feat: add validator for string integer

README.md

@@ -32,6 +32,7 @@ yarn add @byndyusoft/class-validator-extended class-validator class-transformer
 
 - [AtLeastOneDefined](./src/decorators/validators/atLeastOneDefined.ts)
 - [IsNullable](./src/decorators/validators/isNullable.ts)
+- [IsIntString](./src/decorators/validators/math/isIntString.ts)
 - [LessThan](./src/decorators/validators/math/lessThan.ts)
 - [LessThanOrEqualTo](./src/decorators/validators/math/lessThanOrEqualTo.ts)
 - [GreaterThan](./src/decorators/validators/math/greaterThan.ts)

src/decorators/validators/__tests__/math/isIntString.spec.ts

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2023 Byndyusoft
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { validate, ValidationError } from "class-validator";
+
+import { IsIntString } from "~/src";
+
+class Box {
+  @IsIntString()
+  public readonly height!: string;
+
+  public constructor(height: string) {
+    this.height = height;
+  }
+}
+
+describe("decorators/validators/IsIntString", () => {
+  describe("when values are valid", () => {
+    const height = "99";
+    const box = new Box(height);
+
+    it("does not have validation errors", async () => {
+      const validationErrors = await validate(box);
+
+      expect(validationErrors).toHaveLength(0);
+    });
+  });
+
+  describe("when values are invalid", () => {
+    const cases: Array<{
+      description: string;
+      height: string | number;
+    }> = [
+      {
+        description: "for number",
+        height: 100,
+      },
+      {
+        description: "for string number",
+        height: "100.1",
+      },
+      {
+        description: "for wrong types",
+        height: "abc",
+      },
+    ];
+
+    it.each(cases)(
+      "returns validation errors $description",
+      async ({ height }) => {
+        // @ts-expect-error for validation tests
+        const box = new Box(height);
+
+        const validationErrors = await validate(box);
+
+        expect(validationErrors).toBeArrayOfSize(1);
+
+        expect(validationErrors).toSatisfyAll((error: ValidationError) => {
+          if (!error.constraints) {
+            return false;
+          }
+
+          return "isIntString" in error.constraints;
+        });
+      },
+    );
+  });
+});

src/decorators/validators/math/index.ts

@@ -16,5 +16,6 @@
 
 export * from "./greaterThan";
 export * from "./greaterThanOrEqualTo";
+export * from "./isIntString";
 export * from "./lessThan";
 export * from "./lessThanOrEqualTo";

src/decorators/validators/math/isIntString.ts

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2023 Byndyusoft
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  buildMessage,
+  isString,
+  ValidateBy,
+  ValidationOptions,
+} from "class-validator";
+import { Decimal } from "decimal.js";
+
+const isIntString = (value: unknown): boolean => {
+  try {
+    return isString(value) && new Decimal(value).isInt();
+  } catch {
+    return false;
+  }
+};
+
+export function IsIntString(
+  validationOptions?: ValidationOptions,
+): PropertyDecorator {
+  return ValidateBy(
+    {
+      name: "isIntString",
+      validator: {
+        validate: (value): boolean => isIntString(value),
+        defaultMessage: buildMessage(
+          (eachPrefix) => `${eachPrefix}$property must be a string integer`,
+          validationOptions,
+        ),
+      },
+    },
+    validationOptions,
+  );
+}