Diving into APIs

Code Demonstration Link

• DevTinder Backend Repository

This README serves as a reference for API concepts and operations encountered while developing the DevTinder app. It includes notes on data handling, database interactions, and key differences between JavaScript and JSON objects.

Table of Contents

1. JavaScript Object vs JSON Object
2. Receiving Data Through POST API
3. Retrieving Users from the Database
4. Handling Duplicate Documents with findOne()
5. Delete API - Removing Documents from Database
6. PATCH vs PUT API
7. Updating Data with PATCH API

1. JavaScript Object vs JSON Object

Key Differences

2. Receiving Data Through POST API

Overview

The POST API is used to receive data from the client. In the DevTinder app, this data is often user information that needs to be stored in the database.

Process

• Step 1: Set up a route that handles incoming POST requests.
• Step 2: Extract data from the request body. Ensure data validation and sanitize inputs to prevent issues such as SQL injection or XSS.
• Step 3: Once validated, structure the data appropriately before pushing it into the database.
• Step 4: Handle errors or success responses based on database operations to provide feedback to the client.

app.use(express.json());
//signup api for signing the user
app.post("/signup", async (req, res) => {
    const data = req.body;
    const user = new User(data)

    try {
        await user.save();
        res.send("User added successfully")

    } catch (err) {
        res.status(400).send("Error in saving the user:" + err.message)
    }
})

3. Retrieving Users from the Database

Overview

Fetching users from the database is essential for listing or displaying information on the frontend.

Process

• Step 1: Set up a GET API route that triggers the database query for retrieving users.
• Step 2: Define query filters (if any) based on the request parameters. For example, you may want to fetch users with specific attributes.
• Step 3: Execute the query and structure the results before sending them back in the API response.
• Step 4: Ensure the response format is JSON, allowing the client to process and display data as needed.

// Feed API - get all the users form the database
app.get("/feed", async (req, res) => {

    try {
        const users = await User.find({})
        if (users.length === 0) {
            res.send("No user found")
        } else {
            console.log(users);
            res.send(users)
        }
    }
    catch (err) {
        res.status(400).send("Something went wrong")
    }

})

4. Handling Duplicate Documents with findOne()

Overview

When findOne() is used with duplicate email documents in the database, MongoDB will return the first matching document it finds based on the collection's internal document ordering.

Key Points

• Ordering: MongoDB does not guarantee a specific order unless specified with an index. The document returned will typically be the first found, according to the insertion order.
• Best Practice: To avoid duplicates, enforce uniqueness in fields like email by using unique indexes.

    //user API to find the single user by by email
    app.get("/user", async (req, res) => {
        //getting user from body
        const userEmail = req.body.emailId;
        try {
            const users = await User.findOne({ emailId: userEmail })
            if (users.length === 0) {
                res.status(400).send("User not found")
            } else {

                // console.log(users)
                res.send(users)
            }
        }
        catch (err) {
            res.status(400).send("Something went wrong")
        }
    })

5. Delete API - Removing Documents from Database

Overview

The Delete API is used to remove specific documents from the database, allowing for efficient data management.

Key Method: findByIdAndDelete()

• Accepts the document's _id to identify and delete the target document.
• Returns the deleted document or null if no document is found.
• Usage: Primarily used for deleting user profiles or unwanted data from the collection.

    //delete user API - deleting a user by its id
app.delete("/user", async (req, res) => {
    const userId = req.body.userId;

    try {
        const users = await User.findByIdAndDelete(userId);
        res.send("User deleted Successfully")

    } catch (err) {
        res.status(400).send("Something went wrong")
    }
})

6. PATCH vs PUT API

7. Updating Data with PATCH API

Overview

The PATCH API is used to update specific fields within a document without affecting other data.

Key Method: findByIdAndUpdate()

• Accepts the document's _id and an object with updated data.
• Only the fields in the update object will be modified; others remain unchanged.
• Use Case: Ideal for updating user information like username, bio, or profile picture without affecting other fields.

// patch user API - updating the data of user
app.patch("/user", async (req, res) => {
    const userId = req.body.userId;
    const data = req.body;

    try {
        const user = await User.findByIdAndUpdate({ _id: userId }, data, { returnDocument: "before" });
        console.log(user)
        res.send("User updated successfully")

    } catch (err) {
        res.status(400).send("Something went wrong")
    }
})

This README is part of the DevTinder backend documentation. Expand upon these notes as you dive deeper into API handling and database management.