1 files changed, 73 insertions, 0 deletions
diff --git a/addons/mail/static/src/model/model_field_command.js b/addons/mail/static/src/model/model_field_command.js
new file mode 100644
index 00000000..f4e59a95
--- /dev/null
+++ b/addons/mail/static/src/model/model_field_command.js
@@ -0,0 +1,73 @@
+odoo.define('mail/static/src/model/model_field_command.js', function (require) {
+'use strict';
+
+/**
+ * Allows field update to detect if the value it received is a command to
+ * execute (in which was it will be an instance of this class) or an actual
+ * value to set (in all other cases).
+ */
+class FieldCommand {
+    /**
+     * @constructor
+     * @param {function} func function to call when executing this command. 
+     * The function should ALWAYS return a boolean value 
+     * to indicate whether the value changed.
+     */
+    constructor(func) {
+        this.func = func;
+    }
+
+    /**
+     * @param {ModelField} field
+     * @param {mail.model} record
+     * @param {options} [options]
+     * @returns {boolean} whether the value changed for the current field
+     */
+    execute(field, record, options) {
+        return this.func(field, record, options);
+    }
+}
+
+/**
+ * Returns a clear command to give to the model manager at create/update.
+ */
+function clear() {
+    return new FieldCommand((field, record, options) =>
+        field.clear(record, options)
+    );
+}
+
+/**
+ * Returns a decrement command to give to the model manager at create/update.
+ *
+ * @param {number} [amount=1]
+ */
+function decrement(amount = 1) {
+    return new FieldCommand((field, record, options) => {
+        const oldValue = field.get(record);
+        return field.set(record, oldValue - amount, options);
+    });
+}
+
+/**
+ * Returns a increment command to give to the model manager at create/update.
+ *
+ * @param {number} [amount=1]
+ */
+function increment(amount = 1) {
+    return new FieldCommand((field, record, options) => {
+        const oldValue = field.get(record);
+        return field.set(record, oldValue + amount, options);
+    });
+}
+
+return {
+    // class
+    FieldCommand,
+    // shortcuts
+    clear,
+    decrement,
+    increment,
+};
+
+});