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.
  10
  11 -----
  12
  13 An entity is defined as follow
  14
  15     [Entity]
  16     #attr1 (*)
  17     attr2 (*)
  18
  19 with (\*) = optional SQL indications, and # denoting a (part of) a key.
  20
  21 A relationship is defined in this way
  22
  23     {Relation}
  24     Entity C1
  25     Entity2 C2
  26     --
  27     attr1 (*)
  28     attr2 (*)
  29
  30 where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2).
  31 Defining relationships with more than two attributes is easy: just add entities.
  32 Cardinality dictionary:
  33  * \* = 0..n
  34  * \+ = 1..n
  35  * 1 = 1..1
  36  * ? = 0..1
  37
  38 To mark a weak entity, just surround its name by extra-brackets
  39
  40     [[WeakEntity]]
  41
  42 In the same way, a weak relation can be written
  43
  44     {{WeakRelation}}
  45
  46 The syntax for these two last is then the same as in the non-weak versions.
  47
  48 To indicate an inheritance relation, proceed as follow
  49
  50     is_a
  51     Animal Cat Fish
  52     Planet Mars Venus
  53
  54 Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example.svg)
  55
  56 Note that the "drawMcd" method can take a second argument, which indicates the type of graph.
  57  * "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
  58  * "compact" (default) use the same box for an entity and its attributes