BLOB Support in Forms and Reports in Oracle Apex
Understanding BLOB Support in Forms and Reports
Displaying BLOB Images in Oracle APEX Reports
Oracle APEX simplifies the process of displaying images stored as BLOBs in reports. Developers can easily render these images by including the necessary columns in the report query. This approach allows for a dynamic and visually rich report experience, where images stored as BLOBs are seamlessly displayed, enhancing the overall user interface.
Displaying images stored as BLOBs in Oracle APEX reports is straightforward and involves adjusting your report query and settings. Follow these simple steps to show BLOB images in your report:
Steps to Display a BLOB Image in a Report:
-
Access Page Designer:
- Open the page containing the report in Page Designer.
-
Modify the Source:
- If your report's source is based on a Table/View, change it to an SQL Query. This allows more flexibility and control over the query.
-
Add a Numeric Column:
- Add a new numeric column to your SQL query to check the image file size. If the length is zero, it means the BLOB is empty (NULL), and no image will be shown.
Example SQL Query:
SELECT COLUMN_N, DBMS_LOB.GETLENGTH([BLOB_COLUMN]) AS IMAGE FROM BLOB_TEST_TABLE
-
Configure Image Display:
- Set the Type of the new column to Display Image. This will tell Oracle APEX to render the BLOB content as an image.
-
BLOB Attributes Configuration:
- Table Name: Enter the name of the table storing the BLOB content.
- BLOB Column: Select the column that contains the BLOB data.
- Primary Key Column(s): Choose the primary key column(s). If there are multiple columns in the primary key, select the ROWID column.
- Optional Columns: You can also choose optional columns such as Mime Type, Filename, or Last Updated if needed.
Note: If the BLOB is not an image, it may not display correctly, depending on the browser and file type.
-
Image Display Behavior:
- The image will display with its original dimensions (height and width in pixels).
Customize Image Size with CSS:
To control the size of the displayed images in the report, you can add custom CSS. Here’s how to do it:
-
Assign a Static ID:
- In Advanced settings, give your image column a Static ID (e.g.,
my_report_image_column
).
- In Advanced settings, give your image column a Static ID (e.g.,
-
Add CSS Code:
- Go to CSS and add the following code in the Inline Attribute section. For example, to set the image height to 25 pixels:
td[headers="my_report_image_column"] img { height: 25px; }
-
Save Changes:
- Click Save or Save and Run Page to apply the changes.
With these steps, you can easily display and customize BLOB images in your Oracle APEX reports, providing a better user experience and more control over the visual presentation.
Managing BLOBs Programmatically in Oracle APEX
Beyond the declarative approach, Oracle APEX offers programmatic options for working with BLOBs. Developers can use the APEX_UTIL.GET_BLOB_FILE_SRC
function to retrieve the source of a BLOB file. This allows for more granular control over how BLOB data is retrieved and displayed within reports or across different parts of the application.
This flexibility enables the creation of highly interactive reports and applications that can handle and present BLOB content efficiently, making it easier to manage files and images within your Oracle APEX applications.
No comments