Railsでフォロー機能を作るためのモデルの書き方

This is the presentation I gave at the "First LT Meeting #2" for the students on May 9, 2020.

Transcript

1. RailsͰϑΥϩʔػೳΛ࡞ΔͨΊ
   ͷϞσϧͷॻ͖ํ
   ϑΟϤϧυϒʔτΩϟϯϓ ΦϯϥΠϯLTձ
   ima1zumi
   2020-05-09
   

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2. ࣗݾ঺հ
   - @ima1zumiʢࠓઘ ຑཬʣ
   - Ҏલ͸SIerͰCOBOLͱ͔DB৮ͬͯ·ͨ͠
   - Rails ϢʔβʔϑΥϩʔͷϓϥΫςΟεத
   - ࠷ۙͷझຯɿ͋ͭ৿ɺίʔώʔɺࣗ୐։ൃ؀ڥΛ͍͍ײ͡ʹ͢Δ͜ͱ
   
   

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3. ςʔϚΛબΜͩཧ༝
   - ϢʔβʔϑΥϩʔͰϞσϧʹॻ͘belongs_toͱ͔
   has_many͕ढจʹݟ͑Δ
   - ಡΈํ͕෼͔Βͳͯ͘೰Μͩ
   
   

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4. ͜Ε͔Β࿩͢͜ͱ
   - ϑΥϩʔػೳΛ࡞Δʹ͸ɺσʔλϕʔεΛͲ͏࡞Ε
   ͹͍͍ͷ͔ʢσʔλϕʔεͷ࿩ʣ
   - ͦΕΛRailsͰͲ͏ఆٛ͢Δͷ͔ʢRailsͷ࿩ʣ
   

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5. ϑΥϩʔɾϑΥϩϫʔͷؔ܎
   ͪΌͪΌ·Δ͸δϡϯΛϑΥϩʔ͍ͯ͠Δ(following)
   δϡϯ͸ͪΌͪΌ·ΔʹϑΥϩʔ͞Ε͍ͯΔ
   (followed)
   ͪΌͪΌ·Δ δϡϯ
   following
   followed
   
   

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6. ྫɿϢʔβʔද
   JE OBNF
   ͪΌͪΌ·Δ
   αϒϨ
   δϡϯ
   

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7. ϑΥϩʔΛ࣮૷͢Δʁ
   JE OBNF GPMMPXFS@JE GPMMPXFE@JE
   ͪΌͪΌ·Δ
   αϒϨ
   δϡϯ
   
   

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8. ໰୊఺
   JE OBNF GPMMPXFS@JE GPMMPXFE@JE
   ͪΌͪΌ·Δ
   αϒϨ
   δϡϯ
   - 1ͭͷηϧʹෳ਺ͷ஋͕ೖΔ
   - ֤ྻͷ஋ΛҰҙʹܾΊΒΕͳ͘ͳΔͷͰɺDBͰ͸NG
   
   

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9. 2ͭͷςʔϒϧΛ࢖͏
   6TFS
   JE OBNF
   ͪΌͪΌ·Δ
   αϒϨ
   δϡϯ
   GSJFOETIJQ
   GPMMPXFS@JE GPMMPXFE@JE
   
   
   
   
   
   

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10. RailsͰ͜ͷؔ܎Λදݱ͢Δʹ͸ʁ
    - RailsͰ͸ɺΞϓϦέʔγϣϯ͕ѻ͏σʔλͱखଓ͖
    ͸Ϟσϧʹॻ͘
    - UserϞσϧͱFriendshipϞσϧ
    - ̎ͭͷϞσϧͷؒʹؔ܎͕͋Δ͜ͱΛఆٛ͢Δ
    - belongs_to, has_manyΛ࢖͏
    
    

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11. belongs_toؔ࿈෇͚
    - ࣗ෼ͷϞσϧͱ૬खͷϞσϧ͕1:1ͷؔ܎Ͱ͋Δ
    - ଞํͷϞσϧʹॴଐ(belongs_to)͢Δ
    - book ͔Βݟͯ author(ஶऀ)͸ඞͣ1ਓ
    Ҿ༻ɿIUUQTSBJMTHVJEFTKQBTTPDJBUJPO@CBTJDTIUNM
    

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12. FriendshipϞσϧ
    class Friendship < ApplicationRecord
    belongs_to :follower, # 関係の名前
    class_name: "User" # 関係先モデル名
    belongs_to :followed,
    class_name: "User"
    end
    
    6TFS
    JE OBNF
    ͪΌͪΌ·Δ
    αϒϨ
    δϡϯ
    GSJFOETIJQ
    GPMMPXFS@JE GPMMPXFE@JE
    
    
    
    
    'SJFOETIJQͱ6TFS͸ͷؔ܎
    

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13. has_manyؔ࿈෇͚
    Ҿ༻ɿIUUQTSBJMTHVJEFTKQBTTPDJBUJPO@CBTJDTIUNM
    - ࣗ෼ͷϞσϧͱ૬खͷϞσϧͱ͕1:ଟͷؔ܎Ͱ͋Δ
    - ૬खͷϞσϧΛॴ༗(has_many)͢Δ
    - author ͸ෳ਺ͷ book Λ࣋ͪ͏Δ
    

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14. UserϞσϧ(following) 1
    class User < ApplicationRecord
    has_many :active_relationships, # Friendshipの言い換え
    class_name: "Friendship", # 関連先クラス名
    foreign_key: "follower_id", # 関連するカラム名
    dependent: :destroy # 関連先が削除されたときに削除する
    ...
    end
    
    6TFS
    JE OBNF
    ͪΌͪΌ·Δ
    αϒϨ
    δϡϯ
    GSJFOETIJQ
    GPMMPXFS@JE GPMMPXFE@JE
    
    
    
    
    6TFSͱ'SJFOETIJQ͸ଟͷؔ܎
    

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15. UserϞσϧ(following) 2
    class User < ApplicationRecord
    ...
    has_many :following, # カラム名
    through: :active_relationships, # active_relationshipsを通して
    source: :followed # 関連付け先モデル名
    ...
    end
    6TFS͕BDUJWF@SFMBUJPOTIJQTΛ௨ͯ͠
    GPMMPXFEͱଟɿଟͷؔ܎Λ࡞Δ
    

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16. UserϞσϧ(followed)
    class User < ApplicationRecord
    has_many :passive_relationships,
    class_name: "Friendship",
    foreign_key: "followed_id",
    dependent: :destroy
    has_many :followers,
    through: :passive_relationships,
    source: :follower
    ...
    end
    
    GPMMPXJOHͱ΄΅ಉ͡
    ˞TPVSDFGPMMPXFS͸ඞਢͰ͸ͳ͍͕GPMMPXJOH
    ͱܗΛ͋ΘͤΔͨΊʹॻ͍ͯ͋Δ
    

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17. σʔλͷؔ࿈෇͚͕Ͱ͖ͨ
    ϑΥϩʔػೳΛ࣮૷͢Δʹ͸follow/unfollowϝιου
    Λ࡞ͬͨΓɺ
    ίϯτϩʔϥͱϏϡʔΛ࣮૷ͨ͠Γ͢Δඞཁ͕͋Δ
    ͕ɺ
    ͜ͷLTͰ͸ׂѪ
    
    

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18. Ϟσϧಉ࢜ͷؔ܎͸has_many, belongs_toͳͲͰදͤ
    Δ
    Ϟσϧ໊ͷݴ͍׵͑Λͯ͠ɺUserͱFriendshipʹ
    followerͱfollowedͷ2ͭͷؔ܎Λ࡞Δ
    ·ͱΊ
    
    

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19. ࢀߟจݙͳͲ
    ୡਓʹֶͿDBઃܭ పఈࢦೆॻ
    https://www.amazon.co.jp/dp/B00EE1XPAI/
    RailsΨΠυ Active Record ͷؔ࿈෇͚
    https://railsguides.jp/association_basics.html
    ʲRailsνϡʔτϦΞϧʳϑΥϩʔػೳͷΞιγΤʔγϣϯΛղઆͯ͠ΈΔ
    https://sado-tech.hateblo.jp/entry/2018/08/17/201629
    RailsνϡʔτϦΞϧ ୈ14ষ ϢʔβʔΛϑΥϩʔ͢Δ
    https://railstutorial.jp/chapters/following_users?version=5.1#cha-following_users
    keynoteςϯϓϨʔτ
    https://github.com/yulily100/Material-Color-Keynote
    highlight
    https://github.com/taggon/highlight
    
    

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