1 .. _controllers: |
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2 |
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3 Controllers |
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4 ----------- |
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5 |
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6 Overview |
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7 ++++++++ |
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8 |
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9 Controllers are responsible for taking action upon user requests |
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10 (loosely following the terminology of the MVC meta pattern). |
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11 |
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12 The following controllers are provided out-of-the box in CubicWeb. We |
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13 list them by category. |
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14 |
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15 `Browsing`: |
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16 |
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17 * the View controller (web/views/basecontrollers.py) is associated |
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18 with most browsing actions within a CubicWeb application: it always |
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19 instantiates a `main template` and lets the ResultSet/Views dispatch |
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20 system build up the whole content; it handles ObjectNotFound and |
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21 NoSelectableObject errors that may bubble up to its entry point, in |
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22 an end-user-friendly way (but other programming errors will slip |
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23 through) |
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24 |
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25 * the JSon controller (web/views/basecontrollers.py) provides services |
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26 for Ajax calls, typically using JSON as a serialization format for |
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27 input, and sometimes using either JSON or XML for output; |
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28 |
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29 * the Login/Logout controllers (web/views/basecontrollers.py) make |
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30 effective user login or logout requests |
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31 |
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32 `Edition`: |
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33 |
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34 * the Edit controller (see :ref:`edit_controller`) handles CRUD |
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35 operations in response to a form being submitted; it works in close |
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36 association with the Forms, to which it delegates some of the work |
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37 |
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38 * the Form validator controller (web/views/basecontrollers.py) |
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39 provides form validation from Ajax context, using the Edit |
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40 controller, to implement the classic form handling loop (user edits, |
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41 hits 'submit/apply', validation occurs server-side by way of the |
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42 Form validator controller, and the UI is decorated with failure |
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43 information, either global or per-field , until it is valid) |
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44 |
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45 `Other`: |
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46 |
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47 * the SendMail controller (web/views/basecontrollers.py) is reponsible |
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48 for outgoing email notifications |
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49 |
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50 * the MailBugReport controller (web/views/basecontrollers.py) allows |
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51 to quickly have a `repotbug` feature in one's application |
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52 |
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53 Registration |
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54 ++++++++++++ |
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55 |
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56 All controllers (should) live in the 'controllers' namespace within |
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57 the global registry. |
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58 |
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59 API |
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60 +++ |
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61 |
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62 Most API details should be resolved by source code inspection, as the |
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63 various controllers have differing goals. |
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64 |
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65 `web/controller.py` contains the top-level abstract Controller class and |
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66 its (NotImplemented) entry point `publish(rset=None)` method. |
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67 |
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68 A handful of helpers are also provided there: |
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69 |
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70 * process_rql builds a result set from an rql query typically issued |
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71 from the browser (and available through _cw.form['rql']) |
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72 |
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73 * validate_cache will force cache validation handling with respect to |
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74 the HTTP Cache directives (that were typically originally issued |
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75 from a previous server -> client response); concrete Controller |
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76 implementations dealing with HTTP (thus, for instance, not the |
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77 SendMail controller) may very well call this in their publication |
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78 process. |
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79 |
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80 |
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81 .. _edit_controller: |
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82 |
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83 The `edit controller` |
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84 +++++++++++++++++++++ |
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85 |
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86 It can be found in (:mod:`cubicweb.web.views.editcontroller`). |
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87 |
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88 Editing control |
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89 ~~~~~~~~~~~~~~~~ |
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90 |
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91 Re-requisites: the parameters related to entities to edit are |
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92 specified as follows :: |
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93 |
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94 <field name>:<entity eid> |
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95 |
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96 where entity eid could be a letter in case of an entity to create. We |
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97 name those parameters as *qualified*. |
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98 |
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99 1. Retrieval of entities to edit by looking for the forms parameters |
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100 starting by `eid:` and also having a parameter `__type` associated |
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101 (also *qualified* by eid) |
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102 |
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103 2. For all the attributes and the relations of an entity to edit: |
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104 |
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105 1. search for a parameter `edits-<relation name>` or `edito-<relation name>` |
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106 qualified in the case of a relation where the entity is object |
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107 2. if found, the value returned is considered as the initial value |
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108 for this relaiton and we then look for the new value(s) in the parameter |
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109 <relation name> (qualified) |
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110 3. if the value returned is different from the initial value, an database update |
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111 request is done |
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112 |
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113 3. For each entity to edit: |
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114 |
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115 1. if a qualified parameter `__linkto` is specified, its value has to be |
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116 a string (or a list of string) such as: :: |
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117 |
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118 <relation type>:<eids>:<target> |
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119 |
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120 where <target> is either `subject` or `object` and each eid could be |
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121 separated from the others by a `_`. Target specifies if the *edited entity* |
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122 is subject or object of the relation and each relation specified will |
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123 be inserted. |
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124 |
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125 2. if a qualified parameter `__clone_eid` is specified for an entity, the |
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126 relations of the specified entity passed as value of this parameter are |
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127 copied on the edited entity. |
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128 |
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129 3. if a qualified parameter `__delete` is specified, its value must be |
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130 a string or a list of string such as follows: :: |
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131 |
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132 <ssubjects eids>:<relation type>:<objects eids> |
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133 |
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134 where each eid subject or object can be seperated from the other |
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135 by `_`. Each relation specified will be deleted. |
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136 |
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137 4. if a qualified parameter `__insert` is specified, its value should |
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138 follow the same pattern as `__delete`, but each relation specified is |
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139 inserted. |
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140 |
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141 4. If the parameters `__insert` and/or `__delete` are found not qualified, |
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142 they are interpreted as explained above (independantly from the number |
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143 of entities edited). |
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144 |
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145 5. If no entity is edited but the form contains the parameters `__linkto` |
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146 and `eid`, this one is interpreted by using the value specified for `eid` |
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147 to designate the entity on which to add the relations. |
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148 |
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149 |
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150 .. note:: |
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151 |
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152 * If the parameter `__action_delete` is found, all the entities specified |
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153 as to be edited will be deleted. |
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154 |
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155 * If the parameter `__action_cancel` is found, no action is completed. |
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156 |
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157 * If the parameter `__action_apply` is found, the editing is |
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158 applied normally but the redirection is done on the form (see |
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159 :ref:`RedirectionControl`). |
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160 |
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161 * The parameter `__method` is also supported as for the main template |
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162 |
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163 * If no entity is found to be edited and if there is no parameter |
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164 `__action_delete`, `__action_cancel`, `__linkto`, `__delete` or |
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165 `__insert`, an error is raised. |
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166 |
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167 * Using the parameter `__message` in the form will allow to use its value |
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168 as a message to provide the user once the editing is completed. |
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169 |
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170 |
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171 .. _RedirectionControl: |
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172 |
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173 Redirection control |
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174 ~~~~~~~~~~~~~~~~~~~ |
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175 Once editing is completed, there is still an issue left: where should we go |
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176 now? If nothing is specified, the controller will do his job but it does not |
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177 mean we will be happy with the result. We can control that by using the |
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178 following parameters: |
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179 |
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180 * `__redirectpath`: path of the URL (relative to the root URL of the site, |
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181 no form parameters |
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182 |
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183 * `__redirectparams`: forms parameters to add to the path |
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184 |
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185 * `__redirectrql`: redirection RQL request |
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186 |
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187 * `__redirectvid`: redirection view identifier |
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188 |
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189 * `__errorurl`: initial form URL, used for redirecting in case a validation |
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190 error is raised during editing. If this one is not specified, an error page |
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191 is displayed instead of going back to the form (which is, if necessary, |
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192 responsible for displaying the errors) |
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193 |
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194 * `__form_id`: initial view form identifier, used if `__action_apply` is |
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195 found |
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196 |
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197 In general we use either `__redirectpath` and `__redirectparams` or |
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198 `__redirectrql` and `__redirectvid`. |
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199 |
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