How to surface custom CastError messages?

[joshkopecek]

We're working on mongoose-geojson-schema, which adds validation for GeoJSON objects to Mongoose schemas. Following the guidance on creating a Custom Schema Type in the mongoose docs we're using

throw new mongoose.SchemaType.CastError('Crs must be an object or null');

referenced here
Yet when we test the code and review the exceptions thrown, they are generic messages:

Cast to Point failed for value "[object Object]" at path "point"

How can the user find out the detailed error message? Is there something else that we need to in the plugin, or something else the user does on the calling side?

Thanks in advance for any help here.

[markstos]

This is similar to, if not the same issue as #3162.

[vkarpov15]

Right now a CastError has a reason property that contains the original error. Unfortunately the custom schema type examples currently prevent that property from getting populated though. To work around this, just throw any error type that isn't mongoose's CastError and you'll get the reason property.

[joshkopecek]

@vkarpov15 thanks for looking at this. I've changed to using Error instead, which is definitely more meaningful than the generic CastError. We'll wait on the milestone release for switching back to CastError. @markstos

[vkarpov15]

You can also just use your own error type, a casterror gets surfaced in the end anyway

[markstos]

Thanks for the tip!