[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
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
d23e4446 BA	8	TODO list:
	9
	10	- functional integrity constraints (CIF),
	11	- inter-relations constraints (or, and, xor...),
	12	- inheritance with the right symbol (triangle).
48a55161	13
19addd10	14	Note: temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method.
525c4d2a BA	15
	16	-----
	17
	18	An entity is defined as follow
fe021b27	19
bf4fc3ed BA	20	[Entity]
	21	#attr1 (*)
	22	attr2 (*)
fe021b27	23
525c4d2a BA	24	with (\*) = optional SQL indications, and # denoting a (part of) a key.
	25
	26	A relationship is defined in this way
fe021b27	27
bf4fc3ed BA	28	{Relation}
	29	Entity C1
	30	Entity2 C2
	31	--
	32	attr1 (*)
	33	attr2 (*)
fe021b27	34
525c4d2a BA	35	where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2).
	36	Defining relationships with more than two attributes is easy: just add entities.
	37	Cardinality dictionary:
	38	* \* = 0..n
fe021b27	39	* \+ = 1..n
525c4d2a BA	40	* 1 = 1..1
	41	* ? = 0..1
	42
19addd10 BA	43	Special cardinalities are also available to indicate relative identification: `?R` and `1R`.
19addd10 BA	44
525c4d2a	45	To mark a weak entity, just surround its name by extra-brackets
fe021b27	46
525c4d2a	47	[[WeakEntity]]
fe021b27	48
525c4d2a	49	In the same way, a weak relation can be written
fe021b27	50
525c4d2a	51	{{WeakRelation}}
fe021b27	52
525c4d2a BA	53	The syntax for these two last is then the same as in the non-weak versions.
	54
	55	To indicate an inheritance relation, proceed as follow
fe021b27	56
bf4fc3ed BA	57	is_a
	58	Animal Cat Fish
	59	Planet Mars Venus
525c4d2a	60
3ca1e50c	61	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	62
	63	Note that the "drawMcd" method can take a second argument, which indicates the type of graph.
	64	* "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
	65	* "compact" (default) use the same box for an entity and its attributes