Thymeleaf concatenation preprocessing: - spring

Question

I hope someone can help me with my problem with Thymeleaf.
The case is that I need to do preprocessing with thymeleaf, the first one does it correctly, but inside that first preprocessing I need to get another field from the model, but when I add the field preprocessinf inside another preprocessing it gives me a type error
Could not parse as expression: "$ {rules ["
If I do this, it works fine
rules[__${row.index}__].propertiesValues[]
Failure to insert the other preprocessing
rules[__${row.index}__].propertiesValues[__${rules[__${row.index}__].bookingRuleDescriptor.propertyDescriptors[__${iter.index}__].name}__]
I hope you can help me.
Thank you!!

Answer 1

There is only one preprocessing pass. You get that error because of the mismatched __. For example, the first time it tries to preprocess:
propertiesValues[__${rules[__${row.index}__]
The expression it tries to evaluate is __${rules[__, which is not a valid thymeleaf expression.
The options you have are:
1) If this expression is not being used in a th:field, you shouldn't be doing preprocessing anyways. You can simply use:
${rules[row.index].propertiesValues[rules[row.index].bookingRuleDescriptor.propertyDescriptors[iter.index].name]}
2) If you are using this in a th:field, you'll have to use th:with to evaluate some of your expressions before hand. Something like:
<th:block th:with="i=${row.index}, j=${rules[row.index].bookingRuleDescriptor.propertyDescriptors[iter.index].name}">
<input type="text" th:field="*{rules[__${i}__].propertiesValues['__${j}__']}" />
</th:block>