[ADD] web_context_tunnel

help solving the new arguments passing to on change method in addons

web_context_tunnel/__openerp__.py

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+{
+    'name': 'Web Context Tunnel',
+    'category': 'Hidden',
+    'author': 'Akretion',
+    'license': 'AGPL-3',
+    'description':"""
+Web Context Tunnel.
+===================
+
+The problem with OpenERP on_changes
+-----------------------------------
+
+OpenERP uses to pass on_change Ajax events arguments using positional
+arguments. This is annoying as modules often need to pass extra arguments
+that are not present in the base on_change signatures. As soon as two modules
+try to alter this signature to add their extra arguments, they are incompatible
+between them unless some extra glue module make them compatible again by
+taking all extra arguments into account. But this leads to a combinatorial 
+explosion to make modules compatible again.
+
+The solution
+------------
+
+This module provides a simple work around that will work in most of the cases.
+In fact it works if the base on_change is designed to pass the context
+argument. Else it won't work and you should go the old way. But in any case
+it's a bad practice if an on_change doesn't pass the context argument and you
+can certainly rant about these bad on_changes to the the context added in the
+arguments.
+
+So for an on_change passing the context, how does this module works?
+
+Well OpenERP already has an elegant solution for an extension module to alter
+an XML attributes: put an extension point in the view using
+position="attributes" and then redefine the attribute. That is already used at
+several places to replace the "context" attribute that the client will send to
+the server.
+
+The idea here is to wrap the extra arguments needed by your on_change inside
+that context dictionary just as it were a regular Python kwargs. That context
+should then be automatically propagated accross the on_change call chain,
+no matter of the module order and without any need to hack any on_change
+signature.
+
+The issue with just position="attributes" and redefining the context, is that
+again, if two independent modules redefine the context, they are incompatible
+unless a third module accounts for both of them.
+
+But with this module, an extension point can now use position="attributes" and
+instead of redefining the "context" attribute, you will now just define a new
+"context_foo" attribute this way:
+<attribute name="context_foo">{'my_extra_field': my_extra_field}</attribute>.
+
+This module modifies the web client in such a way that before sending the Ajax
+on_change event request to the server, all the node attributes starting with
+"context" are merged into a single context dictionnary, keeping the keys and
+values from all extensions. In the rare case a module really wants to override
+the value in context, then it needs to still override the original context
+attribute (or the other original attribute).
+
+And of course, if you should call your on_change by API or webservice instead
+of using the web client, simply ensure you are wrapping the required extra
+arguments in the context dictionary.
+
+Tests
+-----
+
+This module comes with a simple test in static/test/context_tunnel.js.
+To run it, open the page /web/tests?mod=web_context_tunnel in your browser
+as explained here https://doc.openerp.com/trunk/web/testing
+It should also by picked by the Python testing when testing with PhantomJS.
+
+As for testing modules using web_context_tunnel with YAML, yes it's possible.
+In fact you need to manually mimic the new web-client behavior by manually
+ensuring you add the extra context keys you will need later in your on_change.
+For instance, before the on_change is called, you can alter the context with
+a !python statement like context.update({'my_extra_field': my_extra_field}).
+
+You can see an example of module conversion to use web_context_tunnel here
+for instance:
+https://github.com/openerpbrasil/l10n_br_core/compare/develop...feature%2Fsale-web-context-tunnel
+""",
+    'version': '2.0',
+    'depends': ['web'],
+    'js': ['static/src/js/context_tunnel.js'],
+    'test': [
+        'static/test/context_tunnel.js',
+    ],
+    'css': [],
+    'auto_install': False,
+    'web_preload': False,
+}

web_context_tunnel/static/src/js/context_tunnel.js

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+openerp.web_context_tunnel = function(instance) {
+
+    instance.web.form.FormWidget.prototype.build_context = function() {
+        var v_context = false;
+        var fields_values = false;
+        // instead of using just the attr context, we merge any attr starting with context
+        for (var key in this.node.attrs) {
+            if (key.substring(0, 7) === "context") {
+                if (!v_context) {
+                    fields_values = this.field_manager.build_eval_context();
+                    v_context = new instance.web.CompoundContext(this.node.attrs[key]).set_eval_context(fields_values);
+                } else {
+                    v_context = new instance.web.CompoundContext(this.node.attrs[key], v_context).set_eval_context(fields_values);
+                }
+
+            }
+        }
+        if (!v_context) {
+            v_context = (this.field || {}).context || {};
+        }
+        return v_context;
+    };
+};
+
+
+// vim:et fdc=0 fdl=0:

web_context_tunnel/static/test/context_tunnel.js

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+openerp.testing.section('context_tunnel', {
+}, function (test) {
+    test.dependencies = window['oe_all_dependencies'];
+    test("context composition", function (instance) {
+        var field_manager = new instance.web.form.DefaultFieldManager();
+        var node = {'attrs': {'context': {'key1': 'value1', 'key2': 'value2'}, 'context_2': {'key3': 'value3'}, 'context_3': {'key4': 'value4'}}}
+        var w = new instance.web.form.FormWidget(field_manager, node);
+        var context = w.build_context().eval();
+        ok(context['key1'] === 'value1', 'right value for key1 in context');
+        ok(context['key2'] === 'value2', 'right value for key2 in context');
+        ok(context['key3'] === 'value3', 'right value for key3 in context');
+        ok(context['key4'] === 'value4', 'right value for key4 in context');
+    });
+});