feat: support custom required validation messages

packages/validation/src/index.ts

@@ -22,6 +22,8 @@ export type RuleDescriptor =
 export interface FieldDescriptor {
   type: "string" | "number" | "boolean";
   optional?: boolean;
+  /** Message used when a required field is empty. Defaults to "Required". */
+  requiredMessage?: string;
   label?: string;
   /** Trim string input before validating. */
   trim?: boolean;
@@ -103,13 +105,20 @@ export function checkField(
 ): { value: unknown; error: string | null } {
   if (desc.type === "boolean") {
     const value = raw === true || raw === "true" || raw === "on";
-    if (!desc.optional && !value) return { value, error: "Required" };
+    if (!desc.optional && !value) {
+      return { value, error: desc.requiredMessage || "Required" };
+    }
     return { value, error: null };
   }
 
   const pre = desc.trim && typeof raw === "string" ? raw.trim() : raw;
   const empty = pre === undefined || pre === null || pre === "";
-  if (empty) return { value: undefined, error: desc.optional ? null : "Required" };
+  if (empty) {
+    return {
+      value: undefined,
+      error: desc.optional ? null : desc.requiredMessage || "Required",
+    };
+  }
 
   let value: unknown;
   if (desc.type === "number") {
@@ -133,6 +142,7 @@ type Refinement = { fn: (value: unknown) => boolean | string; message?: string }
 abstract class FieldSchema {
   abstract readonly type: "string" | "number" | "boolean";
   protected _optional = false;
+  protected _requiredMessage?: string;
   protected _label?: string;
   protected _default?: unknown;
   protected rules: RuleDescriptor[] = [];
@@ -142,6 +152,12 @@ abstract class FieldSchema {
     this._optional = true;
     return this;
   }
+  /** Require a non-empty value and optionally replace the default message. */
+  required(message = "Required"): this {
+    this._optional = false;
+    this._requiredMessage = message;
+    return this;
+  }
   label(label: string): this {
     this._label = label;
     return this;
@@ -183,6 +199,7 @@ abstract class FieldSchema {
     return {
       type: this.type,
       optional: this._optional || undefined,
+      requiredMessage: this._requiredMessage,
       label: this._label,
       rules: this.rules,
     };

packages/validation/src/runtime.ts

@@ -42,11 +42,11 @@ export const VALIDATE_RUNTIME = String.raw`
   function checkField(desc, raw) {
     if (desc.type === "boolean") {
       var b = raw === true || raw === "true" || raw === "on";
-      return (!desc.optional && !b) ? "Required" : null;
+      return (!desc.optional && !b) ? (desc.requiredMessage || "Required") : null;
     }
     var pre = desc.trim && typeof raw === "string" ? raw.trim() : raw;
     var empty = pre === undefined || pre === null || pre === "";
-    if (empty) return desc.optional ? null : "Required";
+    if (empty) return desc.optional ? null : (desc.requiredMessage || "Required");
     var value;
     if (desc.type === "number") { value = Number(pre); if (isNaN(value)) return "Must be a number"; }
     else value = String(pre);