Add a new Makefile rule for instance emgraph that will generate an image representing the instance editorial model

Lodel/settings_format.py

@@ -12,4 +12,7 @@ MANDATORY = [
     'migration_options',
 ]
 
-ALLOWED = []
+ALLOWED = [
+    'em_graph_output',
+    'em_graph_format',
+]

install/utils.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 
 from loader import *
+import warnings
 
 def refreshdyn():
     import sys
@@ -24,4 +25,41 @@ def db_init():
     em = Model(EmBackendJson(Settings.em_file))
     em.migrate_handler(mh)
 
+def em_graph(output_file = None, image_format = None):
+    from EditorialModel.model import Model
+    from EditorialModel.backend.json_backend import EmBackendJson
+    from EditorialModel.backend.graphviz import EmBackendGraphviz
+    import subprocess
+    
+    if image_format is None:
+        if hasattr(Settings, 'em_graph_format'):
+            image_format = Settings.em_graph_format
+        else:
+            image_format = 'png'
+    if output_file is None:
+        if hasattr(Settings, 'em_graph_output'):
+            output_file = Settings.em_graph_output
+        else:
+            output_file = '/tmp/em_%s_graph.dot'
+    image_format = image_format.lower()
+    try:
+        output_file = output_file%Settings.sitename
+    except TypeError:
+        warnings.warn("Bad filename for em_graph output. The filename should be in the form '/foo/bar/file_%s_name.png")
+        pass
+
+    dot_file = output_file+".dot"
+    
+    graphviz_bckend = EmBackendGraphviz(dot_file)
+    edmod = Model(EmBackendJson(Settings.em_file))
+    graphviz_bckend.save(edmod)
+    dot_cmd = [
+        "dot",
+        "-T%s"%image_format,
+        dot_file
+    ]
+    with open(output_file, "w+") as outfp:
+        subprocess.check_call(dot_cmd, stdout=outfp)
+    os.unlink(dot_file)
+    print("Output image written in file : '%s'" % output_file)
 

settings.py

@@ -19,3 +19,6 @@ migration_options = {
     'foreign_keys': True,
     'drop_if_exists': False,
 }
+
+em_graph_format = 'png'
+em_graph_output = '/tmp/em_%s_graph.png'