Maybe it would be good to have a merge of the two ideas. Have a set of pre-built rules (non-python) that you can supply in the fields tab with the ability to also supply a Python file which has more complex rules e.g<div>
<br></div><div>if field1 == "Hello WOrld" and field2 < field3 then error</div><div><br></div><div>etc </div><div><br></div><div>Thoughts?</div><div><br></div><div>P.S </div><div>>> I cannot be sure that anyone loading my qml file has the python file available in the same path as I do</div>
<div>Normally I would store the python file in the same folder as the project file and ship it with the project but I get what you mean.</div><div><br></div><div>- Nathan<br><br><div class="gmail_quote">On Tue, Dec 20, 2011 at 10:10 PM, <span dir="ltr"><<a href="mailto:bernhard.stroebl@jena.de">bernhard.stroebl@jena.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Nathan,<br>
<br>
I do like your idea, it in fact would reduce the need for custom Uis. How about saving the check as part of the project or qml file similar to the edit-widget option in the layer properties. Because for my feeling that would be the place where it belongs and I cannot be sure that anyone loading my qml file has the python file available in the same path as I do.<br>
Probably there is only a limited number of checks which cover the majority of use cases e.g.<br>
- NOT NULL<br>
- range (for Numbers)<br>
- range (for dates)<br>
- max length (for strings)<br>
- contains regex/string (for strings)<br>
Multiple rules could be applied to any field in the fields tab of the layer properties. For special cases you would still need a custom Ui, though.<br>
<br>
just my two cents<br>
<br>
Bernhard<br>
<br>
<br>
<br>
Am <a href="tel:20.12.2011%2012" value="+12012201112" target="_blank">20.12.2011 12</a>:41, schrieb Nathan Woodrow:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
Hi all,<br>
<br>
I have been working on this idea over the last couple days which I think<br>
would be cool/handy to have in QGIS and I would be interested to get some<br>
feedback with what people think.<br>
<br>
The general idea is to add a form of field validation to the built-in<br>
attribute forms. The use case for this is pretty clear I think, being able<br>
to let the user/admin of any layer define validation rules to check against<br>
the data entered on the attribute form when the user presses OK providing<br>
instant feedback. I normally do this on my PostGIS tables but you don't<br>
get errors until you try and commit the data and even then it's a simple<br>
"there is a error", if you have added more then 1 item you have to check<br>
each one to work out what is wrong, and this method only applies to a<br>
PostGIS layer. The idea I have been drafting would work on any layer, as<br>
it's at the QGIS level vs at the datasource level.<br>
<br>
My idea is to use simple a simple Python file with basic functions that<br>
will be called for each field in the attribute form that is editable. I'm<br>
a big fan of convention over configuration so my idea uses conventions to<br>
define what functions are used to validate what fields. The function will<br>
return False and an error message that can be shown to the user if<br>
something is wrong.<br>
<br>
The functions use the following syntax: validate{FieldName} or<br>
validate{FieldIndex} for naming (plus some other styles) e.g<br>
<br>
def validateName():<br>
if value == "":<br>
return (False,"Name can't be NULL")<br>
return True<br>
<br>
You would place the function in a python file e.g PeopleRules.py and then<br>
tell QGIS to use this file to look for validation rules, pretty much the<br>
same as we do now for having custom Python forms.<br>
<br>
Overview of logic:<br>
<br></div></div>
1. Define Python file with rules<br>
2. Tell QGIS to use the rules file for the layer.<br>
3. Open attribute form<br>
4. Edit some values<br>
5. Press OK<br>
6. QGIS calls each function in the rules file to validate each field<div class="im"><br>
that is defined with a rule<br></div>
7. If there are errors: cancel the accept() action and show the errors.<div class="im"><br>
If there are no errors go though like normal.<br>
<br>
My thoughts for using Python are:<br>
<br></div>
- Easy to read and write<br>
- Not limited to what we have in QgsExpression and easier to expand.<br>
- Can add documentation to validation rules.<br>
- Can add more complex validation rules e.g. regex, parsing, database<div class="im"><br>
checks etc<br>
<br>
My overall goal with this is to reduce the need to create custom Python Qt<br>
forms when doing data entry, and doing validation is one of the reasons I<br>
tend to make custom Python Qt forms but then you loose the ease of QGIS<br>
doing most of the form work for you.<br>
<br>
I have attached two files which have a example of what the idea is.<br>
fieldChecks.py is an example rules file with comments to explain each<br>
section, runMe.py has the logic for reading and executing the rules for<br>
each field. Run: python runMe.py to see the running logic and output.<br>
<br>
What love to get peoples thoughts about this, users and devs a like.<br>
<br>
- Nathan<br>
<br>
<br></div>
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