PaulUithol/Backbone-relational

previous attributes broken when another attributes changed in handler.

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#485 创建于 2014年8月18日

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 (0 评论) (0 反应) (0 负责人)JavaScript (2,343 star) (344 fork)batch import
bughelp wanted

描述

Scenario:

  • has model with several listeners on some property propA
  • one of the listener change another property propB.
  • In rest of handlers for propA previousAttributes contains new value of propA instead old one.

In case of usage regular Model instead of RelationalModel previousAttributes contains old value as expected.

sample: http://jsfiddle.net/4ohq1tho/1

this cause several issues like https://github.com/kmalakoff/knockback/issues/121

贡献者指南

技术栈
javascript
领域
frontend
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-3 hours
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
needs investigation
前置要求
Backbone model event handlingJavaScript event loop
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
30
研究方向
Investigate the order of change event handlers in Backbone relational vs Backbone.Model. The issue is that when multiple listeners on propertyA exist, and one changes propertyB, subsequent listeners see the new value of propertyA in `previousAttributes`. Look into the Backbone source code for `change` event propagation and how RelationalModel overrides it. Compare with the regular Backbone.Model behavior. The jsfiddle provides a reproduction. Focus on the `set` method and how `previousAttributes` is stored before triggering events. Potentially modify the RelationalModel's set method to preserve the original previousAttributes across handler calls.