prepare vrt file in background thread.

app/corpora/views.py

+from app.utils import background_prepare_corpus_file
 from flask import (abort, current_app, flash, redirect, request,
                    render_template, url_for, send_from_directory)
 from flask_login import current_user, login_required
@@ -115,6 +116,11 @@ def add_corpus_file(corpus_id):
                                  title=add_corpus_file_form.title.data)
         db.session.add(corpus_file)
         db.session.commit()
+        background_thread = threading.Thread(
+            args=(current_app._get_current_object(), corpus_file.id),
+            target=background_prepare_corpus_file
+        )
+        background_thread.start()
         flash('Corpus file added!')
         return redirect(url_for('corpora.corpus', corpus_id=corpus_id))
     return render_template('corpora/add_corpus_file.html.j2',

app/jobs/views.py

@@ -24,7 +24,8 @@ def delete_job(job_id):
     if not (job.creator == current_user or current_user.is_administrator()):
         abort(403)
     delete_thread = threading.Thread(target=background_delete_job,
-                                     args=(current_app, job_id))
+                                     args=(current_app._get_current_object(),
+                                           job_id))
     delete_thread.start()
     flash('Job has been deleted!')
     return redirect(url_for('main.dashboard'))

app/models.py

+from datetime import datetime
 from flask import current_app
 from flask_login import UserMixin, AnonymousUserMixin
 from itsdangerous import BadSignature, TimedJSONWebSignatureSerializer
 from werkzeug.security import generate_password_hash, check_password_hash
-import xml.etree.ElementTree as ET
 from . import db
 from . import login_manager
-from datetime import datetime
 import os
 import shutil
 import logging
+import xml.etree.ElementTree as ET
 
 
 class Permission:
@@ -411,18 +411,6 @@ class CorpusFile(db.Model):
     title = db.Column(db.String(64))
     corpus_id = db.Column(db.Integer, db.ForeignKey('corpora.id'))
 
-    def __init__(self, **kwargs):
-        super(CorpusFile, self).__init__(**kwargs)
-        file = os.path.join(current_app.config['OPAQUE_STORAGE_DIRECTORY'],
-                            self.dir,
-                            self.filename)
-        element_tree = ET.parse(file)
-        text_node = element_tree.find('text')
-        text_node.set('author', self.author)
-        text_node.set('publishing_year', str(self.publishing_year))
-        text_node.set('title', self.title)
-        element_tree.write(file)
-
     def delete(self):
         logger = logging.getLogger(__name__)
         logger.warning('Called CorpusFile.delete')
@@ -437,6 +425,17 @@ class CorpusFile(db.Model):
         db.session.delete(self)
         db.session.commit()
 
+    def insert_metadata(self):
+        file = os.path.join(current_app.config['OPAQUE_STORAGE_DIRECTORY'],
+                            self.dir,
+                            self.filename)
+        element_tree = ET.parse(file)
+        text_node = element_tree.find('text')
+        text_node.set('author', self.author)
+        text_node.set('publishing_year', str(self.publishing_year))
+        text_node.set('title', self.title)
+        element_tree.write(file)
+
 
 class Corpus(db.Model):
     """

app/utils.py

-from .models import Job, User, Corpus, CorpusFile
 from . import db
+from .models import Job, User, Corpus, CorpusFile
 import logging
 
 
@@ -69,3 +69,4 @@ def background_delete_corpus(app, corpus_id):
 def background_prepare_corpus_file(app, corpus_file_id):
     with app.app_context():
         corpus_file = CorpusFile.query.filter_by(id=corpus_file_id).first()
+        corpus_file.insert_metadata()