Vue advanced (univariate): the solution that the view does not update after the Vue array or object is updated

No Silver Bullet 2020-11-13 07:28:49
vue advanced univariate solution view

In the process of project development , If you bind all page elements to a form , Some elements in the page are not directly obtained , The unexpected effect will appear when getting the page operation value , For example, page elements cannot be reset .

Scene: the repetition

In the use of el-select When designing a form drop-down box , If the length of the drop-down box array returned by the background is 1, The first element is selected by default . The idea is to return the value of the first element directly after the background value Assign a value to el-select Of v-model.

created() {
this.MissionTemplateForm.state = this.StatusOptions[0].display_name

But after the background method returns the value , by el-select Before assignment ,MissionTemplateForm It has been assigned a value response.returnobj, Lead to MissionTemplateForm The structure of is destroyed , So we need to be right MissionTemplateForm Reset the properties in the . Need to use

Vue.set( target, propertyName/index, value )

Everybody knows vue It is a bi-directional binding responsive update view , This auto update view is mainly aimed at data The key of an attribute or object that exists in it , Such as a data:{ test : 'test'}; Modify here test You can automatically update the relevant view with the value of , But if you add a new attribute later and change it It can't be updated automatically , This involves vue Two way binding principle of .

vue The default is to give data attribute Add to scout ( Publisher —— Subscriber pattern ) Upper observation , Respond to view updates if there are changes , The newly added attributes and objects do not perform this step of adding to the observer , Need to be manually added , It needs to be used VUE Of set The method is to .

Parameters :

The first parameter is the array or object you want to modify
{Object | Array} target

The second parameter is the name of the object to be modified or the corresponding subscript
{string | number} propertyName/index

The third parameter wants to modify the value after success

{any} value


The value returned is the third parameter value

Use it directly in your page method

 let obj = this.dryingList[ind];
this.$set(obj, "nodianzanflag", true);

Reference documents

Vue Advanced ( ninety-seven ):vue Add properties and values to an object dynamically

Vue Advanced ( Ninety-eight ):Vue.set() and this.$set() Introduce

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