[erdiag.git] / README.md

# erdiag: Entity-Relationship Diagrams Generator

Inspired by [this repository](https://code.google.com/archive/p/merisier/).

This parser reads ER diagrams definition files, and produces two types of diagrams + SQL code.
[Graphviz](https://www.graphviz.org/) is used on server side to translate parsed graph descriptions into SVG objects.

*TODO list:* functional integrity constraints (CIF), inter-relations constraints (or, and, xor...), inheritance with the right symbol (triangle).

*Note:* temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method.

-----

An entity is defined as follow

	[Entity]
	#attr1 (*)
	attr2 (*)

with (\*) = optional SQL indications, and # denoting a (part of) a key.

A relationship is defined in this way

	{Relation}
	Entity C1
	Entity2 C2
	--
	attr1 (*)
	attr2 (*)

where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2).
Defining relationships with more than two attributes is easy: just add entities.
Cardinality dictionary:
 * \* = 0..n
 * \+ = 1..n
 * 1 = 1..1
 * ? = 0..1

Special cardinalities are also available to indicate relative identification: `?R` and `1R`.

To mark a weak entity, just surround its name by extra-brackets

	[[WeakEntity]]

In the same way, a weak relation can be written

	{{WeakRelation}}

The syntax for these two last is then the same as in the non-weak versions.

To indicate an inheritance relation, proceed as follow

	is_a
	Animal Cat Fish
	Planet Mars Venus

Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example\_\*.svg)

Note that the "drawMcd" method can take a second argument, which indicates the type of graph.
 * "bubble" draws the standard graph, as seen [here](https://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model#/media/File:ER_Diagram_MMORPG.png) for example
 * "compact" (default) use the same box for an entity and its attributes
Commit	Line	Data
	1	# erdiag: Entity-Relationship Diagrams Generator
	2
	3	Inspired by [this repository](https://code.google.com/archive/p/merisier/).
	4
	5	This parser reads ER diagrams definition files, and produces two types of diagrams + SQL code.
	6	[Graphviz](https://www.graphviz.org/) is used on server side to translate parsed graph descriptions into SVG objects.
	7
	8	TODO list: functional integrity constraints (CIF), inter-relations constraints (or, and, xor...), inheritance with the right symbol (triangle).
	9
	10	Note: temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method.
	11
	12	-----
	13
	14	An entity is defined as follow
	15
	16	[Entity]
	17	#attr1 (*)
	18	attr2 (*)
	19
	20	with (\*) = optional SQL indications, and # denoting a (part of) a key.
	21
	22	A relationship is defined in this way
	23
	24	{Relation}
	25	Entity C1
	26	Entity2 C2
	27	--
	28	attr1 (*)
	29	attr2 (*)
	30
	31	where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2).
	32	Defining relationships with more than two attributes is easy: just add entities.
	33	Cardinality dictionary:
	34	* \* = 0..n
	35	* \+ = 1..n
	36	* 1 = 1..1
	37	* ? = 0..1
	38
	39	Special cardinalities are also available to indicate relative identification: `?R` and `1R`.
	40
	41	To mark a weak entity, just surround its name by extra-brackets
	42
	43	[[WeakEntity]]
	44
	45	In the same way, a weak relation can be written
	46
	47	{{WeakRelation}}
	48
	49	The syntax for these two last is then the same as in the non-weak versions.
	50
	51	To indicate an inheritance relation, proceed as follow
	52
	53	is_a
	54	Animal Cat Fish
	55	Planet Mars Venus
	56
	57	Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example\_\*.svg)
	58
	59	Note that the "drawMcd" method can take a second argument, which indicates the type of graph.
	60	* "bubble" draws the standard graph, as seen [here](https://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model#/media/File:ER_Diagram_MMORPG.png) for example
	61	* "compact" (default) use the same box for an entity and its attributes