How can I merge two arrays? Something like this:
@movie = Movie.first()
@options = Movie.order("RANDOM()").first(3).merge(@movie)
But it doesn't work.
In @options I need an array with four elements includes @movie.
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5 Answers
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2.2.2 :001 > [1,2,3] + [4,5,6]
=> [1, 2, 3, 4, 5, 6]
But you don't have 2 arrays.
You could do something like:
@movie = Movie.first()
@options = Movie.order("RANDOM()").first(3).to_a << @movie
To merge (make the union of) arrays:
[1, 2, 3].union([2, 4, 6]) #=> [1, 2, 3, 4, 6] (FROM RUBY 2.6)
[1, 2, 3] | [2, 4, 6] #=> [1, 2, 3, 4, 6]
To concat arrays:
[1, 2, 3].concat([2, 4, 6]) #=> [1, 2, 3, 2, 4, 6] (FROM RUBY 2.6)
[1, 2, 3] + [2, 4, 6] #=> [1, 2, 3, 2, 4, 6]
To add element to an array:
[1, 2, 3] << 4 #=> [1, 2, 3, 4]
But it seems that you don't have arrays, but active records. You could convert it to array with to_a, but you can also do directly:
Movie.order("RANDOM()").first(3) + [@movie]
which returns the array you want.
answered Dec 26, 2018 at 17:56
Ana María Martínez Gómez
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Comments
There's two parts to this question:
How to "merge two arrays"? Just use the
+method:[1,2,3] + [2,3,4] => [1, 2, 3, 2, 3, 4]How to do what you want? (Which as it turns out, isn't merging two arrays.) Let's first break down that problem:
@movieis an instance of yourMoviemodel, which you can verify with@movie.class.name.@optionsis anArray, which you can verify with@options.class.name.All you need to know now is how to append a new item to an array (i.e., append your
@movieitem to your@optionsarray)You do that using the double shovel:
@options << @moviethis is essentially the same as something like:
[1,2,3] << 4 => [1,2,3,4]
Comments
Well, If you have an element to merge in an array you can use <<:
Eg: array = ["a", "b", "c"], element = "d"
array << element
=> ["a", "b", "c", "d"]
Or if you have two arrays and want duplicates then make use of += or simply + based on your requirements on mutability requirements:
Eg: array_1 = [1, 2], array_2 = [2, 3]
array_1 += array_2
=> [1, 2, 2, 3]
Or if you have two arrays and want to neglect duplicates then make use of |= or simply |:
Eg: array_1 = [1, 2], array_2 = [2, 3]
array_1 |= array_2
=> [1, 2, 3]
Comments
@movie isn't an array in your example, it is just a single instance of a movie. This should solve your problem:
@options << @movie
