projects / erdiag.git / blame
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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 | ||
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8 | ----- |
| 9 | ||
| 10 | An entity is defined as follow | |
| fe021b27 | 11 | |
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12 | [Entity] |
| 13 | #attr1 (*) | |
| 14 | attr2 (*) | |
| fe021b27 | 15 | |
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16 | with (\*) = optional SQL indications, and # denoting a (part of) a key. |
| 17 | ||
| 18 | A relationship is defined in this way | |
| fe021b27 | 19 | |
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20 | {Relation} |
| 21 | Entity C1 | |
| 22 | Entity2 C2 | |
| 23 | -- | |
| 24 | attr1 (*) | |
| 25 | attr2 (*) | |
| fe021b27 | 26 | |
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27 | where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2). |
| 28 | Defining relationships with more than two attributes is easy: just add entities. | |
| 29 | Cardinality dictionary: | |
| 30 | * \* = 0..n | |
| fe021b27 | 31 | * \+ = 1..n |
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32 | * 1 = 1..1 |
| 33 | * ? = 0..1 | |
| 34 | ||
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35 | Special cardinalities are also available to indicate relative identification: `?R` and `1R`. |
| 36 | ||
| 525c4d2a | 37 | To mark a weak entity, just surround its name by extra-brackets |
| fe021b27 | 38 | |
| 525c4d2a | 39 | [[WeakEntity]] |
| fe021b27 | 40 | |
| 525c4d2a | 41 | In the same way, a weak relation can be written |
| fe021b27 | 42 | |
| 525c4d2a | 43 | {{WeakRelation}} |
| fe021b27 | 44 | |
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45 | The syntax for these two last is then the same as in the non-weak versions. |
| 46 | ||
| 47 | To indicate an inheritance relation, proceed as follow | |
| fe021b27 | 48 | |
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49 | is_a |
| 50 | Animal Cat Fish | |
| 51 | Planet Mars Venus | |
| 525c4d2a | 52 | |
| b8af38fd | 53 | Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example\_\*.svg) |
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54 | |
| 55 | Note that the "drawMcd" method can take a second argument, which indicates the type of graph. | |
| 56 | * "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 | |
| 57 | * "compact" (default) use the same box for an entity and its attributes | |
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58 | |
| 59 | ----- | |
| 60 | ||
| 61 | **TODO** list: | |
| 62 | ||
| 63 | - functional integrity constraints (CIF) | |
| 64 | - inter-relations constraints (or, and, xor...) | |
| 65 | - inheritance with the right symbol (triangle) | |
| 66 | - put online somewhere (user enter graph description and get SVG + SQL) | |
| 67 | ||
| 68 | *Implementation note:* temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method. |