Merge pull request #140 from canjs/improve-type-error-message

Improve type error message
canjs · Oct 11, 2019 · 5c56ee7 · 5c56ee7
2 parents 83be9f4 + ea5b2c2
commit 5c56ee7
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Showing 2 changed files with 34 additions and 1 deletion.
diff --git a/src/define.js b/src/define.js
@@ -24,7 +24,8 @@ var newSymbol = Symbol.for("can.new"),
 	inSetupSymbol = Symbol.for("can.initializing"),
 	isMemberSymbol = Symbol.for("can.isMember"),
 	hasBeenDefinedSymbol = Symbol.for("can.hasBeenDefined"),
-	canMetaSymbol = Symbol.for("can.meta");
+	canMetaSymbol = Symbol.for("can.meta"),
+	baseTypeSymbol = Symbol.for("can.baseType");
 
 var eventsProto, define,
 	make, makeDefinition, getDefinitionsAndMethods, getDefinitionOrMethod;
@@ -688,6 +689,18 @@ make = {
 					return setter;
 				} else {
 					return function setter(newValue){
+						//!steal-remove-start
+						if(process.env.NODE_ENV !== 'production') {
+							try {
+								return set.call(this, canReflect.convert(newValue, type));
+							} catch (error) {
+								var typeName = canReflect.getName(type[baseTypeSymbol]);
+								var message  = newValue +  ' is not of type ' + typeName + '. Property ' + prop + ' is using "type: ' + typeName + '". ';
+								message += 'Use "' + prop + ': type.convert(' + typeName + ')" to automatically convert values to ' + typeName + 's when setting the "' + prop + '" property.';
+								throw new Error(message);
+							}
+						}
+						//!steal-remove-end
 						return set.call(this, canReflect.convert(newValue, type));
 					};
 				}

diff --git a/test/define-test.js b/test/define-test.js
@@ -2,6 +2,8 @@ const QUnit = require("steal-qunit");
 const { mixinObject } = require("./helpers");
 const { hooks } = require("../src/define");
 const canReflect = require("can-reflect");
+const type = require('can-type');
+const dev = require("can-test-helpers").dev;
 
 QUnit.module("can-observable-mixin - define()");
 
@@ -188,3 +190,21 @@ QUnit.test("properties using value behavior reset when unbound", function(assert
 
 	assert.equal(obj.derivedProp, undefined, "value reset");
 });
+
+dev.devOnlyTest('On error include the name of the property that is being set', function(assert) {
+	class Person extends mixinObject() {
+		static get props() {
+			return {
+				age: type.check(Number)
+			};
+		}
+	}
+
+	var farah = new Person();
+
+	try {
+		farah.age = '4';
+	} catch (error) {
+		assert.equal(error.message, '4 is not of type Number. Property age is using "type: Number". Use "age: type.convert(Number)" to automatically convert values to Numbers when setting the "age" property.');
+	}
+});