README.md

   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