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Merged
merged 4 commits into from
Oct 24, 2018
Merged

feat(warn): warn when an existing property starting with $ is not pro… #8214

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8604075
feat(warn): warn when an existing property starting with $ is not pro…
posva May 21, 2018
8dd1b54
feat(warn): add case for properties starting with _
posva May 21, 2018
abe72a7
refactor(warn): rename warnStartingWithDollar -> warnReservedPrefix
posva May 21, 2018
690d9b9
Update render-proxy.spec.js
posva May 31, 2018
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19 changes: 16 additions & 3 deletions src/core/instance/proxy.js
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,16 @@ if (process.env.NODE_ENV !== 'production') {
)
}

const warnStartingWithDollar = (target, key) => {
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Something like warnPreservedPrefix?

warn(
`Property "${key}" must be accessed with "$data.${key}" because ` +
'properties starting with "$" or "_" are not proxied in the Vue instance to ' +
'prevent conflicts with Vue internals' +
'See: https://vuejs.org/v2/api/#data',
target
)
}

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Should we do the same thing when we come across properties prefixed with _?

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that's true, I thought there is an eslint warning for it. Let me check again

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I added that as well but I wonder if it is correct. I'm not sure what babel helpers are we talking about in 8e1478e

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Why not proxying both? I changed all mixins in a big project to respect this rule on Style Guide (https://vuejs.org/v2/style-guide/#Private-property-names-essential) and now when I am trying to pass it to a component prop it gets there undefined because it is not being proxied

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to prevent conflicts. We cannot check all existing properties (which would be ideal), for conflicts, so we test that instead.
Nowadays, if you want to create plugins that inject custom properties, using Symbols is probably the safest way

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@mcskeeled mcskeeled May 21, 2018 •
edited
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Yet the style guide recommends it, I think this issue should be given some thought, either change the rule for private property names or proxy everything, (maybe giving a warning in development process). Not proxying this is removing functionality and forcing developers that follow the recommended style guide find workarounds because of limited functionality to prevent others who may not read the documentation and override vue properties.

const hasProxy =
typeof Proxy !== 'undefined' && isNative(Proxy)

Expand All @@ -45,9 +55,11 @@ if (process.env.NODE_ENV !== 'production') {
const hasHandler = {
has (target, key) {
const has = key in target
const isAllowed = allowedGlobals(key) || (typeof key === 'string' && key.charAt(0) === '_')
const isAllowed = allowedGlobals(key) ||
(typeof key === 'string' && key.charAt(0) === '_' && !(key in target.$data))
if (!has && !isAllowed) {
warnNonPresent(target, key)
if (key in target.$data) warnStartingWithDollar(target, key)
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Does it have to be some property starting with preserved prefixes here? It feels a little weird to me that after these checks we concluded that the property starts with _ or $.

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if the key is in $data it is not proxified, then it can only be starting with those 2 characters. That's what I was thinking

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Proxying properties starting with $_ would be an option

else warnNonPresent(target, key)
}
return has || !isAllowed
}
Expand All @@ -56,7 +68,8 @@ if (process.env.NODE_ENV !== 'production') {
const getHandler = {
get (target, key) {
if (typeof key === 'string' && !(key in target)) {
warnNonPresent(target, key)
if (key in target.$data) warnStartingWithDollar(target, key)
else warnNonPresent(target, key)
}
return target[key]
}
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45 changes: 45 additions & 0 deletions test/unit/features/instance/render-proxy.spec.js
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Expand Up @@ -45,5 +45,50 @@ if (typeof Proxy !== 'undefined') {

expect(vm.$el.textContent).toBe('foo')
})

it('should warn properties starting with $ when found', () => {
new Vue({
data: { $a: 'foo' },
template: `<div>{{ $a }}</div>`
}).$mount()
expect(`Property "$a" must be accessed with "$data.$a"`).toHaveBeenWarned()
})

it('should warn properties starting with _ when found', () => {
new Vue({
data: { _foo: 'foo' },
template: `<div>{{ _foo }}</div>`
}).$mount()
expect(`Property "_foo" must be accessed with "$data._foo"`).toHaveBeenWarned()
})

it('should warn properties starting with $ when not found', () => {
new Vue({
template: `<div>{{ $a }}</div>`
}).$mount()
expect(`Property or method "$a" is not defined`).toHaveBeenWarned()
expect(`Property "$a" must be accessed with "$data.$a"`).not.toHaveBeenWarned()
})

it('should warn properties starting with $ when not found (with stripped)', () => {
const render = function (h) {
return h('p', this.$a)
}
render._withStripped = true
new Vue({
data: { $a: 'foo' },
render
}).$mount()
expect(`Property "$a" must be accessed with "$data.$a"`).toHaveBeenWarned()
})

it('should not warn properties starting with $ when using $data to access', () => {
new Vue({
data: { $a: 'foo' },
template: `<div>{{ $data.$a }}</div>`
}).$mount()
expect(`Property or method "$a" is not defined`).not.toHaveBeenWarned()
expect(`Property or method "$a" is not defined`).not.toHaveBeenWarned()
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These two expects are identical, is that accidental?

})
})
}