如何通过将值设置为变量来更新LiveData [英] How to update LiveData by set a value to variable

问题描述

我有一个变量和一个LiveData，我想在为该变量设置一个值时更新LiveData.

I have a variable and a LiveData, and I want to update the LiveData when I set a value to the variable.

var trigger = ""
val updateValue: LiveData<Value> = service.getValue(trigger)

// when set the value1 to trigger, the updateValue need to update the value.
var trigger = "value1"
val updateValue: LiveData<Value> = service.getValue("value1")

推荐答案

使用 switchmap :

var trigger = MutableLiveData<String>()
val updateValue: LiveData<Value> = Transformations.switchMap(trigger) {
        service.getValue(it)
}

然后:

trigger.value = "value1"

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