sorting features and values in the mobile app (#513)

* sorting features and values in the mobile app

* fix broken links

* Update src/gis/search_data.md

---------

Co-authored-by: Tomas Mizera <tomas.mizera@lutraconsulting.co.uk>

Author: alex-cit

src/field/layers/index.md

@@ -5,7 +5,7 @@ The **Layers** button is located in the bottom navigation panel.
 
 It provides the overview of layers and features in your <MainPlatformNameLink /> project in <MobileAppName />, as well as the option to turn the visibility of specific layers on/off or to see a layer's legend.
 
-![Layers in Mergin Maps mobile app](../mobile-app-ui/mobile-app-layers.jpg "Layers in Mergin Maps mobile app")
+![Layers in Mergin Maps mobile app](../../layer/non-spatial-data/mobile-app-non-spatial-layers.jpg "Layers in Mergin Maps mobile app")
 
 ## Layers visibility
 
@@ -16,8 +16,26 @@ The visibility of layers on the map can be easily turned on and off by toggling
 ![Mergin Maps mobile app Layers visibility](./mobile-app-layers-off.jpg "Mergin Maps mobile app Layers visibility")
 
 ## Layers legend and features
-Select a layer in the **Layers** panel to browse features and [search for attributes values](../../gis/search_data/#searching-for-values-in-mergin-maps-mobile-app). Tap on the record to zoom to the feature on the map and display its form.
+Select a layer in the **Layers** panel to browse features and [search for attributes values](#browsing-features). Tap on the record to zoom to the feature on the map and display its form.
 
 Swipe right or tap **Layer info** to see the layer's legend and to toggle on/off its visibility on the map.
 
 ![Mergin Maps mobile app Layers legend and features](./mobile-app-layers.jpg "Layers legend and features")
+
+## Browsing features
+Attribute data can be browsed in the <MobileAppNameShort /> by tapping **Layers**. 
+
+In the **Layers** window, choose a layer or a table from the list to open the list of features.
+
+![Layers overview in Mergin Maps mobile app](../mobile-app-ui/mobile-app-layers.jpg "Layers overview in Mergin Maps mobile app")
+
+Here, you can browse the features. The search bar can be used to shortlist matching records. The search looks up for a match in all searchable attributes values and is not case sensitive.
+
+:::tip Sorting features and searching for field values
+The way how features are sorted in the <MobileAppNameShort /> can be affected by [settings in the QGIS project](../../gis/search_data/).
+:::
+
+Tap on the record to zoom to the feature on the map and display its form.
+
+![Mergin Maps mobile app browse data](./mobile-app-search-data.jpg "Mergin Maps mobile app browse data")
+

src/gis/mobile-app-search-data.jpg renamed to src/field/layers/mobile-app-search-data.jpg

@@ -1,45 +1,78 @@
-# Searching for Values in Attribute Fields
+# Sorting and Search Setup
 [[toc]]
 
-In <MobileAppName />, you can search for the content of fields in spatial layers and non-spatial tables, as well as searching values from multiple fields.
+There are some settings related to sorting, searching and browsing features in <MobileAppName />  that can be done in the QGIS project, such as define the order of features and values or include/exclude layers and fields from the search.
+
+Working with layers in the <MobileAppNameShort />, including browsing features and values, is described in [Layers in <MobileAppName />](../field/layers/).
+
+
+## Sorting features and value list
+The <MobileAppNameShort /> follows the sorting of features in the attribute table and of values in the value relation widget as set in the QGIS project.
+
+###  Order value list by value
+The [Value relation](../layer/form-widgets/#value-relation) widget has the option *Order by value*. When checked, values in the drop-down list will be listed in alphabetical or numerical order. 
+
+![QGIS Value relation order by value](./qgis-order-by-value-value-relation.jpg "QGIS Value relation order by value")
+
+This setting is also followed by the <MobileAppNameShort />. 
+
+On the left, you can see the default list of options in the drop-down menu. On the right, the option *Order by value* is used and observed by the <MobileAppNameShort />.
+![QGIS Value relation order by value](./mobile-value-relation-sorted.jpg "QGIS Value relation order by value")
+
+
+###  Sorting features by field value
+By default, the <MobileAppNameShort /> orders features in a layer based on their `Feature ID`. The order of features can be defined in the Attribute table in QGIS.
+
+Simple sorting based on ascending or descending value of the attributes can be used:
+
+1. Open your project in QGIS
+2. Right-click on a survey layer and open the **Attribute table**
+3. In the **Attribute table**, click on the name of a field to sort the features according to the field values.
+   Here, we use the `update_at` field to sort features by the last update. The feature that was updated last will be the first in the list.
+   ![QGIS Attribute table order by value](./qgis-sorting-attribute-table-updated-at.jpg "QGIS Attribute table order by value")
+4. Save and synchronise the project.
+
+In the <MobileAppNameShort />, features in a layer can be browsed by tapping the **Layers** button and selecting the layer from the list.
+![Mobile app sort features by value](./mobile-layers.jpg "Mobile app sort features by value")
+
+Features in this layer are sorted by the same field value as was defined in the QGIS project. So, instead of the default sorting by the `Feature ID`, the features are ordered by the date and time of their last update.
+![Mobile app sort features by value](./mobile-sort-updated-at.jpg "Mobile app sort features by value")
+
+###  Sorting features by expression
+Similarly, an expression can be used to sort features in the Attribute table and subsequently in the <MobileAppNameShort />.
+
+1. Open your project in QGIS
+2. Right-click on a survey layer and open the **Attribute table**
+3. Right-click on a field name that you want to use for sorting features and use the **Sort...** option
+   ![Mobile app sort features by value](./qgis-attribute-table-sort.jpg "Mobile app sort features by value")
+4. Enter the expression you want to use to sort this field.
+   Here, we use `length( "notes" )` to sort features based on the length of the text in the `notes` field.
+   ![QGIS sorting features by text length](./qgis-attribute-table-sort-expression.jpg "QGIS sorting features by text length")
+   ![QGIS features sorted by text length](./qgis-attribute-table-sorted-by-length.jpg "QGIS features sorted by text length")
+5. Save and synchronise the project.
+
+When browsing features in the <MobileAppNameShort />, they will be sorted by the text length.
+![Mobile app sort features by value](./mobile-sorting-by-text-lentgh.jpg "Mobile app sort features by value")
+
 
 ## Setting identifiable layers in QGIS project
-To be able to browse the attributes of a layer, it needs to be set as *Identifiable* in your <QGISHelp ver="3.22" link="user_manual/introduction/qgis_configuration.html?highlight=properties#data-sources-properties" text="QGIS project" />.
+To be able to browse the attributes of a layer, it needs be *Identifiable* in your <QGISHelp ver="latest" link="user_manual/introduction/qgis_configuration.html?highlight=properties#data-sources-properties" text="QGIS project" />. Layers are *identifiable* by default.
+
+If you define a layer as **not identifiable**, you won't be able to tap it in the <MobileAppNameShort /> or use the **Identify tool** in QGIS to see its attribute form. This may be useful for layers that are only used as background layers.
 
 1. Open your QGIS project
 2. In the Menu > Project > Properties click on **Data Sources**
 3. Check and uncheck layers in the **Identifiable** column to define which layers you want to be able to browse in your project.
 
 ![QGIS identifiable data sources](./qgis_data_sources.jpg "QGIS identifiable data sources")
 
-:::warning
-If you define a layer as **not identifiable**, you won't be able to tap it in <MobileAppName /> or use the **Identify tool** in QGIS to see its attribute form.
-:::
 
 ## Exclude a field from the search
 By default, all attributes are searchable. You can exclude a field from the search in the **Layer properties**. 
-1. Navigate to the **Fields** tab
-2. Check the **Not searchable** option in the **Configuration** column
-![QGIS Not searchable field](./not_searchable.jpg "QGIS Not searchable field")
 
-:::warning
 If a field is marked in a field configuration as **Not searchable**, it will be omitted from the search. There will be no search results, even if you search for a specific existing value of this field.
-:::
-
-## Searching for values in Mergin Maps mobile app
-Attribute data can be browsed in <MobileAppName /> by tapping **Layers**. 
-
-In the **Layers** window, choose a layer or a table from the list to open the attribute table.
 
-![Layers overview in Mergin Maps mobile app](./mobile-app-layers.jpg "Layers overview in Mergin Maps mobile app")
-
-Here, you can browse the features. The search bar can be used to shortlist matching records. 
-
-Tap on the record to zoom to the feature on the map and display its form.
-
-![Mergin Maps mobile app browse data](./mobile-app-search-data.jpg "Mergin Maps mobile app browse data")
-
-:::tip
-The search looks up for a match in all searchable attributes values and is not case sensitive.
-:::
+1. Navigate to the **Fields** tab
+2. Check the **Not searchable** option in the **Configuration** column
+![QGIS Not searchable field](./not_searchable.jpg "QGIS Not searchable field")
 

src/gis/mobile-app-search-data.xcf renamed to src/field/layers/mobile-app-search-data.xcf

@@ -17,5 +17,5 @@ Tap the [**Layers**](../../field/layers/) button to open the list of layers, inc
 
 ![Layers in Mergin Maps mobile app](./mobile-app-non-spatial-layers.jpg "Layers in Mergin Maps mobile app")
 
-Tap on a layer to open its attributes table where you can browse the data and [search for values](../../gis/search_data/#searching-for-values-in-mergin-maps-mobile-app). It is also possible to [add and edit](../../field/mobile-features/#add-non-spatial-features) entries in the table.
+Tap on a layer to open its attributes table where you can browse the data and [search for values](../../field/layers/#browsing-features). It is also possible to [add and edit](../../field/mobile-features/#add-non-spatial-features) entries in the table.