Calling 'document. getSymbols()' will result in an error

hejie615

When calling "document. getSymbols ()" after using the component library component, an error will be reported
var document = sketch.getSelectedDocument() let symbols = document.getSymbols() console.log(symbols)
MOJavaScriptException: TypeError: null is not an object (evaluating 'this.getOwningPage().selection') get SketchAPI.js:1:88574 index.js:362:23 forEach [native code] formatValue index.js:358:38 formatProperty index.js:733:22 formatArray index.js:707:31 formatValue index.js:457:25 formatProperty index.js:733:22 formatObject index.js:469:31 formatValue index.js:457:25

hejie615

No errors will be reported without using symbols

rodionovd

Do you have a sample document to help reproduce this error?

hejie615

rodionovd The example is not very convenient to provide, but it is due to the introduction of a local component library. When using the components in the document and obtaining information about the components, an error will be reported

rodionovd

hejie615 you're quite right, I've just managed to reproduce this error when printing a library symbol with at least one override point via console.log.

The problem seems be to that Override.selected property getter doesn't quite work well for library symbols and console.log does query this property when printing out a symbol.

I've reported this bug to Sketch, but in the meantime the only workaround I can think of is to use log() or print() instead of console.log for printing out library symbols and to avoid using Override.selected property on them.

hejie615

rodionovd 'console. log' is just an example. When using the symbolMaster of the library, an error will be reported, such as' JSON. stringify (symbolMaster) '. However, when directly using the properties of symbolMaster, there will be no problem, such as directly using symbolMaster.name

rodionovd

hejie615 Indeed, console.log does basically the same thing as stringify before printing an object, thus the same error.

hejie615

rodionovd Yes, when I obtain and use it, an error will be reported. So how should I avoid this error now

rodionovd

hejie615 So I'm not a JS expert, but I believe one possible workaround would be to mark Override.selected property as non-exportable so it will be skipped when iterating properties in toJSON():

// Call this function on a symbol master as soon as you get it from the API (e.g. via `document.getSymbols()`)
function workaround_disableOverrideSelectedProperty(master) {
  master.overrides.forEach(o => {
    o.constructor["_DefinedPropertiesKey"]["selected"].exportable = false
  })
}

// ...

const sketch = require('sketch')

let document = sketch.getSelectedDocument()
let symbol = document.getSymbols()[0]

// This will raise TypeError
// console.log(symbol)

workaround_disableOverrideSelectedProperty(symbol)

// Prints just fine by skipping all `overrides[n].selected` properties
console.log(symbol)
// This also works without errrors
print(JSON.stringify(symbol))