Support for readOnly / writeOnly

[shaoner]

hello,

Thanks for the great library.

I was wondering if there is any plan to support readOnly / writeOnly

If the property is marked as readOnly being true and is in the required list, the required will take effect on the response only

Basically right now, if a schema contains properties marked as readOnly or writeOnly and required, the validation fails for both request and response because ajv just ignores readOnly / writeOnly fields.

If not, I can probably work on a PR later this month to omit readOnly / writeOnly properties from the required array (respectively for request / response)

[anttiviljami]

Hi there @alexlren! I had not heard about readOnly / writeOnly before but that seems very cool. I would of course absolutely love it if you had the chance to look at implementing this for openapi-backend with a PR!

[elby22]

@alexlren I think I have accomplished the readOnly portion of this this using customizeAjv and Lodash (have not written tests for it yet)

const customizeAjv: AjvCustomizer = (ajv, opts, context) => {
	const options = { ...opts };
	const customAjv = new Ajv(options);

	// Ensure readOnly
	if (context === ValidationContext.RequestBody || context === ValidationContext.Params) {
		customAjv.removeKeyword('readOnly');
		customAjv.addKeyword('readOnly', {
			compile: (schema) => {
				return (data, dataPath, parentData, parentDataProperty, rootData) => {
					const isReadOnly = schema;
					let isValid = true;
					if (isReadOnly === true) {
						// strip leading dot from dataPath for lodash to use
						const path = dataPath.substring(1);
						const value = _.get(rootData, path, undefined);
						isValid = value === undefined;
					}
					return isValid;
				};
			},
		});
	}

	return customAjv as any; 
};

I am using something similar for writeOnly in another portion of my stack, which I can share the code for. You could easily use the validateResponse handler to redact writeOnly properties.
I might make a PR for this if we think this is a good approach.

[BlakeHyde]

Has anyone else had luck with this? It seems like the ajv customization API has changed since the snippet above was written.