1 .. -*- coding: utf-8 -*- |
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2 |
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3 |
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4 Developing the user interface with Views |
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5 ======================================== |
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6 |
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7 XXXFIXME MERGE THIS WITH 05-define-views.en.txt |
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8 |
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9 Before moving to this section, make sure you read the `Essentials` |
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10 section in the Introduction. |
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11 |
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12 Tip: when modifying views, you do not need to restart the local |
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13 server. Just save the file in your editor and reload the page in your |
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14 browser to see the changes. |
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15 |
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16 The selection/view principle |
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17 ---------------------------- |
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18 |
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19 With `LAX`, views are defined by Python classes. A view includes: |
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20 |
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21 - an identifier (all objects in `LAX` are entered in a registry |
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22 and this identifier will be used as a key) |
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23 |
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24 - a filter to select the resulsets it can be applied to |
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25 |
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26 `LAX` provides a lot of standard views, for a complete list, you |
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27 will have to read the code in directory ``ginco/web/views/`` (XXX |
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28 improve doc). |
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29 |
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30 For example, the view named ``primary`` is the one used to display |
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31 a single entity. |
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32 |
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33 If you want to change the way a ``BlogEntry`` is displayed, just |
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34 override the view ``primary`` in ``BlogDemo/views.py`` :: |
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35 |
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36 01. from ginco.web.views import baseviews |
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37 02. |
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38 03. class BlogEntryPrimaryView(baseviews.PrimaryView): |
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39 04. |
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40 05. accepts = ('BlogEntry',) |
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41 06. |
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42 07. def cell_call(self, row, col): |
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43 08. entity = self.entity(row, col) |
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44 09. self.w(u'<h1>%s</h1>' % entity.title) |
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45 10. self.w(u'<p>published on %s in category %s</p>' % \ |
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46 11. (entity.publish_date.strftime('%Y-%m-%d'), entity.category)) |
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47 12. self.w(u'<p>%s</p>' % entity.text) |
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48 |
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49 The above source code defines a new primary view (`line 03`) for |
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50 ``BlogEntry`` (`line 05`). |
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51 |
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52 Since views are applied to resultsets and resulsets can be tables of |
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53 data, it is needed to recover the entity from its (row,col) |
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54 coordinates (`line 08`). We will get to this in more detail later. |
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55 |
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56 The view has a ``self.w()`` method that is used to output data. Here `lines |
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57 09-12` output HTML tags and values of the entity's attributes. |
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58 |
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59 When displaying same blog entries as before, you will notice that the |
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60 page is now looking much nicer. |
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61 |
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62 .. image:: images/lax-book.09-new-view-blogentry.en.png |
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63 :alt: blog entries now look much nicer |
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64 |
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65 Let us now improve the primary view of a blog :: |
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66 |
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67 01. class BlogPrimaryView(baseviews.PrimaryView): |
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68 02. |
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69 03. accepts = ('Blog',) |
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70 04. |
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71 05. def cell_call(self, row, col): |
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72 06. entity = self.entity(row, col) |
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73 07. self.w(u'<h1>%s</h1>' % entity.title) |
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74 08. self.w(u'<p>%s</p>' % entity.description) |
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75 09. rset = self.req.execute('Any E WHERE E entry_of B, B eid "%s"' % entity.eid) |
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76 10. self.wview('primary', rset) |
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77 |
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78 In the above source code, `lines 01-08` are similar to the previous |
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79 view we defined. |
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80 |
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81 At `line 09`, a simple request in made to build a resultset with all |
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82 the entities linked to the current ``Blog`` entity by the relationship |
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83 ``entry_of``. The part of the framework handling the request knows |
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84 about the schema and infer that such entities have to be of the |
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85 ``BlogEntry`` kind and retrieves them. |
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86 |
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87 The request returns a selection of data called a resultset. At |
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88 `line 10` the view 'primary' is applied to this resultset to output |
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89 HTML. |
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90 |
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91 **This is to be compared to interfaces and protocols in object-oriented |
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92 languages. Applying a given view to all the entities of a resultset only |
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93 requires the availability, for each entity of this resultset, of a |
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94 view with that name that can accepts the entity.** |
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95 |
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96 Assuming we added entries to the blog titled `MyLife`, displaying it |
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97 now allows to read its description and all its entries. |
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98 |
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99 .. image:: images/lax-book.10-blog-with-two-entries.en.png |
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100 :alt: a blog and all its entries |
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101 |
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102 **Before we move forward, remember that the selection/view principle is |
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103 at the core of `LAX`. Everywhere in the engine, data is requested |
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104 using the RQL language, then HTML/XML/text/PNG is output by applying a |
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105 view to the resultset returned by the query. That is where most of the |
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106 flexibility comes from.** |
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107 |
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108 [WRITE ME] |
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109 |
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110 * implementing interfaces, calendar for blog entries |
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111 * show that a calendar view can export data to ical |
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112 |
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113 We will implement the ginco.interfaces.ICalendarable interfaces on |
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114 entities.BloEntry and apply the OneMonthCalendar and iCalendar views |
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115 to resultsets like "Any E WHERE E is BlogEntry" |
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116 |
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117 * create view "blogentry table" with title, publish_date, category |
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118 |
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119 We will show that by default the view that displays |
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120 "Any E,D,C WHERE E publish_date D, E category C" is the table view. |
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121 Of course, the same can be obtained by calling |
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122 self.wview('table',rset) |
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123 |
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124 * in view blog, select blogentries and apply view "blogentry table" |
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125 * demo ajax by filtering blogentry table on category |
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126 |
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127 we did the same with 'primary', but with tables we can turn on filters |
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128 and show that ajax comes for free. |
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