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 *Note:* at the moment only the conceptual graph is implemented, and no comments are allowed in textual descriptions.
   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.
  12
  13 -----
  14
  15 An entity is defined as follow
  16
  17     [Entity]
  18     #attr1 (*)
  19     attr2 (*)
  20
  21 with (\*) = optional SQL indications, and # denoting a (part of) a key.
  22
  23 A relationship is defined in this way
  24
  25     {Relation}
  26     Entity C1
  27     Entity2 C2
  28     --
  29     attr1 (*)
  30     attr2 (*)
  31
  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
  36  * \+ = 1..n
  37  * 1 = 1..1
  38  * ? = 0..1
  39
  40 To mark a weak entity, just surround its name by extra-brackets
  41
  42     [[WeakEntity]]
  43
  44 In the same way, a weak relation can be written
  45
  46     {{WeakRelation}}
  47
  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
  51
  52     is_a
  53     Animal Cat Fish
  54     Planet Mars Venus
  55
  56 Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example.svg)
  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