Various API updates.

app/Rules/IsBoolean.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace FireflyIII\Rules;
+
+use Illuminate\Contracts\Validation\Rule;
+
+/**
+ * Class IsBoolean
+ */
+class IsBoolean implements Rule
+{
+    /**
+     * Get the validation error message.
+     *
+     * @return string
+     */
+    public function message(): string
+    {
+        return (string)trans('validation.boolean');
+    }
+
+    /**
+     * Determine if the validation rule passes.
+     *
+     * @param  string $attribute
+     * @param  mixed  $value
+     *
+     * @return bool
+     */
+    public function passes($attribute, $value): bool
+    {
+        if (\is_bool($value)) {
+            return true;
+        }
+        if (\is_int($value) && 0 === $value) {
+            return true;
+        }
+        if (\is_int($value) && 1 === $value) {
+            return true;
+        }
+        if (\is_string($value) && '1' === $value) {
+            return true;
+        }
+        if (\is_string($value) && '0' === $value) {
+            return true;
+        }
+        if (\is_string($value) && 'true' === $value) {
+            return true;
+        }
+        if (\is_string($value) && 'false' === $value) {
+            return true;
+        }
+
+        return false;
+    }
+}