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Andrés Ucero
Asked: 2021-01-01 08:11:57 +0800 CST 2021-01-01 08:11:57 +0800 CST

Problem with LIMIT in Rails

  • 772

I want to introduce a variable in a query, and this generates an error, can someone explain to me what happens?

Here the code:

    #Ordenamos el arreglo menor, de menor a mayor
    @[email protected]
    #Seleccionamos el menor del arreglo menor
    @[email protected](1)
    #Seleccionamos las muestras de cada periodo, la cantidad de muestras viene dada por el valor de la variable @m
    Item.where("periodo=1 AND año='2017'").limit("#{@m}")
    @prueba=[]
    @consultaPrueba.each do |consulta|
        @prueba.push(consulta.ventClient)
    end

When executing the query I get the following error:

enter image description here

postgresql

1 Answers

  1. Best Answer

    The error tells you that the value of the variable @mis not a number (it limitneeds a number as a parameter), it is [[3]]; you get the value as a consequence of using take(which returns an array) and interpolating its value (which converts it to a String ).

    Consider the following examples:

    @m = [2, 1, 3]
#=> [2, 1, 3]

@m.take(1)
#=> [2]

"#{@m.take(1)}"
#=> "[2]"

    If you want to take the smallest number from an array you can use min:

    @m.min
#=> 1

    Your code would look like this:

    Item.where("periodo=1 AND año='2017'").limit(@m.min)
    • 1