Expressions

Expressions are the main bread and butter of CookieDB. At the most basic level, expressions are a tiny programming language built into CookieDB that takes in some input and results in some output.

Let's look at a small example:

eq($name, "CookieFan37")

Let's look at a more complex example:

and(starts_with($name, "Cookie"), gt($age, 10), not(eq($description, null)))

Let's break down this syntax.

All expressions are run against a document of some sort. If we want our expression to result in a value based on the document (which we most likely do), we can use the "$" syntax to insert the value of that key into the expression. Let's take the following document as an example and see what we can use the $ syntax for:

{
  "name": "CookieFan37",
  "favorite": {
    "color": "blue",
    "number": 3
  }
}

The following $ syntax is valid:

  • $name -> "CookieFan37"
  • $favorite.color -> "blue"
  • $favorite.number -> 3

The following syntax is invalid:

  • $blue - There is no key by the name blue
  • $favorite - There is a key by the name favorite, but it's an object and not a literal value

Inside expressions, we can also define constant literals. These can be the following:

  • numbers (i.e. 10, -23, 3.213)
  • strings (i.e. "CookieFan37", 'CookieHater')
  • booleans (i.e. true, false)
  • null (i.e. null)

The last part of the syntax are the functions. Functions follow the syntax of some_name(some_input, maybe_another_input). There are a lot of functions:

  • and
    • Takes in any number of inputs and does logical and on them
    • ex: and(true, true, true)
  • or
    • Takes in any number of inputs and does logical or on them
    • ex: or(false, true, true)
  • starts_with
    • Returns true if a string starts with another string. Returns false if it does not.
    • ex: starts_with('cookie', 'co')
  • ends_with
    • Returns true if a string ends with another string. Returns false if it does not.
    • ex: ends_with('cookie', 'ie')
  • to_lower
    • Takes one input string and makes it lowercase
    • ex: eq(to_lower('cOOKIE'), 'cookie')
  • to_upper
    • Takes one input string and makes it uppercase
    • ex: eq(to_upper('Cookie'), 'COOKIE')
  • gt
    • Takes two numbers and checks if the left is greater than the right
    • ex: gt(10, 5)
  • lt
    • Takes two numbers and checks if the left is less than the right
    • ex: lt(5,10)
  • eq
    • Takes two values of any types and checks if they are equal
    • eq(true, true)
  • gt_or_eq
    • Takes two numbers and checks if the left is greater than or equal to the right
    • ex: gt_or_eq(12, 11)
  • lt_or_eq
    • Takes two numbers and checks if the left is less than or equal to the right
    • ex: lt_or_eq(11, 12)
  • subtract
    • Takes two numbers and subtracts the right from the left
    • ex: eq(subtract(10, 5), 5)
  • divide
    • Takes two numbers and divides the right from the left. If the right is zero, this will return null
    • ex: eq(divide(10, 5), 2)
  • add
    • Takes any amount of numbers and adds them together. It also works as a concat function for strings.
    • ex: eq(add(1, 2, 3), 6)
  • multiply
    • Takes any amount of numbers and multiplies them together
    • ex: eq(multiply(1, 2, 3), 6)
  • current_time
    • Returns the current time in Unix milliseconds
    • ex: eq(current_time(), 1668304518135)*
  • to_date_string
    • Takes in unix milliseconds and returns a string representation
    • ex: eq(to_date_string(1668304518135), 'Sun, 13 Nov 2022 01:55:18 GMT')
  • year
    • Takes in unix milliseconds and returns the UTC year
    • ex: eq(year(1668304518135), 2022)
  • month
    • Takes in unix milliseconds and returns the UTC month (0-11)
    • ex: eq(month(1668304518135), 10)
  • hour
    • Takes in unix milliseconds and returns the UTC hour (0-23)
    • ex: eq(hour(1668304518135), 1)
  • minute
    • Takes in unix milliseconds and returns the UTC minute (0-59)
    • ex: eq(minute(1668304518135), 55)
  • second
    • Takes in unix milliseconds and returns the UTC minute (0-59)
    • ex: eq(second(1668304518135), 18)
  • day_of_week
    • Takes in unix milliseconds and returns the UTC day of week (0-6)
    • ex: eq(day_of_week(1668304518135), 0)
  • day_of_month
    • Takes in unix milliseconds and returns the UTC day of month (1-31)
    • ex: eq(day_of_month(1668304518135), 13)
  • if_else
    • Takes in a boolean expression, and two results. If the boolean expression is true, it will take the first child, otherwise it will take the second child
    • ex: if_else(true, true, false)
  • not
    • Takes in one value, it will return false if given a truthy value, else it will return true
    • ex: not(false)
  • in_range
    • Takes in an input number, a minimum, and a maximum number. It will return true if the input is in the range, otherwise it will return false.
    • ex: in_range(5, 0, 10)
  • coalesce
    • Takes in any number of inputs and returns the first non-null one
    • ex: coalesce(null, true, 'hi')
  • abs
    • Takes in a number and returns the absolute value
    • ex: eq(abs(-5), 5)
  • asin
    • Takes in a number and returns the arcsine
    • ex: eq(asin(0), 0)
  • acos
    • Takes in a number and returns the arccosine
    • ex: eq(acos(1), 0)
  • atan
    • Takes in a number and returns the arctangent
    • ex: eq(atan(0), 0)
  • atan2
    • Takes in a number and returns the arctan2 (NOTE: the arguments are y, x and not x, y)
    • ex: eq(atan(1, 1), divide(pi(), 4))*
  • average
    • Takes in any number of numeric children and returns the average
    • ex: eq(average(0, 5, 10), 5)
  • ceil
    • Takes in a numeric value and returns the ceiling
    • ex: eq(ceil(5.1), 6)
  • floor
    • Takes in a numeric value and returns the floor
    • ex: eq(floor(5.1), 5)
  • round
    • Takes in a numeric value and returns the value rounded
    • ex: eq(round(5.1), 5)
  • sin
    • Takes in an angle in radians and returns the sine
    • ex: eq(sin(0), 0)
  • cos
    • Takes in an angle in radians and returns the cosine
    • ex: eq(cos(0), 1)
  • tan
    • Takes in an angle in radians and returns the tangent
    • ex: eq(tan(0), 0)
  • sec
    • Takes in an angle in radians and returns the secant, returns null instead of throwing
    • ex: eq(sec(0), 1)
  • csc
    • Takes in an angle in radians and returns the cosecant, returns null instead of throwing
    • ex: eq(csc(0), null)
  • cot
    • Takes in an angle in radians and returns the cotangent, returns null instead of throwing
    • ex: eq(cot(0), null)
  • degrees
    • Takes in an angle in radians and returns the degrees
    • ex: eq(degrees(pi()), 180) radians
    • Takes in an angle in radians and returns the degrees
    • ex: eq(radians(180), pi())
  • exp
    • Takes in some value and returns e to the power of that value
    • ex: eq(exp(0),1)
  • power
    • Takes in value for base and exponent and computes the power
    • ex: eq(power(2, 4), power(4, 2))
  • log
    • Takes in a value for input and base and computes the logarithm
    • ex: eq(log(256, 2), 8)
  • max
    • Takes in any amount of elements and returns the maximum value
    • ex: eq(max(1, 5, -40, 1000), 1000)
  • min
    • Takes in any amount of elements and returns the minimum value
    • ex: eq(min(1, 5, -40, 1000), -40)
  • pi
    • Returns the value of pi
    • ex: eq(pi(), 3.141592653589793)
  • random
    • Returns a random value from 0 to 1
    • ex: eq(random(), 0.42637976796743104)*
  • sign
    • Returns the sign of the number. If positive 1, if negative -1, otherwise 0
    • ex: eq(sign(-3), -1)
  • sqrt
    • Takes in a number and returns the square root
    • ex: eq(sqrt(4), 2)

If you've looked through the whole list and can't find something that matches your usecase, please let us know by opening an issue on the github!

* May not work as described due to technicalities

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