extra.txt

//Insertion using an Instance
const student1 = new Student({name: 'Swapnil', roll: 1, gender: 'Male', std: 'XII'});
student1.save()
    .then(data => {
        console.log("One Student Data added successfully.");
        console.log(data);
    })
    .catch(err => {
        console.log("Error occured during insertion.");
        console.log(err);
    })


//Insertion using a Model method
Student.insertMany([
    {
        name: 'Chokshi',
        roll: 2,
        gender: 'Male'
    },
    {
        name: 'Shyam',
        roll: 3,
        gender: 'Female'
    },
    {
        name: 'Krishna',
        roll: 4,
        gender: 'Female',
        std: 'X'   
}])
    .then(data => {
        console.log("Multiple Student Data added successfully");
        console.log(data);
    })
    .catch(err => {
        console.log("Error occured during multiple insertions.");
        console.log(err);
    })


//Deletion
Student.deleteOne({name: 'Chokshi'})
    .then(msg => {
        console.log("One item deleted successfully.");
        console.log(msg);
    })
    .catch(err => {
        console.log("Error occured during deletion.");
        console.log(err);
    })

Student.deleteMany({gender: 'Male'})
    .then(msg => {
        console.log("Multiple items deleted successfully.");
        console.log(msg);
    })
    .catch(err => {
        console.log("Error occured during deletions.");
        console.log(err);
    })


//Updation
Student.updateOne({name: 'Shyam'}, {gender: 'Male'})
    .then(msg => {
        console.log("One item updated successfully.");
        console.log(msg);
    })
    .catch(err => {
        console.log("Error occured during updation.");
        console.log(err);
    })

Student.updateMany({name: {$in: ['Swapnil','Shyam']}}, {std: 'IX'})
    .then(msg => {
        console.log("Multiple items updated successfully.");
        console.log(msg);
    })
    .catch(err => {
        console.log("Error occured during updations.");
        console.log(err);
    })


//Finding
Student.find({roll: 3})
    .then(data => console.log(data))
    .catch(err => {
        console.log("Data not found.");
        console.log(err);
    })

Student.findOne({std: 'XII'})
    .then(data => console.log(data))
    .catch(err => {
        console.log("Data not found.");
        console.log(err);
    })


Student.findOneAndUpdate({name: 'Krishna'}, {std: 'V'}, {new: true})
    .then(data => console.log(data))

Student.findOneAndDelete({roll: 'X'})
    .then(msg => console.log(msg))



//Methods
const findData = async () => {
    const foundData = await Student.find({name: 'Swapnil'});
    console.log(foundData);
}
findData();

const removeAll = async() => {
    const msg = await Student.deleteMany({});
    console.log(msg);
}
removeAll();



//Instance Methods
Student.insertMany({name: 'Jimmy', roll: 6, gender: 'Other'});

dataSchema.methods.addStd = function () {
    this.std = 'V';
    return this.save();
}

const findData = async () => {
    const foundData = await Student.findOne({name: 'Jimmy'});
    console.log(foundData);

    foundData.addStd((data, err) => {
        console.log(data);
    })
}

findData();


//Static method
dataSchema.statics.cleanRoll = function () {
    return this.updateMany({}, {roll: 0});
};

Student.cleanRoll().then(res => console.log(res))