feat: validation types (#17)

src/core/builders/create-form-validator.spec.ts

@@ -0,0 +1,35 @@
+import { assert, IsExact } from "conditional-type-checks";
+
+import { FormValidator } from "../types/form-validator";
+
+import { createFormSchema } from "./create-form-schema";
+import { createFormValidator } from "./create-form-validator";
+
+describe("createFormValidator", () => {
+  const Schema = createFormSchema(
+    fields => ({
+      string: fields.string(),
+      choice: fields.choice("A", "B", "C"),
+      num: fields.number(),
+      bool: fields.bool(),
+    }),
+    errors => errors<"err1" | "err2">()
+  );
+
+  it("resolves ok", () => {
+    const formValidator = createFormValidator(Schema, _validate => []);
+
+    type Actual = typeof formValidator;
+    type Expected = FormValidator<
+      {
+        string: string;
+        choice: "A" | "B" | "C";
+        num: number | "";
+        bool: boolean;
+      },
+      "err1" | "err2"
+    >;
+
+    assert<IsExact<Actual, Expected>>(true);
+  });
+});

src/core/builders/create-form-validator.ts

@@ -0,0 +1,43 @@
+import { FormSchema } from "../types/form-schema";
+import {
+  FieldValidator,
+  FormValidator,
+  ValidateFn,
+} from "../types/form-validator";
+
+/**
+ * Create form validator based on provided set of validation rules.
+ * Error type of all validation rules is specified by the FormSchema.
+ * You can also specify validation dependencies between fields and validation triggers.
+ *
+ * @example
+ * ```
+ * const validator = createForm.validator(Schema, validate => [
+ *   validate({
+ *     field: Schema.password,
+ *     rules: () => [required(), minLength(6)]
+ *   }),
+ *   validate({
+ *     field: Schema.passwordConfirm,
+ *     dependencies: [Schema.password],
+ *     triggers: ["blur", "submit"],
+ *     rules: (password) => [
+ *       required(),
+ *       val => val === password ? null : { code: "passwordMismatch" },
+ *     ]
+ *   }),
+ *   validate.each({
+ *     field: Schema.promoCodes,
+ *     rules: () => [optional(), exactLength(6)],
+ *   })
+ * ])
+ * ```
+ */
+export const createFormValidator = <Values extends object, Err>(
+  _schema: FormSchema<Values, Err>,
+  _builder: (
+    validate: ValidateFn
+  ) => Array<FieldValidator<unknown, Err, unknown[]>>
+): FormValidator<Values, Err> => {
+  return {} as any;
+};

src/core/hooks/use-formts/use-formts.ts

@@ -22,6 +22,7 @@ import {
   objectDescriptorKeys,
   _DescriptorApprox_,
 } from "../../types/form-schema-approx";
+import { FormValidator } from "../../types/form-validator";
 import { impl, opaque } from "../../types/type-mapper-util";
 
 import { createInitialValues } from "./create-initial-values";
@@ -38,6 +39,9 @@ export type FormtsOptions<Values extends object, Err> = {
    * The defaults depend on field type (defined in the Schema).
    */
   initialValues?: DeepPartial<Values>;
+
+  /** Form validator created using `createForm.validator` function (optional). */
+  validator?: FormValidator<Values, Err>;
 };
 
 type FormtsReturn<Values extends object, Err> = [

src/core/types/form-validator.spec.ts

@@ -0,0 +1,87 @@
+import { assert, IsExact } from "conditional-type-checks";
+
+import { FieldDescriptor } from "./field-descriptor";
+import { FieldValidator, ValidateFn } from "./form-validator";
+
+const validator: ValidateFn = (() => {}) as any;
+
+describe("validateFn", () => {
+  type Err = { code: "err1" | "err2" };
+  const fd1: FieldDescriptor<string, Err> = {} as any;
+  const fd2: FieldDescriptor<number, Err> = {} as any;
+  const fd3: FieldDescriptor<"a" | "b" | "c", Err> = {} as any;
+  const fd4: FieldDescriptor<Date[], Err> = {} as any;
+  const fd5: FieldDescriptor<{ parent: { child: string[] } }, Err> = {} as any;
+
+  it("resolves properly for string", () => {
+    const stringFieldValidator = validator({
+      field: fd1,
+      dependencies: [fd2, fd3],
+      rules: (_number, _choice) => [false],
+    });
+
+    type Actual = typeof stringFieldValidator;
+    type Expected = FieldValidator<string, Err, [number, "a" | "b" | "c"]>;
+
+    assert<IsExact<Actual, Expected>>(true);
+  });
+
+  it("resolves properly for choice", () => {
+    const choiceFieldValidator = validator({
+      field: fd3,
+      dependencies: [fd1, fd4],
+      rules: (_string, _dateArray) => [false],
+    });
+
+    type Actual = typeof choiceFieldValidator;
+    type Expected = FieldValidator<"a" | "b" | "c", Err, [string, Date[]]>;
+
+    assert<IsExact<Actual, Expected>>(true);
+  });
+
+  it("resolves properly for array", () => {
+    const arrayFieldValidator = validator({
+      field: fd4,
+      dependencies: [fd1, fd2, fd3, fd5],
+      rules: (_string, _number, _choice, _obj) => [false],
+    });
+
+    type Actual = typeof arrayFieldValidator;
+    type Expected = FieldValidator<
+      Date[],
+      Err,
+      [string, number, "a" | "b" | "c", { parent: { child: string[] } }]
+    >;
+
+    assert<IsExact<Actual, Expected>>(true);
+  });
+
+  it("resolves properly for object array", () => {
+    const objFieldValidator = validator({
+      field: fd5,
+      dependencies: [fd1],
+      rules: _string => [false],
+    });
+
+    type Actual = typeof objFieldValidator;
+    type Expected = FieldValidator<
+      { parent: { child: string[] } },
+      Err,
+      [string]
+    >;
+
+    assert<IsExact<Actual, Expected>>(true);
+  });
+
+  it("resolves properly with no dependencies", () => {
+    const fieldValidator = validator({
+      field: fd1,
+      rules: () => [false],
+    });
+
+    type Actual = typeof fieldValidator;
+    type Expected = FieldValidator<string, Err, []>;
+
+    assert<IsExact<Actual, Expected>>(true);
+  });
+});

src/core/types/form-validator.ts

@@ -0,0 +1,62 @@
+import { Falsy } from "../../utils";
+
+import { FieldDescriptor } from "./field-descriptor";
+
+/**
+ * Function responsible for validating single field.
+ *
+ * @param value - value to be validated of type `T`
+ *
+ * @returns validation error of type `Err`, or `null` when field is valid
+ */
+export type Validator<T, Err> = Validator.Sync<T, Err>;
+// | Validator.Async<T, Err>;
+
+export namespace Validator {
+  export type Sync<T, Err> = {
+    (value: T): Err | null;
+  };
+  export type Async<T, Err> = {
+    (value: T): Promise<Err | null>;
+  };
+}
+
+export type ValidationTrigger = "change" | "blur" | "submit";
+
+export type FormValidator<Values extends object, Err> = {
+  validate: (
+    fields: Array<FieldDescriptor<unknown, Err>>,
+    getValue: <P>(field: FieldDescriptor<P, Err>) => P,
+    trigger?: ValidationTrigger
+  ) => Array<{ field: FieldDescriptor<unknown, Err>; error: Err | null }>;
+};
+
+export type FieldValidator<T, Err, Dependencies extends any[]> = {
+  type: "inner" | "outer";
+  field: FieldDescriptor<T, Err>;
+  validators: (...deps: [...Dependencies]) => Array<Falsy | Validator<T, Err>>;
+  triggers?: Array<ValidationTrigger>;
+  dependencies?: readonly [...FieldDescTuple<Dependencies>];
+};
+
+export type ValidateFn = {
+  each: ValidateEachFn;
+
+  <T, Err, Dependencies extends any[]>(config: {
+    field: FieldDescriptor<T, Err>;
+    triggers?: ValidationTrigger[];
+    dependencies?: readonly [...FieldDescTuple<Dependencies>];
+    rules: (...deps: [...Dependencies]) => Array<Falsy | Validator<T, Err>>;
+  }): FieldValidator<T, Err, Dependencies>;
+};
+
+export type ValidateEachFn = <T, Err, Dependencies extends any[]>(config: {
+  field: FieldDescriptor<T[], Err>;
+  triggers?: ValidationTrigger[];
+  dependencies?: readonly [...FieldDescTuple<Dependencies>];
+  rules: (...deps: [...Dependencies]) => Array<Falsy | Validator<T, Err>>;
+}) => FieldValidator<T[], Err, Dependencies>;
+
+type FieldDescTuple<ValuesTuple extends readonly any[]> = {
+  [Index in keyof ValuesTuple]: FieldDescriptor<ValuesTuple[Index]>;
+};

src/utils/utility-types.ts

@@ -29,3 +29,5 @@ export type DeepPartial<T> = T extends Function
 export type IdentityDict<T extends string> = IsUnion<T> extends true
   ? { [K in T]: K }
   : never;
+
+export type Falsy = null | undefined | false;