpenDialog(false);
    dispatch(setEventData({}));
  };

  return (
    <>
      <DragAndDropCalendar
        ref={calendarRef}
        localizer={localizer}
        formats={formats}
        popup={true}
        events={events}
        selectable
        resizable
        longPressThreshold={1}
        eventPropGetter={setEventCellStyling}
        dayPropGetter={customDayPropGetter}
        onSelectSlot={handleSelect}
        onSelectEvent={handleEventSelect}
        views={{ week: true }}
        step={30}
        drilldownView={"week"}
        scrollToTime={currentDate.getHours()}
        defaultView={"week"}
        style={{ height: height ? height : "68vh", ...style }}
        {...calendarProps}
      />

      <CreateEventPopUp open={openDialog} handleClose={handleDialogClose} />
      <DeleteEventPopup
        open={openRemoveDialog}
        handleClose={handleRemoveDialogClose}
        event={data}
      />
    </>
  );
};

export default CustomCalendar;

CreateEventPopup.js

import React from "react";
import {
  Container,
  Dialog,
  DialogTitle,
  TextField,
  Typography,
} from "@mui/material";
import { useState } from "react";
import PrimaryButton from "components/Common/Buttons/PrimaryButton";
import { useDispatch, useSelector } from "react-redux";
import { format } from "date-fns";
import { fetchEventsStart } from "redux/events/eventsSlice";
import BaseDialog from "components/Common/Dialog";

const mapState = ({ eventsData }) => ({
  event: eventsData.event,
});

const CreateEventPopUp = ({ handleClose, open }) => {
  const { event } = useSelector(mapState);
  const startTimeAndDate = event.start;
  const endTimeAndDate = event.end;
  const from_time = startTimeAndDate && format(startTimeAndDate, "hh:mma");
  const formattedStartDate =
    startTimeAndDate && format(startTimeAndDate, "eeee, MMMM dd, yyyy ");
  const to_time = endTimeAndDate && format(endTimeAndDate, "hh:mma");
  const [title, setTitle] = useState("");
  const [backgroundColor, setBackgroundColor] = useState("#000000");
  const dispatch = useDispatch();

  const handleCreateEvent = (e) => {
    e.preventDefault();

    try {
      const schema = {
        title: title,
        description: "",
        background: backgroundColor,
        start: startTimeAndDate,
        end: endTimeAndDate,
      };
      const url = "/api/events";
      fetch(url, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify(schema),
      })
        .then((res) => res.json())
        .then((json) => {
          dispatch(fetchEventsStart({ url: "/api/events" }));
          setTitle("");
        });
    } catch (error) {
      console.log(error);
    }
    handleClose();
  };

  return (
    <BaseDialog open={open} handleClose={handleClose} scroll={`body`}>
      <DialogTitle
        style={{
          fontSize: "21px",
          fontWeight: "bold",
          marginTop: "-24px",
        }}
      >
        Add Event
      </DialogTitle>

      <Container
        sx={{
          background: "white",
          top: "30%",
          left: "10%",
          minWidth: "450px",
          paddingBottom: "64px",
        }}
      >
        {formattedStartDate && (
          <Typography sx={{ fontSize: "18px", fontWeight: "500" }}>
            {formattedStartDate}, {from_time} - {to_time}
          </Typography>
        )}
        <TextField
          fullWidth
          sx={{ marginTop: "16px" }}
          placeholder="Title"
          label="Title"
          value={title}
          onChange={(e) => setTitle(e.target.value)}
        />
        <div>
          <div style={{ paddingTop: "16px" }}>
            <label style={{ fontWeight: 700 }}>Select Color</label>
            <div style={{ display: "flex" }}>
              {colorsList.map((item) => {
                return (
                  <div
                    key={item}
                    style={{
                      width: "20px",
                      height: "20px",
                      background: item,
                      marginRight: "8px",
                    }}
                    onClick={() => setBackgroundColor(item)}
                  ></div>
                );
              })}
            </div>

            <input
              type={"color"}
              value={backgroundColor}
              onChange={(e) => setBackgroundColor(e.target.value)}
              style={{
                width: "100%",
                marginTop: "4px",
                border: "none",
                background: "none",
              }}
            />
            <Typography>
              Selected color: <b>{backgroundColor}</b>
            </Typography>
          </div>
        </div>

        <div
          style={{
            display: "flex",
            padding: "8px",
            justifyContent: "center",
            paddingTop: "32px",
          }}
        >
          <PrimaryButton
            onClick={handleCreateEvent}
            sx={{
              paddingRight: "32px",
              paddingLeft: "32px",
            }}
          >
            Confirm
          </PrimaryButton>
        </div>
      </Container>
    </BaseDialog>
  );
};

export default CreateEventPopUp;

const colorsList = [
  "#624b4b",
  "#bc2020",
  "#bc20b6",
  " #420b40",
  "#1fad96",
  "#3538ed",
  " #1c474a",
  "#32bb30",
  "#cae958",
  "#dc3e09",
];

DeleteEventPopup.js

import React from "react";
import { useDispatch } from "react-redux";
import { useSelector } from "react-redux";
import { FormControlLabel, Radio, Typography } from "@mui/material";
import BaseDialog from "components/Common/Dialog";
import { fetchEventsStart } from "redux/events/eventsSlice";
import PrimaryButton from "components/Common/Buttons/PrimaryButton";

const DeleteEventPopup = ({ event, open, handleClose }) => {
  const dispatch = useDispatch();

  const handleRemoveEvent = () => {
    const data = {
      id: event._id,
    };
    fetch("/api/events", {
      method: "DELETE",
      headers: {
        "Content-Type": "application/json",
      },

      body: JSON.stringify(data),
    })
      .then((res) => res.json())
      .then((json) => {
        handleClose();

        dispatch(fetchEventsStart());
      });
  };

  return (
    <BaseDialog open={open} handleClose={handleClose}>
      <div
        style={{
          display: "flex",
          justifyContent: "center",
          maxWidth: "480px",
          flexDirection: "column",
          paddingLeft: "8px",
          paddingRight: "8px",
          marginTop: "16px",
        }}
      >
        <Typography fontSize={`20px`} fontWeight={`700`} paddingBottom="16px">
          Do you really want to delete this event?
        </Typography>

        <div
          style={{
            justifyContent: "center",
            display: "flex",
          }}
        >
          <PrimaryButton title={`Confirm`} onClick={handleRemoveEvent}>
            Confirm
          </PrimaryButton>
        </div>
      </div>
    </BaseDialog>
  );
};

export default DeleteEventPopup;

Now that we have created the calendar, it's time for us to add the calendar to the pages/index.js by replacing all the existing code with the following code:

import CustomCalendar from "components/CustomCalendar";
import Head from "next/head";
import { useEffect } from "react";
import { useDispatch, useSelector } from "react-redux";
import { fetchEventsStart } from "redux/events/eventsSlice";

const mapState = ({ eventsData }) => ({
  events: eventsData.events,
});
export default function Home() {
  const dispatch = useDispatch();
  const { events } = useSelector(mapState);

  const getAllEvents = () => {
    // fetch()
    dispatch(fetchEventsStart());
  };
  useEffect(() => {
    getAllEvents();
  }, []);
  const calendarEvents = events.map((item) => {
    const { start, end } = item;
    return {
      ...item,
      start: new Date(start),
      end: new Date(end),
    };
  });
  return (
    <div>
      <Head>
        <title>Calendar App</title>
        <meta name="description" content="Generated by create next app" />
        <link rel="icon" href="/favicon.ico" />
      </Head>
      <CustomCalendar height={"100vh"} events={calendarEvents} />
    </div>
  );
}

That's it the frontend is now ready. you can add or delete the events.

Congratulations! you have successfully created your calendar application.

here is the code and demo of what we just built, you can clone the project and test it

• Github Repository: https://github.com/himohitmehta/calendar-app-tutorial
• Demo : https://calendar-app.mohitmehta.dev/

In the coming days I'll also add authentication and the ability to update the events in the calendar.

I hope this is helpful for everyone 😊.