workbench-en.a4

Customizing DBDoc Model Reporting Templates
That is, the model contains two schemata, Airlines and Airports.
Data Dictionaries
It is important to understand the relationship between sections and data dictionaries in more detail. In a data dictionary the key for a
variable is the variable name, a marker. The variable value is the variable's data. The entry for a section in a data dictionary is different.
For a section entry in a data dictionary, the key is the section name, the marker. However, the value associated with the key
is a list of data dictionaries. In MySQL Workbench each section is usually associated with a data dictionary. You can think of a
section as activating its associated dictionary (or dictionaries).
When a template is processed, data dictionaries are loaded in a hierarchical pattern, forming a tree of data dictionaries. This is illustrated
by the following table:
Data Dictionary
MAIN
SCHEMATA
TABLES
COLUMNS_LISTING
REL_LISTING
INDICES_LISTING
Loads Data Dictionary
SCHEMATA
TABLES, COLUMNS (Detailed is true), FOREIGN_KEYS (Detailed is true),
INDICES (Detailed is true)
REL_LISTING, INDICES_LISTING, COLUMNS_LISTING, TA-
BLE_COMMENT_LISTING, DDL_LISTING
COLUMNS (Detailed is false)
REL (Detailed is false)
INDICES (Detailed is false)
The root of the tree is the main dictionary. Additional dictionaries are then loaded from the root to form the dictionary tree.
Note
If a template has no sections in it, then any variables used in the template will be looked up in the main dictionary. If a
variable is not found in the main dictionary (which can be thought of as associated with the default, or main, section)
then no data will be generated in the output file for that marker.
Evaluation of variables
The tree structure of the data dictionaries is important when it comes to evaluation of variables. As variables are defined in data
dictionaries, their associated value only has meaning when that particular data dictionary is active, and that means when the section
associated with that data dictionary is active. When a variable lookup occurs, the system will check the data dictionary associated
with the current section. If the variable value can be found there the replacement is made. However, if the variable's value is not
found in the current data dictionary then the parent data dictionary will be checked for the variable's value and so on up the tree until
the main data dictionary, or root, is reached.
This can best be illustrated by an example. Assume we want to display the names of all columns in a model. Consider the following
template as an attempt to achieve this:
Report
------
Column Name: {{COLUMN_NAME}}
This template will produce no output, even for a model that contains many columns. In this example the only data dictionary active
is the main dictionary. COLUMN_NAME however is stored in the COLUMNS data dictionary, which is associated with the COLUMNS
section.
With this knowledge the template can be improved as follows:
Report
------
{{#COLUMNS}}
Column Name: {{COLUMN_NAME}}
{{/COLUMNS}}
This still does not produce output. Referring to the table Data Dictionary Hierarchy Tree explains why. The COLUMNS data dictionary
has the parent dictionary COLUMNS_LISTING. COLUMNS_LISTING has the parent TABLES, which has the parent
SCHEMATA, whose parent is the main dictionary. Remember in order for a dictionary to be involved in variable lookup, its associated
section must currently be active.
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