[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.

*Note:* at the moment only the conceptual graph is implemented, and no comments are allowed in textual descriptions.
At least the former is planned, and also probably a way to indicate relative identifiers, and maybe links between relationships.

*Note bis:* 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

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
525c4d2a BA	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
ae81f305	8	Note: at the moment only the conceptual graph is implemented, and no comments are allowed in textual descriptions.
48a55161 BA	9	At least the former is planned, and also probably a way to indicate relative identifiers, and maybe links between relationships.
	10
	11	Note bis: temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method.
525c4d2a BA	12
	13	-----
	14
	15	An entity is defined as follow
fe021b27	16
bf4fc3ed BA	17	[Entity]
	18	#attr1 (*)
	19	attr2 (*)
fe021b27	20
525c4d2a BA	21	with (\*) = optional SQL indications, and # denoting a (part of) a key.
	22
	23	A relationship is defined in this way
fe021b27	24
bf4fc3ed BA	25	{Relation}
	26	Entity C1
	27	Entity2 C2
	28	--
	29	attr1 (*)
	30	attr2 (*)
fe021b27	31
525c4d2a BA	32	where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2).
	33	Defining relationships with more than two attributes is easy: just add entities.
	34	Cardinality dictionary:
	35	* \* = 0..n
fe021b27	36	* \+ = 1..n
525c4d2a BA	37	* 1 = 1..1
	38	* ? = 0..1
	39
	40	To mark a weak entity, just surround its name by extra-brackets
fe021b27	41
525c4d2a	42	[[WeakEntity]]
fe021b27	43
525c4d2a	44	In the same way, a weak relation can be written
fe021b27	45
525c4d2a	46	{{WeakRelation}}
fe021b27	47
525c4d2a BA	48	The syntax for these two last is then the same as in the non-weak versions.
	49
	50	To indicate an inheritance relation, proceed as follow
fe021b27	51
bf4fc3ed BA	52	is_a
	53	Animal Cat Fish
	54	Planet Mars Venus
525c4d2a	55
fe021b27	56	Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example.svg)
525c4d2a BA	57
	58	Note that the "drawMcd" method can take a second argument, which indicates the type of graph.
	59	* "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
	60	* "compact" (default) use the same box for an entity and its attributes