All the code, parameters and data structure information of the project is stored in the admin.sqlite SQLite database located in the project folder. This information we call the metadata.
The project metadata can be exported to a zip file in the Application Builder by clicking the Export button.
This file contains the following information:
Information about project data structure (information about DB tables, fields, indexes defined in the project items), code and settings that is stored in the admin.sqlite database.
Files from the following folders:
css
js
static/css
static/js
static/img
reports (ods files of project report templates)
utils (this folder may contain python libraries or files used in the project)
The metadata file can be imported to another project.
The web application while importing the metadata performs the following operations:
sets the under_maintenance flag so that incoming requests are not processed by the application. When receiving the response to theses requests the client application shows the message “Web site currently under maintenance”. Web applications that run in parallel processes upon receiving requests check whether the under_maintenance flag is set and, if so, also do not process requests.
unzips the metadata file to the temporary folder in the project directory
checks the data integrity - items with the same ID in the current project and imported metadata must have the same type and the same table_name attribute if one is specified for an item
analyzes the metadata to generate sql queries to update the project database structure and records of the admin.sqlite database.
if the Import delay attribute in the project Parameters is set, waits the number of seconds set in the attribute, otherwise waits for 5 minutes or until all previous request to the server will be processed.
updates the project database and modifies the records of the admin.sqlite, see bellow
copies files from the temporary folder to the project folder
reloads the task tree
writes the import log file to the logs folder and sends the import log to the Application builder to be displayed
deletes the temporary folder
removes the under_maintenance flag
increases the build flag, so web applications that run in parallel processes and monitor this flag reload their task tree
The way the the project database is updated depends on the type of the project database.
Updating databases that support DDL statement rollback (Postgress, Firebird, MSSQL)
creates the connection to the project database
starts to execute sql statements to update the project database.
if an error occurs while updating the project database, rollbacks the changes, and goes to the step 9.
after the project database has been updated, makes a copy of the admin.sqlite file and starts modifying the admin.sqlite database
if an error occurs while modifying the records of admin.sqlite, restores admin.sqlite from the copy, rollbacks the changes to the project database and goes to the step 9.
commits the changes, deletes the copy of the admin.sqlite, closes connection and goes to the step 7.
Updating databases that do not support DDL statement rollback (MySql, Oracle)
creates the connection to the project database
starts to execute sql statements to update the project database.
if an error occurs while updating the project database writes error to the import log and continues until all statements will be processed
commits the changes
starts modifying the admin.sqlite database
closes connection and goes to the step 7.
Due to the fact that all items and fields of Jam.py projects have a unique ID attribute, Jam.py very accurately generates sql queries to modify the project database.
While generating sql queries the application currently compares only metadata in the current and imported project. The errors can occur when the application, for example, tries to adds to a table a field that doesn’t exist in the current project metadata but exists in the database table, you created this field outside of Application Builder. This situations can be corrected using Manual mode in Application Builder, see Database, and changing the database.
If you won’t change tables, field and indexes of production database, there will be no problems. Carry out development on the development project and then import its metadata into production.
Note
For the databases that do not support DDL statement rollback (MySql, Oracle) we recommend that you make a backup of the project database and admin.sqlite before performing the import.
Note
For SQLite database, Jam.py doesn’t support importing of metadata into an existing project (project with tables in the database). You can only import metadata into a new project.