How to get struct in array

shahryarjb

Hello, how do I get struct in array ? please see my pic :

I need to get the struct’s params , like this : a.cms_post.title

My output is :

[
  %TrangellCmsService.Cms.Db.Post{
    __meta__: #Ecto.Schema.Metadata<:loaded, "cms_post">,
    changelog: true,
    changelog_category: "/ss/ppos",
    cms_post_category: #Ecto.Association.NotLoaded<association :cms_post_category is not loaded>,
    cms_post_category_id: "960c30f2-183e-4430-a96d-4f0fd41fe37b",
    description: "test test test test test test tetststststss tskkkstest of test fo test of test more test more test for test for test tes",
    discourse: true,
    discourse_link: "/ss/ppos",
    download_ext_link: "/ss/ppos", 
    group_acl: "admin",
    id: 6,
    inserted_at: ~N[2018-04-29 11:45:05.311436],
    learn: true,
    learn_category: "/ss/ppos",
    pic_x1_link: "/ss/ppos",
    pic_x2_link: "/ss/ppos",
    pic_x3_link: "/ss/ppos",
    plugin: true,
    plugin_category: "/ss/ppos",
    post_type: "free",
    price: "30000",
    screen_shot: false,
    screen_shot_category: "/ss/ppos",
    seo_alias_link: "7seo-why-seo",
    seo_description: "for the test for test for test for test tete of test",
    seo_language: "fa",
    seo_language_link: "/ss/ppos",
    seo_tag: "test,test,test,test",
    seo_words: "test,test,test,test",
    status: true,
    title: "shahryar",
    updated_at: ~N[2018-04-29 11:45:05.311884]
  }
]

13 comments

#ecto #troubleshooting #struct

0 4023 13

2018-05-03 10:15:05 UTC

Marked As Solved

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Eiji

@shahryarjb: I assumed you want to fetch online titles. If so then easier is to call specific query.

defmodule Example do
  import Ecto.Query

  # aliases for Post and PostCategory here

  def sample(seo_alias_link, group_acl) do
    query =
      from(
        post_category in PostCategory,
        join: post in assoc(post_category, :cms_post)
        order_by: post_category.inserted_at,
        limit: 10,
        preload: [cms_post: post],
        where: p.seo_alias_link == ^seo_alias_link
      )

    if group_acl == "admin" do
      query
    else
      where(
        query,
        [post_category, post],
        post_category.group_acl == ^group_acl and post.group_acl == ^group_acl
      )
    end

    query
    |> Repo.all()
    |> Enum.map(& &1.cms_post)
    |> List.flatten()
    |> Enum.map(& &1.title)
  end
end

Example.sample("jsjsjs", "admin")

Post #11

Also Liked

peerreynders

Something like

Enum.map(a.cms_post, &(Map.get(&1,:title)))

would return a list of title values

Map.get/3
Enum.map/2

a.cms_post
|> hd()
|> Map.get(:title)

returns the title of the post in the head of the list

Kernel.hd/1

def get_title([%TrangellCmsService.Cms.Db.Post{title: title}|_]),
  do: title

i.e. using pattern matching for destructuring rather than dot notation.

Post #3

NobbZ

Not array, it is a linked list, and you can use the usual iteration functions from the Enum module.

You can not directly acces the fields because it’s ambiguous which of the potentially many lists contents you want to access.

Post #1

Eiji

@shahryarjb If I understand you correctly then this code should help you:

categories # here you have root list from your gist
|> Enum.find(& &1.seo_alias_link == "jsjsjs") # here you have list element
|> Map.fetch!(:cms_post) # here you are fetching sub-list from element
|> Enum.map(& &1.title) # finally here you are getting title for all elements

Post #5

Last Post!

Eiji

@shahryarjb: In my previous answer &Example.sample/2 returns query. Calling &Repo.all/1 on such result should return already list of titles, so you do not need to work on lists and structs to fetch them manually. I think that such query-only way is easier.

Post #13