DRAFT: feat(pat-validation): Support definition of minimum or maximum number of selections.

Author: thet

src/pat/validation/validation.js

@@ -25,6 +25,8 @@ parser.addArgument("message-equality", "is not equal to %{attribute}.");
 parser.addArgument("not-after", null);
 parser.addArgument("not-before", null);
 parser.addArgument("equality", null);
+parser.addArgument("min-selection", null);
+parser.addArgument("max-selection", null);
 parser.addArgument("delay", 100); // Delay before validation is done to avoid validating while typing.
 
 // BBB
@@ -255,6 +257,35 @@ class Pattern extends BasePattern {
                     logger.debug("Check `no-before` input.", not_after_el);
                     this.check_input({ input: not_before_el, stop: true });
                 }
+            } else if (input_options.minSelection || input_options.maxSelection)
+                // This makes only sense for inputs with the same name.
+                const valued_siblings = [...this.el.elements].filter((el) => {
+                    // Filter for siblings with same name.
+                    if (el.name !== input.name) {
+                        return false;
+                    }
+
+                    // Check if they are selected or have an value
+                    if (el.type === "checkbox" || el.type === "radio") {
+                        return el.checked;
+                    }
+
+                    // ... or have a value set.
+                    return el.value !== undefined;
+                });
+
+                if (valued_siblings > input_options.maxSelection) {
+                    this.set_error({
+                        input: input,
+                        msg: "You have exceeded the maximum number of selections."
+                    })
+                }
+                if (valued_siblings < input_options.minSelection) {
+                    this.set_error({
+                        input: input,
+                        msg: "You need to select at least..."
+                    })
+                }
             }
 
             if (!validity_state.customError) {