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:
   9
  10  - functional integrity constraints (CIF),
  11  - inter-relations constraints (or, and, xor...),
  12  - inheritance with the right symbol (triangle).
  13
  14 *Note:* temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method.
  15
  16 -----
  17
  18 An entity is defined as follow
  19
  20     [Entity]
  21     #attr1 (*)
  22     attr2 (*)
  23
  24 with (\*) = optional SQL indications, and # denoting a (part of) a key.
  25
  26 A relationship is defined in this way
  27
  28     {Relation}
  29     Entity C1
  30     Entity2 C2
  31     --
  32     attr1 (*)
  33     attr2 (*)
  34
  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
  39  * \+ = 1..n
  40  * 1 = 1..1
  41  * ? = 0..1
  42
  43 Special cardinalities are also available to indicate relative identification: `?R` and `1R`.
  44
  45 To mark a weak entity, just surround its name by extra-brackets
  46
  47     [[WeakEntity]]
  48
  49 In the same way, a weak relation can be written
  50
  51     {{WeakRelation}}
  52
  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
  56
  57     is_a
  58     Animal Cat Fish
  59     Planet Mars Venus
  60
  61 Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example\_\*.svg)
  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