Data validation rules in Firebase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are Firebase data validation rules?

Firebase data validation rules are conditions set to check if data being written to the database is correct and safe before saving it.

beginner

Why is data validation important in Firebase?

Data validation helps prevent bad or harmful data from entering the database, keeping the app reliable and secure.

intermediate

How do you write a simple Firebase rule to allow only strings for a field called 'name'?

Use the rule: <br> "name": { ".validate": "newData.isString()" } <br> This checks that the new data for 'name' is a string.

beginner

What does newData.exists() check in Firebase rules?

It checks if the new data being written actually exists (is not null or deleted).

intermediate

How can you restrict a number field 'age' to be between 0 and 120 in Firebase rules?

Use: <br> "age": { ".validate": "newData.isNumber() && newData.val() >= 0 && newData.val() <= 120" }

What does Firebase data validation rules do?

A Delete old data from the database

B Automatically fix errors in data

C Check data before saving to ensure it meets conditions

D Encrypt data in the database

Firebase validation rules check if data meets set conditions before saving it.

Which function checks if new data is a string in Firebase rules?

A newData.isBoolean()

B newData.exists()

C newData.isNumber()

D newData.isString()

newData.isString() returns true if the new data is a string.

How do you ensure a field 'score' is a number greater than or equal to zero?

A ".validate": "newData.isNumber() && newData.val() >= 0"

B ".validate": "newData.isString() && newData.val() >= 0"

C ".validate": "newData.exists()"

D ".validate": "newData.isBoolean()"

This rule checks that 'score' is a number and not negative.

What happens if data does not pass Firebase validation rules?

A The data is saved anyway

B The data write is rejected

C The data is saved but marked invalid

D The database crashes

Firebase rejects any data that fails validation rules.

Which of these is NOT a valid Firebase validation function?

A newData.isDate()

B newData.isString()

C newData.isNumber()

D newData.exists()

newData.isDate() is not a valid Firebase validation function.

Explain how Firebase data validation rules help keep your database safe and reliable.

Think about what happens if wrong data is saved.

Describe how to write a Firebase rule that only allows numbers between 1 and 100 for a field called 'rating'.

Use logical AND to combine checks.