Rails使用serialize存储数组时表单提交数组为空如何解决

核心错误出在表单字段的name属性生成逻辑不符合Rails参数解析规则：
你当前使用的<%= f.number_field 'team_a_sets[]' %>写法，会生成错误的name属性tournament_match[team_a_sets[]]，Rails解析这类参数时无法正确识别为数组元素，只会返回空数组。

1. 修改表单字段配置 #

给每个数组输入框显式指定正确的name属性，示例如下：

<%= form_with model: @tournament_match, url: update_tennis_game_result_tournament_match_path(@tournament_match), method: :patch do |f| %>

  <%= f.label :team_a, 'Team A' %>
  <%= f.number_field :team_a_sets, name: 'tournament_match[team_a_sets][]' %>
  <%= f.number_field :team_a_sets, name: 'tournament_match[team_a_sets][]' %>
  <%= f.number_field :team_a_sets, name: 'tournament_match[team_a_sets][]' %>
  <%= f.number_field :team_a_sets, name: 'tournament_match[team_a_sets][]' %>
  <%= f.number_field :team_a_sets, name: 'tournament_match[team_a_sets][]' %><br>

  <%= f.label :team_b, 'Team B' %>
  <%= f.number_field :team_b_sets, name: 'tournament_match[team_b_sets][]' %>
  <%= f.number_field :team_b_sets, name: 'tournament_match[team_b_sets][]' %>
  <%= f.number_field :team_b_sets, name: 'tournament_match[team_b_sets][]' %>
  <%= f.number_field :team_b_sets, name: 'tournament_match[team_b_sets][]' %>
  <%= f.number_field :team_b_sets, name: 'tournament_match[team_b_sets][]' %><br>

  <%= f.submit 'Submit', class: 'btn btn-primary btn-block' %>
<% end %>

注意：顺便修正了Team B的label指向错误，原代码里Team B的label关联的是:team_a

2. 可选：优化空值过滤逻辑 #

如果允许用户留空部分局分输入框，可以在强参数中过滤空值并统一转为数字，避免存储无效空字符串：

def tennis_params
  params.require(:tournament_match).permit(:match_result, team_a_sets: [], team_b_sets: []).tap do |param|
    param[:team_a_sets] = param[:team_a_sets].reject(&:blank?).map(&:to_i)
    param[:team_b_sets] = param[:team_b_sets].reject(&:blank?).map(&:to_i)
  end
end

3. 可选：Rails 5+ 原生数组字段优化 #

如果使用PostgreSQL作为数据库，可直接在迁移中声明数组类型字段，无需额外配置serialize：

def change
  add_column :tournament_matches, :team_a_sets, :integer, array: true, default: []
  add_column :tournament_matches, :team_b_sets, :integer, array: true, default: []
end

内容的提问来源于stack exchange，提问作者r3b00t