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feat(input_schema): Custom error messages #567

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a0104c3
feat(input_schema): Custom error messages
mfori Nov 11, 2025
631fce4
Merge branch 'master' into feat/custom-error-message
mfori Nov 11, 2025
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50 changes: 50 additions & 0 deletions packages/input_schema/src/input_schema.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,48 @@ const [fieldDefinitions, subFieldDefinitions] = Object
return acc;
}, [[], []]);

/**
* Retrieves a custom error message defined in the schema for a particular schema path.
* @param rootSchema json schema object
* @param schemaPath schema path to the failed validation keyword,
* as provided in an AJV error object, including the keyword at the end, e.g. "#/properties/name/type"
*/
export function getCustomErrorMessage(rootSchema: Record<string, any>, schemaPath: string): string | null {
if (!schemaPath) return null;

const pathParts = schemaPath
.replace(/^#\//, '')
.split('/')
.filter(Boolean);
Comment on lines +52 to +55
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@valekjo valekjo Nov 13, 2025

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Note: I was wondering how AJV deals with / in schemaPath and it seems it escapes it as ~1

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@mfori mfori Nov 13, 2025

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Yep, I did try it too :)


// The last part is the keyword
const keyword = pathParts.pop();
if (!keyword) return null;

// Navigate through the schema to find the relevant fragment
let schemaFragment: Record<string, any> = rootSchema;
for (const key of pathParts) {
if (schemaFragment && typeof schemaFragment === 'object') {
schemaFragment = schemaFragment[key];
} else {
return null;
}
}

if (typeof schemaFragment !== 'object') {
return null;
}

const { errorMessage } = schemaFragment;
if (!errorMessage) return null;

if (typeof errorMessage === 'object' && keyword in errorMessage) {
return errorMessage[keyword];
}

return null;
}

/**
* This function parses AJV error and transforms it into a readable string.
*
Expand Down Expand Up @@ -68,6 +110,14 @@ export function parseAjvError(
return name.replace(/^\/|\/$/g, '').replace(/\//g, '.');
};

// First, try to get a custom error message from the schema
// If found, use it directly and skip further processing
const customError = getCustomErrorMessage({ properties }, error.schemaPath);
if (customError) {
fieldKey = cleanPropertyName(error.instancePath);
return { fieldKey, message: customError };
}

// If error is with keyword type, it means that type of input is incorrect
// this can mean that provided value is null
if (error.keyword === 'type') {
Expand Down
17 changes: 11 additions & 6 deletions packages/input_schema/src/utilities.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ import { countries } from 'countries-list';
import { PROXY_URL_REGEX, URL_REGEX } from '@apify/consts';
import { isEncryptedValueForFieldSchema, isEncryptedValueForFieldType } from '@apify/input_secrets';

import { parseAjvError } from './input_schema';
import { getCustomErrorMessage, parseAjvError } from './input_schema';
import { m } from './intl';

/**
Expand Down Expand Up @@ -197,7 +197,8 @@ export function validateInputUsingValidator(
if (!check.test(item.key)) invalidIndexes.push(index);
});
if (invalidIndexes.length) {
fieldErrors.push(m('inputSchema.validation.arrayKeysInvalid', {
const customError = getCustomErrorMessage(inputSchema, `properties/${property}/patternKey`);
fieldErrors.push(customError ?? m('inputSchema.validation.arrayKeysInvalid', {
rootName: 'input',
fieldKey: property,
invalidIndexes: invalidIndexes.join(','),
Expand All @@ -213,7 +214,8 @@ export function validateInputUsingValidator(
if (!check.test(item.value)) invalidIndexes.push(index);
});
if (invalidIndexes.length) {
fieldErrors.push(m('inputSchema.validation.arrayValuesInvalid', {
const customError = getCustomErrorMessage(inputSchema, `properties/${property}/patternValue`);
fieldErrors.push(customError ?? m('inputSchema.validation.arrayValuesInvalid', {
rootName: 'input',
fieldKey: property,
invalidIndexes: invalidIndexes.join(','),
Expand All @@ -228,7 +230,8 @@ export function validateInputUsingValidator(
if (!check.test(item)) invalidIndexes.push(index);
});
if (invalidIndexes.length) {
fieldErrors.push(m('inputSchema.validation.arrayValuesInvalid', {
const customError = getCustomErrorMessage(inputSchema, `properties/${property}/patternValue`);
fieldErrors.push(customError ?? m('inputSchema.validation.arrayValuesInvalid', {
rootName: 'input',
fieldKey: property,
invalidIndexes: invalidIndexes.join(','),
Expand All @@ -246,7 +249,8 @@ export function validateInputUsingValidator(
if (!check.test(key)) invalidKeys.push(key);
});
if (invalidKeys.length) {
fieldErrors.push(m('inputSchema.validation.objectKeysInvalid', {
const customError = getCustomErrorMessage(inputSchema, `properties/${property}/patternKey`);
fieldErrors.push(customError ?? m('inputSchema.validation.objectKeysInvalid', {
rootName: 'input',
fieldKey: property,
invalidKeys: invalidKeys.join(','),
Expand All @@ -262,7 +266,8 @@ export function validateInputUsingValidator(
if (typeof propertyValue !== 'string' || !check.test(propertyValue)) invalidKeys.push(key);
});
if (invalidKeys.length) {
fieldErrors.push(m('inputSchema.validation.objectValuesInvalid', {
const customError = getCustomErrorMessage(inputSchema, `properties/${property}/patternValue`);
fieldErrors.push(customError ?? m('inputSchema.validation.objectValuesInvalid', {
rootName: 'input',
fieldKey: property,
invalidKeys: invalidKeys.join(','),
Expand Down
87 changes: 65 additions & 22 deletions packages/json_schemas/schemas/input.schema.json
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,8 @@
"type": "array",
"items": { "type": "string" },
"minItems": 1
}
},
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "enum"],
"if": {
Expand Down Expand Up @@ -124,7 +125,8 @@
"maxLength": { "type": "integer" },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" },
"isSecret": { "enum": [false] }
"isSecret": { "enum": [false] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"unevaluatedProperties": false,
"allOf": [
Expand Down Expand Up @@ -171,7 +173,8 @@
"editor": { "enum": ["textfield", "textarea", "hidden"] },
"isSecret": { "enum": [true] },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
}
}
},
Expand Down Expand Up @@ -206,7 +209,8 @@
"placeholderValue": { "type": "string" },
"patternKey": { "type": "string" },
"patternValue": { "type": "string" },
"isSecret": { "enum": [false] }
"isSecret": { "enum": [false] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"unevaluatedProperties": false,
"allOf": [
Expand Down Expand Up @@ -303,7 +307,8 @@
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" },
"items": { "$ref": "#/definitions/arrayItems" },
"isSecret": { "enum": [true] }
"isSecret": { "enum": [true] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
}
}
},
Expand Down Expand Up @@ -347,7 +352,8 @@
},
"additionalProperties": {
"type": "boolean"
}
},
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"unevaluatedProperties": false,
"allOf": [
Expand Down Expand Up @@ -402,7 +408,8 @@
},
"additionalProperties": {
"type": "boolean"
}
},
"errorMessage": { "$ref": "#/definitions/errorMessage" }
}
}
},
Expand All @@ -422,7 +429,8 @@
"unit": { "type": "string" },
"editor": { "enum": ["number", "hidden"] },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand Down Expand Up @@ -451,7 +459,8 @@
"unit": { "type": "string" },
"editor": { "enum": ["number", "hidden"] },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand Down Expand Up @@ -479,7 +488,8 @@
"groupDescription": { "type": "string" },
"editor": { "enum": ["checkbox", "hidden"] },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand Down Expand Up @@ -521,7 +531,8 @@
"minLength": { "type": "integer" },
"maxLength": { "type": "integer" },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "resourceType"],
"allOf": [
Expand Down Expand Up @@ -580,7 +591,8 @@
"uniqueItems": { "type": "boolean" },
"resourceType": { "enum": ["dataset", "keyValueStore", "requestQueue"] },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "resourceType"],
"allOf": [
Expand Down Expand Up @@ -632,7 +644,8 @@
"nullable": { "type": "boolean" },
"editor": { "enum": ["json", "hidden"] },
"sectionCaption": { "type": "string" },
"sectionDescription": { "type": "string" }
"sectionDescription": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "editor"],
"if": {
Expand Down Expand Up @@ -667,7 +680,8 @@
"type": "array",
"items": { "type": "string" },
"minItems": 1
}
},
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "enum"],
"if": {
Expand All @@ -694,7 +708,8 @@
"nullable": { "type": "boolean" },
"minLength": { "type": "integer" },
"maxLength": { "type": "integer" },
"editor": { "enum": ["javascript", "python", "textfield", "textarea", "datepicker", "hidden", "fileupload"] }
"editor": { "enum": ["javascript", "python", "textfield", "textarea", "datepicker", "hidden", "fileupload"] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"allOf": [
Expand Down Expand Up @@ -746,7 +761,8 @@
"placeholderKey": { "type": "string" },
"placeholderValue": { "type": "string" },
"patternKey": { "type": "string" },
"patternValue": { "type": "string" }
"patternValue": { "type": "string" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"unevaluatedProperties": false,
Expand Down Expand Up @@ -842,7 +858,8 @@
"minimum": { "type": "integer" },
"maximum": { "type": "integer" },
"unit": { "type": "string" },
"editor": { "enum": ["number", "hidden"] }
"editor": { "enum": ["number", "hidden"] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand All @@ -869,7 +886,8 @@
"minimum": { "type": "number" },
"maximum": { "type": "number" },
"unit": { "type": "string" },
"editor": { "enum": ["number", "hidden"] }
"editor": { "enum": ["number", "hidden"] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand All @@ -895,7 +913,8 @@
"nullable": { "type": "boolean" },
"groupCaption": { "type": "string" },
"groupDescription": { "type": "string" },
"editor": { "enum": ["checkbox", "hidden"] }
"editor": { "enum": ["checkbox", "hidden"] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand Down Expand Up @@ -933,7 +952,8 @@
},
"additionalProperties": {
"type": "boolean"
}
},
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description"],
"if": {
Expand Down Expand Up @@ -973,7 +993,8 @@
"nullable": { "type": "boolean" },
"pattern": { "type": "string" },
"minLength": { "type": "integer" },
"maxLength": { "type": "integer" }
"maxLength": { "type": "integer" },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "resourceType"],
"if": {
Expand Down Expand Up @@ -1013,7 +1034,8 @@
"minItems": { "type": "integer" },
"maxItems": { "type": "integer" },
"uniqueItems": { "type": "boolean" },
"resourceType": { "enum": ["dataset", "keyValueStore", "requestQueue"] }
"resourceType": { "enum": ["dataset", "keyValueStore", "requestQueue"] },
"errorMessage": { "$ref": "#/definitions/errorMessage" }
},
"required": ["type", "title", "description", "resourceType"],
"if": {
Expand Down Expand Up @@ -1548,6 +1570,27 @@
"required": ["type"]
}
}
},
"errorMessage": {
"title": "Utils: Custom error message definition",
"type": "object",
"properties": {
"type": { "type": "string" },
"pattern": { "type": "string" },
"minLength": { "type": "string" },
"maxLength": { "type": "string" },
"enum": { "type": "string" },
"minimum": { "type": "string" },
"maximum": { "type": "string" },
"minItems": { "type": "string" },
"maxItems": { "type": "string" },
"uniqueItems": { "type": "string" },
"minProperties": { "type": "string" },
"maxProperties": { "type": "string" },
"patternKey": { "type": "string" },
"patternValue": { "type": "string" }
},
"additionalProperties": false
}
}
}
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