示例

Manage unloaded association state with Ecto.Association.NotLoaded, handle put_assoc exceptions on uninitialized associations, and track retained parent state across build_assoc and apply_changes

sha256:273ee8a646360bca1986c52809ca47909c22e94a5026a62c46b23c56c2eefb3d

案例

目标

Manage unloaded association state with Ecto.Association.NotLoaded, handle put_assoc exceptions on uninitialized associations, and track retained parent state across build_assoc and apply_changes HOW

包

ecto 3.14.1

环境

elixir

创建时间

2026-08-17T04:43:50Z

常见的想当然

A competent developer expects put_assoc/4 to associate child records directly onto any struct or changeset, assuming schema association fields default to empty collections or nil when newly constructed.

这是本样本作者记下的、开发者或模型在此处通常会有的预期。下面的契约才是真正运行过的东西。

契约

• Calling put_assoc/4 on a loaded struct with unloaded associations raises RuntimeError because uninitialized associations hold an %Ecto.Association.NotLoaded{} struct rather than nil or [], and Ecto.assoc_loaded?/1 returns false.
• Explicitly initializing the association field on the struct to [] (for has_many) or nil (for has_one/belongs_to) marks the association as loaded with Ecto.assoc_loaded?/1 returning true, allowing put_assoc/4 to succeed on loaded structs.
• Calling Ecto.build_assoc/3 constructs the child schema struct with the parent's primary key mapped to foreign keys, but leaves the parent struct's association field retained as %Ecto.Association.NotLoaded{}.
• Executing apply_changes/1 updates fields and embeds into structs while preserving %Ecto.Association.NotLoaded{} on untouched associations, and leaves prepare_changes/2 lifecycle callbacks unexecuted.
• Passing parameters with unpermitted fields to cast/4 populates changeset.changes with permitted fields only, but retains all unpermitted and sensitive keys in changeset.params.

文件

• NOTES.md
• csx.json
• mix.exs
• mix.lock
• test/contract.exs
• test/test_helper.exs

下载源代码构件 (tar.gz)

原始种子者

csx-seed

验证回执

• elixir 1 · linux alpine/x64 · docker · CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-17 · ed25519:d91480838ac982c9