Added coercing system to field configuration, revised some of the data validation errors

experiments/config.mjs

@@ -0,0 +1,31 @@
+import { Field_Configuration  } from '@efforting.tech/data/field-configuration';
+
+
+function mandatory_anything(value) {
+	return value !== undefined;
+}
+
+
+function string_coercion_function(value) {
+	if (value === undefined) {
+		throw new Error('Undefined not allowed');
+	}
+	return String(value);
+}
+
+
+
+const fc = new Field_Configuration('Some_Field', null, string_coercion_function, 'Anything that could be a string');
+
+console.log(fc.check_validation(undefined));
+console.log(fc.check_validation(true));
+
+console.log([ fc.coerce(123) ]);
+console.log([ fc.coerce(true) ]);
+
+console.log([ fc.load(undefined, 'Some configuration') ]);
+console.log([ fc.load(true) ]);
+
+
+//fc.validate(undefined);
+console.log(fc.load(undefined, 'New thingamabob object'));

experiments/package.json

@@ -3,6 +3,7 @@
 	"type": "module",
 	"dependencies": {
 		"@efforting.tech/errors": "link:../build/packages/errors",
-		"@efforting.tech/rule-processing": "link:../build/packages/rule-processing"
+		"@efforting.tech/rule-processing": "link:../build/packages/rule-processing",
+		"@efforting.tech/data": "link:../build/packages/data"
 	}
 }

package-manifest.yaml

@@ -21,6 +21,12 @@ packages:
     internal-dependencies:
       - errors
 
+  data:
+    path: source/data
+    #documentation: documentation/data
+    description: Data management
+    internal-dependencies:
+      - errors
 
 wip-packages:
   object-graph-storage:

source/data/field-configuration.mjs

@@ -0,0 +1,43 @@
+import { Data_Validation_Failed, Data_Coercion_Failed } from '@efforting.tech/errors';
+
+export class Field_Configuration {
+	constructor(name, validation_function=null, coercion_function=null, expected_description=undefined) {
+		Object.assign(this, { name, validation_function, coercion_function, expected_description });
+	}
+
+	check_validation(value) {
+		const { validation_function } = this;
+		return !validation_function || validation_function(value);
+	}
+
+	validate(value, target=undefined) {
+		const { validation_function, name, expected_description } = this;
+		if (!this.check_validation(value)) {
+			throw new Data_Validation_Failed({
+				name, validation_function, value,
+				target, expected_description,
+			});
+		}
+	}
+
+	coerce(value, target=undefined) {
+		const { coercion_function, name, expected_description } = this;
+		try {
+			return coercion_function ? coercion_function(value) : value;
+		} catch (e) {
+			throw new Data_Coercion_Failed({
+				name, coercion_function, value,
+				target, expected_description,
+				upstream_error: e,
+			})
+		}
+	}
+
+	load(value, target=undefined) {
+		const coerced_value = this.coerce(value, target);
+		this.validate(coerced_value, target);
+		return coerced_value;
+	}
+
+
+}

source/errors.mjs

@@ -1,5 +1,30 @@
 import { inspect } from 'node:util';
 
+// § GROUP: Configuration field errors
+
+export class Data_Validation_Failed extends Error {
+	constructor(data) {
+		const { value, target, expected_description, validation_function, name, upstream_error } = data;
+		const type = value === null ? 'null' : typeof value;
+		const target_info = target ? inspect(target) : 'unknown target';
+		const expected_desc = expected_description ?? `data that would pass validation using ${validation_function}`;
+		const upstream_error_description = upstream_error ? ` Upstream error was: ${upstream_error}` : '';
+		super(`Data validation failed for field "${name}" of ${target_info}. Encountered data of type "${type}" while expecting "${expected_desc}".${upstream_error_description}`);
+		this.data = data;
+	}
+}
+
+export class Data_Coercion_Failed extends Error {
+	constructor(data) {
+		const { value, target, expected_description, coercion_function, name, upstream_error } = data;
+		const type = value === null ? 'null' : typeof value;
+		const target_info = target ? inspect(target) : 'unknown target';
+		const expected_desc = expected_description ?? `data that would be coerced using ${coercion_function}`;
+		const upstream_error_description = upstream_error ? ` Upstream error was: ${upstream_error}` : '';
+		super(`Data coercion failed for field "${name}" of ${target_info}. Encountered data of type "${type}" while expecting "${expected_desc}".${upstream_error_description}`);
+		this.data = data;
+	}
+}
 // § GROUP: Resolving errors
 
 export class Item_Unresolvable extends Error {

tools/stage-for-pnpm.mjs

@@ -89,7 +89,7 @@ for (const [package_name, package_data] of Object.entries(manifest.packages)) {
 	const exports_map = {};
 	for (const file of linked_sources) {
 		const name = path.basename(file, '.mjs');
-		const key = name === pkg.name ? '.' : `./${name}`;
+		const key = name === path.basename(pkg.name) ? '.' : `./${name}`;
 		exports_map[key] =  `./${file}`;
 	}