Have nil value on parameter - lua

Question

I am creating a game in which liquid will come out. I am using the particle systems of the physics engine of Corona. For the parameter of particle group, i get it from a method. When i run the program i get an error message saying that the parameter is a nil value.
Code:
-- Will randomly drop water stream at random locations and with random colors
--Delcare class variables
local physics = (require"physics")
physics.start()
local w = display.contentWidth
local h = display.contentHeight
local particleSystem = physics.newParticleSystem({
filename = "particle.png",
colorMixingStrength = 0.1,
radius = 3,
imageRadius = 6
})
--function to start the water stream
local function start()
end
--fucntion to end the water stream
local function stop()
end
--a function to create particle paramerters
-- flag to determine if the particle parameter should have random colors
-- WILL have RANDOM location
local function createParticleParameter(flag, x, y, color)
local param = {
flags = flags,
x = x,
y = y,
color = color,
radius = 10,
linearVelocityX = 0,
linearVelocityY = 10,
lifetime = 10
}
return param
end
local function onTimer()
local parmas = createParticleParameter("water", math.random(0, display.contentWidth), 0, {0, 1, 0})
particleSystem:createGroup(params)
end
timer.performWithDelay( 1000, onTimer, 0 )
The error message:
---------------------------
Corona Runtime Error
---------------------------
attempt to index a nil value
stack traceback:
[C]: in function 'createGroup'
main.lua:47: in function '_listener'
?: in function <?:167>
?: in function <?:221>
I checked if the parameter was right, and it was because when i ran this program it worked for some reason:
-- Will randomly drop water stream at random locations and with random colors
--Delcare class variables
local physics = (require"physics")
physics.start()
local w = display.contentWidth
local h = display.contentHeight
local particleSystem = physics.newParticleSystem({
filename = "particle.png",
colorMixingStrength = 0.1,
radius = 3,
imageRadius = 6
})
--function to start the water stream
local function start()
end
--fucntion to end the water stream
local function stop()
end
--a function to create particle paramerters
-- flag to determine if the particle parameter should have random colors
-- WILL have RANDOM location
local function createParticleParameter(flag, x, y, color)
local param = {
flags = flags,
x = x,
y = y,
color = color,
radius = 10,
linearVelocityX = 0,
linearVelocityY = 10,
lifetime = 10
}
return param
end
local function onTimer()
local parmas = createParticleParameter("water", math.random(0, display.contentWidth), 0, { 0,1,0})
particleSystem:createGroup({
flags = "water",
x = math.random(0, display.contentWidth),
y = 0,
color = {0, 1,0 },
radius = 10,
linearVelocityX = 0,
linearVelocityY = 10,
lifetime = 10
})
end
timer.performWithDelay( 1000, onTimer, 0 )
With the only major difference is that I manually placed the parameters.
Why is this happening?

Answer 1

You spelled params wrong
local parmas = createParticleParameter("water", math.random(0, display.contentWidth), 0, {0, 1, 0})