How to create an array of all objects from many models in rails

Question

I am working in rails 2.. I have a doubt.

In my application , i have 3 models like

Blog, Wiki , Media

I am trying to create an array like @final with all the blogs , wikis, medias posted under my application .

I have tried with

@blogs = Blog.all
@wikis = Wiki.all
@medias = Media.all

@final = []
@final << @blogs << @wikis << @medias

The above final array has 3 arrays in it..

But i am expecting to keep final array with the objects returned from 3 models

How to do so ?? PLease give suggestions

EDIT

I thing i tried is

 @final = []
 @blogs = Blog.all
 @wikis = Wiki.all
 @medias = Media.all
 @final = @blogs + @wikis + @medias

This is performing exactly what i need .. But its just listing all the blogs , medias and wikis. How to list all the entities based on the creation date of the particular object

please explain more what means: "to keep only one array with the objects returned from 3 models" — Anatoly
– Anatoly, Commented Jul 20, 2011 at 8:22
I think your sorting problem should go into another question. (Otherwise try with order('created_on')...) — powerMicha
– powerMicha, Commented Jul 20, 2011 at 8:40

Community · Accepted Answer · 2017-05-23 12:26:51Z

5

You're using the wrong operator, you want this:

@final = @blogs + @wikis + @medias

The << operator for an Array:

Pushes the given object on to the end of this array.

whereas the + operator:

Returns a new array built by concatenating the two arrays together to produce a third array.

You could also use flatten if you were really attached to << for some reason:

@final = (@final << @blogs << @wikis << @medias).flatten

but that would be a bit pointless. As noted by powerMicha, you need to start the << chain off with @final (or some temporary array) if you don't want to modify any of the @blogs, @wikis, or @medias arrays.

As far as sorting them goes, you could use sort_by!:

@final.sort_by(&:created_at)

That assumes that you have the usual created_at method on the objects.

edited May 23, 2017 at 12:26

CommunityBot

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answered Jul 20, 2011 at 8:23

mu is too short

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6 Comments

useranon Over a year ago

@mu is too short -- Hi i tried with + operator it worked . But how to list them based on the creation date of each object

mu is too short Over a year ago

@Jasmine: Sorry, I missed that part of your question. I've added an update to cover it.

powerMicha Over a year ago

What is the content of @blogs after final = (@blogs << @wikis << @medias).flatten? I think, this statement will lead to @blogs = [ blog1, blog2, ..., [ wiki1, wiki2, ... [ media1, media2, ... ]]]

mu is too short Over a year ago

@powerMicha: Yes, that will modify @blogs but @final will be right, I'll add an update to sort that out. Thanks.

useranon Over a year ago

@mu is too short -- How to apply the limit in the final array ??

|

mu is too short · Accepted Answer · 2011-07-20 08:29:48Z

2

Try Array.flatten.

Returns a new array that is a one-dimensional flattening of this array (recursively).

edited Jul 20, 2011 at 8:29

mu is too short

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answered Jul 20, 2011 at 8:24

auralbee

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Comments

powerMicha · Accepted Answer · 2011-07-20 08:32:22Z

2

With << you are putting your arrays into an array. This is the same like:

@final = [@blogs, @wikis, @medias]

I suggest mu is too short's answer to join your arrays

@final = @blogs + @wikis + @medias

See API

answered Jul 20, 2011 at 8:32

powerMicha

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