Added and fixed gettext usage for better translation coverage. Fixes #5284

1) Fixed usage gettext('') instead of _('') in javascript files.
  2) Fixed usage gettext('') instead of `${gettext('')}` in javascript files,
     because "pybabel extract" not support extracting from this syntax.

web/pgadmin/tools/schema_diff/__init__.py

@@ -36,7 +36,7 @@ class SchemaDiffModule(PgAdminModule):
         A module class for Schema Diff derived from PgAdminModule.
     """
 
-    LABEL = "Schema Diff"
+    LABEL = gettext("Schema Diff")
 
     def get_own_menuitems(self):
         return {}
@@ -439,7 +439,7 @@ def compare(trans_id, source_sid, source_did, source_scid,
 
     comparison_result = []
 
-    diff_model_obj.set_comparison_info("Comparing objects...", 0)
+    diff_model_obj.set_comparison_info(gettext("Comparing objects..."), 0)
     update_session_diff_transaction(trans_id, session_obj,
                                     diff_model_obj)
 
@@ -451,7 +451,8 @@ def compare(trans_id, source_sid, source_did, source_scid,
         for node_name, node_view in all_registered_nodes.items():
             view = SchemaDiffRegistry.get_node_view(node_name)
             if hasattr(view, 'compare'):
-                msg = "Comparing " + view.blueprint.COLLECTION_LABEL
+                msg = gettext('Comparing {0}').\
+                    format(gettext(view.blueprint.COLLECTION_LABEL))
                 diff_model_obj.set_comparison_info(msg, total_percent)
                 # Update the message and total percentage in session object
                 update_session_diff_transaction(trans_id, session_obj,
@@ -468,7 +469,7 @@ def compare(trans_id, source_sid, source_did, source_scid,
                     comparison_result = comparison_result + res
             total_percent = total_percent + node_percent
 
-        msg = "Successfully compare the specified schemas."
+        msg = gettext("Successfully compare the specified schemas.")
         total_percent = 100
         diff_model_obj.set_comparison_info(msg, total_percent)
         # Update the message and total percentage done in session object
@@ -501,7 +502,7 @@ def poll(trans_id):
     msg, diff_percentage = diff_model_obj.get_comparison_info()
 
     if diff_percentage == 100:
-        diff_model_obj.set_comparison_info("Comparing objects...", 0)
+        diff_model_obj.set_comparison_info(gettext("Comparing objects..."), 0)
         update_session_diff_transaction(trans_id, session_obj,
                                         diff_model_obj)
 

web/pgadmin/tools/schema_diff/compare.py

@@ -12,6 +12,7 @@
 import copy
 
 from flask import render_template
+from flask_babelex import gettext
 from pgadmin.utils.driver import get_driver
 from config import PG_DEFAULT_DRIVER
 from pgadmin.utils.ajax import internal_server_error
@@ -86,7 +87,7 @@ class SchemaDiffObjectCompare:
         return compare_dictionaries(self, source_params, target_params,
                                     target_schema, source, target,
                                     self.node_type,
-                                    self.blueprint.COLLECTION_LABEL,
+                                    gettext(self.blueprint.COLLECTION_LABEL),
                                     self.keys_to_ignore)
 
     def ddl_compare(self, **kwargs):

web/pgadmin/tools/schema_diff/model.py

@@ -7,6 +7,8 @@
 #
 ##########################################################################
 
+from flask_babelex import gettext
+
 
 class SchemaDiffModel(object):
     """
@@ -30,7 +32,7 @@ class SchemaDiffModel(object):
             **kwargs : N number of parameters
         """
         self._comparison_result = dict()
-        self._comparison_msg = 'Comparision started...'
+        self._comparison_msg = gettext('Comparision started...')
         self._comparison_percentage = 0
 
     def clear_data(self):

web/pgadmin/tools/schema_diff/static/js/schema_diff.backform.js

@@ -289,11 +289,11 @@ let SchemaDiffHeaderView = Backform.Form.extend({
   },
   template: _.template(`
     <div class="row pgadmin-control-group">
-      <div class="col-1 control-label">Select Source</div>
+      <div class="col-1 control-label">` + gettext('Select Source') + `</div>
       <div class="col-6 source row"></div>
     </div>
     <div class="row pgadmin-control-group">
-      <div class="col-1 control-label">Select Target</div>
+      <div class="col-1 control-label">` + gettext('Select Target') + `</div>
       <div class="col-6 target row"></div>
       <div class="col-5 target-buttons">
           <div class="action-btns d-flex">
@@ -421,9 +421,9 @@ let SchemaDiffFooterView = Backform.Form.extend({
   template: {
     'content': _.template(`
        <div class="pg-el-sm-12 row <%=contentClass%>">
-                  <div class="pg-el-sm-4 ddl-source">Source</div>
-                  <div class="pg-el-sm-4 ddl-target">Target</div>
-                  <div class="pg-el-sm-4 ddl-diff">Difference
+                  <div class="pg-el-sm-4 ddl-source">` + gettext('Source') + `</div>
+                  <div class="pg-el-sm-4 ddl-target">` + gettext('Target') + `</div>
+                  <div class="pg-el-sm-4 ddl-diff">` + gettext('Difference') + `
                   </div>
               </div>
       </div>

web/pgadmin/tools/schema_diff/static/js/schema_diff.js

@@ -85,7 +85,7 @@ define('pgadmin.schemadiff', [
       })
         .done(function(res) {
           self.trans_id = res.data.schemaDiffTransId;
-          res.data.panel_title = 'Schema Diff (Beta)'; //TODO: Set the panel title
+          res.data.panel_title = gettext('Schema Diff (Beta)'); //TODO: Set the panel title
           // TODO: Following function is used to test the fetching of the
           // databases this should be moved to server selection event later.
           self.launch_schema_diff(res.data);

web/pgadmin/tools/schema_diff/static/js/schema_diff_ui.js

@@ -302,11 +302,11 @@ export default class SchemaDiffUI {
     var grid_width =  (self.grid_width - 47) / 2 ;
     var columns = [
       checkboxSelector.getColumnDefinition(),
-      {id: 'title', name: 'Schema Objects', field: 'title', minWidth: grid_width, formatter: formatColumnTitle},
-      {id: 'status', name: 'Comparison Result', field: 'status', minWidth: grid_width},
-      {id: 'label', name: 'Schema Objects', field: 'label',  width: 0, minWidth: 0, maxWidth: 0,
+      {id: 'title', name: gettext('Schema Objects'), field: 'title', minWidth: grid_width, formatter: formatColumnTitle},
+      {id: 'status', name: gettext('Comparison Result'), field: 'status', minWidth: grid_width},
+      {id: 'label', name: gettext('Schema Objects'), field: 'label',  width: 0, minWidth: 0, maxWidth: 0,
         cssClass: 'really-hidden', headerCssClass: 'really-hidden'},
-      {id: 'type', name: 'Schema Objects', field: 'type',  width: 0, minWidth: 0, maxWidth: 0,
+      {id: 'type', name: gettext('Schema Objects'), field: 'type',  width: 0, minWidth: 0, maxWidth: 0,
         cssClass: 'really-hidden', headerCssClass: 'really-hidden'},
       {id: 'id', name: 'id', field: 'id', width: 0, minWidth: 0, maxWidth: 0,
         cssClass: 'really-hidden', headerCssClass: 'really-hidden' },
@@ -462,10 +462,10 @@ export default class SchemaDiffUI {
       .done(function (res) {
         let msg = res.data.compare_msg;
         if (res.data.diff_percentage != 100) {
-          msg = msg + ' (this may take a few minutes)...';
+          msg = msg + gettext(' (this may take a few minutes)...');
         }
 
-        msg = msg + '<br>'+ res.data.diff_percentage + '% completed.';
+        msg = msg + '<br>' + gettext('%s completed.', res.data.diff_percentage + '%');
         $('#diff_fetching_data').find('.schema-diff-busy-text').html(msg);
       })
       .fail(function (xhr) {