ngrx：为实体设置默认值

Question

如何在 ngrx 实体中启动状态时为实体设置默认值？

potato.model.ts

export class Potato {
    id: number;
    weight: number;
}

potato.reducer.ts

export interface PotatoState extends EntityState<Potato> { }

export const potatoAdapter: EntityAdapter<Potato> = createEntityAdapter<Potato>();

const potatoesInitialState: PotatoState = potatoAdapter.getInitialState();

export const initialState: State = {
    potatoes: potatoesInitialState
};

export function reducer(state = initialState, action: PotatoActions): State {
    switch (action.type) {
        // ...
    }
}

例如我需要设置默认权重0.2。

Answer 1

我建议你为此使用默认构造函数：

export class Potato {
    id: number;
    weight: number;

    constructor() {
        weight = 0.2;
    }
}

Answer 2

您不应该在存储中添加类以使其可序列化，好吧，您的马铃薯是，但很容易在其中添加函数，因为它存在，然后就不再存在了。

我会改用工厂函数来创建 Potato。

interface Potato {
  id: number;
  weight: number;
}

const createPotato = (potato: Potato = { id: undefined, weight: 0.2 }) => potato;

console.log(createPotato());
console.log(createPotato({id: 20, weight: 300}));

ngrx：为实体设置默认值

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