Questions tagged [qgis-variable]
"In QGIS, you can use variables to store useful recurrent values (e.g. the project’s title, or the user’s full name) that can be used in expressions. Variables can be defined at the application’s global level, project level, layer level, composition level, and composer’s item level." -QGIS User Manual
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Is there a way to export/import project variables?
I have a project with around 20 variables (for parameterizing font/line sizes, colors, etc. across multiple layers) in the Project Variables table (i.e. in Project>Settings>Variables/Project). I ...
3
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0
answers
67
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Create a virtual layer with a project variable defining the source layer(s) using QGIS
I would like to create a virtual layer where the source layer can easily be changed by editing the value of a project variable. Something like:
SELECT * FROM var('active_layer')
I found this post at ...
- 382
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2
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191
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Configuring QGIS Project using external config file
I have a large QGIS project file (let's call it the master project) and would like to use it for several customers.
Currently, I am creating copies of the master project for each customer and ...
- 8,196
2
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1
answer
85
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Extract an attribute from a created point and set it as a project variable
I am trying to create a QGIS modeler process by which the center point of the map on the desktop is used to query what County it falls in from a PostgreSQL data base and writes that county name as a ...
- 533
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213
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Adding variable to print layout using PyQGIS
I have a QGIS workspace (3.26) containing several vector and raster datasets. I plan to produce multiple print layouts from this workspace to display information such as the site location, predicted ...
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1
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108
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QGIS project variable in map composer template file?
I need to insert project variable into map composer file (.qpt) for showing specific legend item. The item is a layer constructed from a URL query that I need to dynamically change based on a project ...
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34
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QGIS variables as part of the interface
I've recently learned about how to use variables in QGIS. They are, however not that easily accessible as they are for example in Graphical Modeller, where they are part of the interface. Is it ...
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QGIS style overwrites layer variable
I set a layer variable with QgsExpressionContextUtils.setLayerVariable(layer, name, value) and then apply a style which is using the value of this variable (a color).
But when applying the style with ...
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Can't set label background nor callouts color to the the variable @symbol_color
Working with QGIS 3.22.8 you can set a data defined override for label color to match that of the associated feature using the variable @symbol_color, but it does not work for label background fill/...
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Is there a variable for the numerotation of the pages in the layout report workspace of QGIS?
I want to add the page numbers as it is possible with the layout atlas workplace, however I cannot find a similar variable to use in the report.
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86
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Set font with variable in layout
I'm using QGIS 3.16. I have a variable called Projet_font in my projet.
My problem is in the layout composer, it doesn't seem to be possible to use this variable to set the font text?
Here is as ...
- 1,544
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QGIS layout variables not refreshing when changed
I'm setting up over 100 layouts of different maps. I would like to control extents of layout map from one place, let's say via variable.
I tried a way using QGIS global variables but it seems to not ...
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Variable is not recognize in QGIS expression using overlay_nearest function
Context
I use an expression with Geometry Generator in QGIS 3.22 to connect each point with the nearest point that has the value of 2 for the attribute field called value. This works fine using this ...
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2
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86
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QGIS Group Layer Variables
QGIS Group Layers don't have properties, probably because of that there also doesn't exist the possibility to define variables for Group layers. I use Project variables and Layer variables but also ...
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How can I store a project or global variable that references an object PyQGIS? [closed]
I am working on an expression that creates an object, Specifically, I am creating a connection to a database (cursor), which remains available until it is closed.
I need the reference to the object to ...
- 1,254
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2
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300
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Indexing from first row of attribute table with Python
I'm just trying to extract the variable value of the 7th column of the first row in a vector layer. I'm not sure how to index the table exactly though. I included the lines I wrote, which I imagine ...
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How variabilizing a part of the name of the data table used by QGIS ? I would like to use the same QGIS project for each year I'm studying
I created a map and a page layout for year 2018:
It relies on data of the table temp_desendettement_communes_2018 (from a PostGIS database).
I wish using the same QGIS project for other years, and ...
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1
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Forcing choice for default value during data entry
Let's assume you have to perform different field surveys for different projects. For example, you have to log all sightings of birds for different projects.
During data entry of the bird sightings I ...
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2
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1
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334
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Defining an array as a variable in QGIS
I want to use array_first(@myArray) to get the first value of myArray in a data defined box.
myArray is defined in the project variables, but I can't find the correct syntax. I tried :
(1, 2, 'abc')
[...
- 1,194
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1
answer
925
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How to Access the Current Value of the Scale Factor of a Map as a Variable (eg $map_scale) in Print Layouts in QGIS
Does anybody know how to access the current value of the scale factor of a map as a variable (eg $map_scale) in print layouts in QGIS?
I'd love to put the scale factor in my maps...
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138
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Adding different strings to legend title in QGIS layer composer depending on which layer is active
My QGIS project includes three layers representing catchment areas for playgrounds. Depending on the age of the children, the catchment areas are either 200 m (catch_area_200m.shp), 400 m (...
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1
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Is there a way to edit project variables with modeller in QGIS?
Is there some way to set/edit user defined project variables with a model or a calculator so their values can be read by all the layouts and reports in a project? I want to calculate a project ...
- 533
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0
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46
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Defining variables by selection
I'm working on a valve isolation project for a natural gas application. I'm a design engineer foremost, but like to play with programming and GIS applications fairly often. I've got a bit of ...
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3
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Using the regexp_substr function in QGIS to get the first letter after white space
I am looking to get the first letter and second letter (after white space) in the QGIS variable @user_full_name to provide me with the initials of the QGIS user that has created a project.
For ...
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133
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Set a WMS URL in QGIS using project variables
I would to know if it is possible to set a WMS url in which I would use project variables as parameters?
Let's say I have:
QGIS project variable : my_variable = some_query
WMS url : https://wxs....
- 456
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212
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QGIS 3.6: variable functions, confusing explanation
The documentation (https://docs.qgis.org/3.4/en/docs/user_manual/working_with_vector/expression.html#id31) says:
To use these functions in an expression, they should be preceded by @ character (e....
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562
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QGIS 3 - Variables in rule-based rendering?
I'll try and lay this out clearly, I have most of it covered, but there's a very specific thing I'm looking for in the rules - whether or not it can be done and if so, how?
Key things I have done and/...
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57
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Suggestions on how I can depict numerous cell towers with different ranges?
I am trying to make buffers dependent on cell tower ranges. Does anyone have any suggestion on how to insert distance buffers of various that are dependent on attribute values in one layer?
I am ...
user126405
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142
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How to make QGIS model result to be a variable?
My model's temporary result is a point layer (one feature) and I need a value from one of its fields because I want to use it in the same model to select a feature on another layer.
So for example, ...
- 1,033
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QgsVariableEditorWidget does not save changes
I would like to edit the variables of a composer item in QGIS 2.18.x.
The widget itself is working so far. In my example, I am selecting a QgsComposerLabel called "Plankopf" to show its variables.
...
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5
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493
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increment column value with an integer when it is a duplicate
I have a layer with around 1000 lines. Some Name are repeated several times and I wish to have every name unique. Thus I try in the field calculator to add an integer at the end of the name only when ...
6
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1
answer
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Getting active PostgreSQL connection's username as variable in QGIS?
Is it possible to get login username from a current PostgreSQL layer connection in QGIS?
My goal is to automatically populate new objects in a layer with an editor login username (not @...
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Global variables in QGIS mixed on some computers
I create and set some global variables in my QGIS plugin as below:
QgsExpressionContextUtils.setGlobalVariable('variable_name', 'some_value')
The name is unique and specific, so different from any ...
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322
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QGIS atlas with chart
I use the the atlas in QGIS for a while, and I use a variable from the atlas to filter labels, construct geometries, etc. But the atlas variables aren't everywhere in QGIS and I can't make a real ...
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3
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QGIS Query Editor define variable
I am relatively new to QGIS. I use conditional formatting for various problems. In the qgis query editor, I would like to define a string variable for further usage, so I wouldn't have to retype the ...
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On QGIS Composer how to filter the atlas coverage layer using a project variable (rather than just a value)?
A QGIS Composer atlas can be generated from a subset of the coverage layer features using the coverage layer filter control. I can filter for coverage layer features by comparing an attribute of the ...
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How to get layer variables using QGIS Python APIs?
How can I access the layer variables defined by the user from QGIS Python APIs?
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2k
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QGIS using project variables in filter queries
In QGIS 2.14.11 LTR I have to apply the same (or similiar) filter query to various layers. I have the road name to filter for in a project variable and try to apply the following query:
"road_name" = ...
- 14.6k