When you need to render the label value for a specific field without rendering the entire HTML label element (e. g. to use it for a placeholder) do it by using the
label form variable like described here: Symfony2: How to Get the Label for a Specific Form Field in Twig.
If you are using the Gedmo SoftDeletable Doctrine extension for entities that have some unique index columns, you will probably encounter a MySQL error when trying to add new entity with the same values as one previously deleted:
SQLSTATE: Integrity constraint violation: 1062 Duplicate entry ... for key …
Find out how to avoid this by reading this post: Symfony2: Gedmo SoftDeletable Doctrine Entities with Unique Index Columns.
Sometimes you need to check if a field or even the entire form has errors before rendering them (e.g. when adding an errors container). Find out how by reading the post I wrote here: Symfony2: How to Check If a Form Field Has Errors in Twig.