add docs and example

.gitignore

@@ -3,6 +3,7 @@ env
 test.json
 ERDotOutput.dot
 .pypirc
+imageFile.png
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

README.md

@@ -13,14 +13,134 @@
   </a>
 </p>
 
-> 
-
-## About
+> Creates Entity Relationship Diagrams from JSON code.
 
 ## Installation
+to install ERDot:
+
+```pip install ERDot```
+
+you may also need to [install graphvis](https://graphviz.org/download/) to be able to create images of the dot files generated.  
+
+## CLI Usage
+```
+Usage: erdot [OPTIONS]
+
+Options:
+  -i, --inputFile TEXT   The input ERDJSON file (.json)  [required]
+  -o, --outputFile TEXT  The graphvis dot file to write to (.dot)  (default: ERDotOutput.dot)
+  --help                 Show this message and exit.
+```
+
+Note that after generating the .dot file, you will still need to output it to your desired format using graphvis. An example of how to do this:
+
+```bash
+erdot -i inputFile.erd.json 
+
+dot ERDotOutput.dot -Tpng -o imageFile.png
+```
+
+## ERDJSON format:
+```json
+{
+    "tables":{
+        ...
+    },
+    "relations":[
+        ...
+    ],
+    "rankAdjustments":"...",
+    "label":"..."
+}   
+```
+
+Every single one of these sections are required, however, if you dont need that specific feature (for example label or rankAdjustments), just leave the value blank
+
+### table:
+Each table inside of the table section of the ERDJSON document is formated like this:
+
+```json
+"TableName": {
+      "*PrimaryKey": "Int(10)",
+      "+ForeignKey": "Int(10)",
+      "RandomData": "Char(70)"
+    }
+```
+
+the general idea is that the key is the column name, and the value is the type.
+
+you will also notice the `*` and `+` next to the column names, these indicate primary and foriegn keys respectively. You can combine two of these together into a primary foreign key, just by putting both a `*` and a `+` next to the name.
+
+### relations:
+each element in the relations array of the ERDJSON document is formatted like this:
+
+```json
+"TableOne:PrimaryKey 1--* TableTwo:ForeignKey"
+```
+
+There are three elements that make up the relation string, (1) the left hand side, (2) the cardinality indicator, and (3) the right hand side. 
+
+#### Left and Right hand side:
+The sides of the relation string consist of two elements, separated by a `:`. the text before the `:` indicates what table it is in, and the text after the `:` indicates what specific column it should use to link. (note how you dont include the `+` or `*` in the specific column text).
+
+#### Cardinality indicator:
+Each relationship must have two of these cardinalities in the indicator, separated by `--`:
+
+```
+Cardinality    Syntax
+0 or 1         ?
+exactly 1      1
+0 or more      *
+1 or more      +
+```
+
+So for example, the following defines a relationship between Person's PersonID primary key and BirthPlace's PersonID foreign key that reads "every person has exactly one birth place, linked together using PersonID":
+
+```python
+Person:PersonID *--1 BirthPlace:PersonID
+```
+
+### rankAdjustments
+applies graphvis' rank adjustments to adjust where the tables appear in the final image. (note that it is only one string)
+
+```js
+{ rank=min; TableOne Tabletwo }; // sets TableOne and TableTwo to be in the minimum rank (left)
+{ rank=same; TableThree TableFour }; // sets TableThree and TableFour to be in the same rank
+{ rank=max; TableFive }; // sets TableFive to be in the maximum rank (right)
+```
+
+### Label
+a string that sets what label will be drawn on top of the ERD, think of it like the title of the ERD.
+
+## Example ERDJSON:
+```json
+{
+    "tables":{
+        "Person":{
+            "*name":"char()",
+            "height":"int()",
+            "weight":"int()",
+            "birthDate":"date()",
+            "birthPlaceID":"int()"
+        },
+        "BirthPlace":{
+            "*id":"int()",
+            "birthCity":"char()",
+            "birthState":"char()",
+            "birthCountry":"char()"
+        }
+    },
+    "relations":[
+        "Person:birthPlaceID *--1 BirthPlace:id"
+    ],
+    "rankAdjustments":"",
+    "label":""
+}
+```
 
-## Usage
+which then creates this image:
 
+<img alt="logo" src="https://github.com/ehne/ERDot/raw/master/example/example.png" align="center"/>
 
 
 ## Author

example/example.dot

@@ -0,0 +1,54 @@
+
+digraph G {
+    graph [
+        nodesep=0.5;
+        rankdir="LR";
+        cencentrate=true;
+        splines="spline";
+        fontname="Helvetica";
+        pad="0.2,0.2",
+        label="",
+
+    ];
+
+    node [shape=plain, fontname="Helvetica"];
+    edge [
+        dir=both,
+        fontsize=12,
+        arrowsize=0.9,
+        penwidth=1.0,
+        labelangle=32,
+        labeldistance=1.8,
+        fontname="Helvetica"
+    ];
+
+    Person [ label=<
+        <table border="0" cellborder="1" cellspacing="0" >
+        <tr><td><i>Person</i></td></tr>
+        <tr><td port="name" align="left" cellpadding="5">PK name <font color="grey60">char()</font></td></tr>
+        <tr><td port="height" align="left" cellpadding="5">height <font color="grey60">int()</font></td></tr>
+        <tr><td port="weight" align="left" cellpadding="5">weight <font color="grey60">int()</font></td></tr>
+        <tr><td port="birthDate" align="left" cellpadding="5">birthDate <font color="grey60">date()</font></td></tr>
+        <tr><td port="birthPlaceID" align="left" cellpadding="5">birthPlaceID <font color="grey60">int()</font></td></tr>
+    </table>>];
+    BirthPlace [ label=<
+        <table border="0" cellborder="1" cellspacing="0" >
+        <tr><td><i>BirthPlace</i></td></tr>
+        <tr><td port="id" align="left" cellpadding="5">PK id <font color="grey60">int()</font></td></tr>
+        <tr><td port="birthCity" align="left" cellpadding="5">birthCity <font color="grey60">char()</font></td></tr>
+        <tr><td port="birthState" align="left" cellpadding="5">birthState <font color="grey60">char()</font></td></tr>
+        <tr><td port="birthCountry" align="left" cellpadding="5">birthCountry <font color="grey60">char()</font></td></tr>
+    </table>>];
+
+
+    Person:birthPlaceID->BirthPlace:id [
+        arrowhead=noneotee,
+
+        arrowtail=ocrow,
+    ];
+
+
+
+
+
+}

example/example.erd.json

@@ -0,0 +1,23 @@
+{
+    "tables":{
+        "Person":{
+            "*name":"char()",
+            "height":"int()",
+            "weight":"int()",
+            "birthDate":"date()",
+            "birthPlaceID":"int()"
+        },
+        "BirthPlace":{
+            "*id":"int()",
+            "birthCity":"char()",
+            "birthState":"char()",
+            "birthCountry":"char()"
+        }
+    },
+    "relations":[
+        "Person:birthPlaceID *--1 BirthPlace:id"
+    ],
+    "rankAdjustments":"",
+    "label":""
+}
+