URL hashing is now off by default - closes #418

Prior to this commit Datasette would calculate the content hash of every
database and redirect to a URL containing that hash, like so:

    https://v0-27.datasette.io/fixtures => https://v0-27.datasette.io/fixtures-dd88475

This assumed that all databases were opened in immutable mode and were not
expected to change.

This will be changing as a result of #419 - so this commit takes the first step
in implementing that change by changing this default behaviour. Datasette will
now only redirect hash-free URLs under two circumstances:

* The new `hash_urls` config option is set to true (it defaults to false).
* The user passes `?_hash=1` in the URL

datasette/templates/database.html

@@ -12,12 +12,12 @@
 {% block content %}
 <div class="hd"><a href="/">home</a></div>
 
-<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_hash[:6] }}">{{ metadata.title or database }}</h1>
+<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_color(database) }}">{{ metadata.title or database }}</h1>
 
 {% block description_source_license %}{% include "_description_source_license.html" %}{% endblock %}
 
 {% if config.allow_sql %}
-    <form class="sql" action="/{{ database }}-{{ database_hash }}" method="get">
+    <form class="sql" action="{{ database_url(database) }}" method="get">
         <h3>Custom SQL query</h3>
         <p><textarea name="sql">{% if tables %}select * from {{ tables[0].name|escape_sqlite }}{% else %}select sqlite_version(){% endif %}</textarea></p>
         <p><input type="submit" value="Run SQL"></p>
@@ -27,7 +27,7 @@
 {% for table in tables %}
 {% if show_hidden or not table.hidden %}
 <div class="db-table">
-    <h2><a href="/{{ database }}-{{ database_hash }}/{{ table.name|quote_plus }}">{{ table.name }}</a>{% if table.hidden %}<em> (hidden)</em>{% endif %}</h2>
+    <h2><a href="{{ database_url(database) }}/{{ table.name|quote_plus }}">{{ table.name }}</a>{% if table.hidden %}<em> (hidden)</em>{% endif %}</h2>
     <p><em>{% for column in table.columns[:9] %}{{ column }}{% if not loop.last %}, {% endif %}{% endfor %}{% if table.columns|length > 9 %}...{% endif %}</em></p>
     <p>{{ "{:,}".format(table.count) }} row{% if table.count == 1 %}{% else %}s{% endif %}</p>
 </div>
@@ -35,14 +35,14 @@
 {% endfor %}
 
 {% if hidden_count and not show_hidden %}
-    <p>... and <a href="/{{ database }}-{{ database_hash }}?_show_hidden=1">{{ "{:,}".format(hidden_count) }} hidden table{% if hidden_count == 1 %}{% else %}s{% endif %}</a></p>
+    <p>... and <a href="{{ database_url(database) }}?_show_hidden=1">{{ "{:,}".format(hidden_count) }} hidden table{% if hidden_count == 1 %}{% else %}s{% endif %}</a></p>
 {% endif %}
 
 {% if views %}
     <h2>Views</h2>
     <ul>
         {% for view in views %}
-            <li><a href="/{{ database }}-{{ database_hash }}/{{ view|urlencode }}">{{ view }}</a></li>
+            <li><a href="{{ database_url(database) }}/{{ view|urlencode }}">{{ view }}</a></li>
         {% endfor %}
     </ul>
 {% endif %}
@@ -51,13 +51,13 @@
     <h2>Queries</h2>
     <ul>
         {% for query in queries %}
-            <li><a href="/{{ database }}-{{ database_hash }}/{{ query.name|urlencode }}" title="{{ query.description or query.sql }}">{{ query.title or query.name }}</a></li>
+            <li><a href="{{ database_url(database) }}/{{ query.name|urlencode }}" title="{{ query.description or query.sql }}">{{ query.title or query.name }}</a></li>
         {% endfor %}
     </ul>
 {% endif %}
 
 {% if config.allow_download and database != ":memory:" %}
-    <p class="download-sqlite">Download SQLite DB: <a href="/{{ database }}-{{ database_hash }}.db">{{ database }}.db</a> <em>{{ format_bytes(size) }}</em></p>
+    <p class="download-sqlite">Download SQLite DB: <a href="{{ database_url(database) }}.db">{{ database }}.db</a> <em>{{ format_bytes(size) }}</em></p>
 {% endif %}
 
 {% include "_codemirror_foot.html" %}

datasette/templates/query.html

@@ -19,13 +19,13 @@
 {% block body_class %}query db-{{ database|to_css_class }}{% endblock %}
 
 {% block content %}
-<div class="hd"><a href="/">home</a> / <a href="/{{ database }}-{{ database_hash }}">{{ database }}</a></div>
+<div class="hd"><a href="/">home</a> / <a href="{{ database_url(database) }}">{{ database }}</a></div>
 
-<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_hash[:6] }}">{{ metadata.title or database }}</h1>
+<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_color(database) }}">{{ metadata.title or database }}</h1>
 
 {% block description_source_license %}{% include "_description_source_license.html" %}{% endblock %}
 
-<form class="sql" action="/{{ database }}-{{ database_hash }}{% if canned_query %}/{{ canned_query }}{% endif %}" method="get">
+<form class="sql" action="{{ database_url(database) }}{% if canned_query %}/{{ canned_query }}{% endif %}" method="get">
     <h3>Custom SQL query{% if display_rows %} returning {% if truncated %}more than {% endif %}{{ "{:,}".format(display_rows|length) }} row{% if display_rows|length == 1 %}{% else %}s{% endif %}{% endif %} <span class="show-hide-sql">{% if hide_sql %}(<a href="{{ path_with_removed_args(request, {'_hide_sql': '1'}) }}">show</a>){% else %}(<a href="{{ path_with_added_args(request, {'_hide_sql': '1'}) }}">hide</a>){% endif %}</span></h3>
     {% if not hide_sql %}
         {% if editable and config.allow_sql %}

datasette/templates/row.html

@@ -16,9 +16,9 @@
 {% block body_class %}row db-{{ database|to_css_class }} table-{{ table|to_css_class }}{% endblock %}
 
 {% block content %}
-<div class="hd"><a href="/">home</a> / <a href="/{{ database }}-{{ database_hash }}">{{ database }}</a> / <a href="/{{ database }}-{{ database_hash }}/{{ table|quote_plus }}">{{ table }}</a></div>
+<div class="hd"><a href="/">home</a> / <a href="{{ database_url(database) }}">{{ database }}</a> / <a href="{{ database_url(database) }}/{{ table|quote_plus }}">{{ table }}</a></div>
 
-<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_hash[:6] }}">{{ table }}: {{ ', '.join(primary_key_values) }}</a></h1>
+<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_color(database) }}">{{ table }}: {{ ', '.join(primary_key_values) }}</a></h1>
 
 {% block description_source_license %}{% include "_description_source_license.html" %}{% endblock %}
 
@@ -31,7 +31,7 @@
     <ul>
         {% for other in foreign_key_tables %}
             <li>
-                <a href="/{{ database }}-{{ database_hash }}/{{ other.other_table|quote_plus }}?{{ other.other_column }}={{ ', '.join(primary_key_values) }}">
+                <a href="{{ database_url(database) }}/{{ other.other_table|quote_plus }}?{{ other.other_column }}={{ ', '.join(primary_key_values) }}">
                     {{ "{:,}".format(other.count) }} row{% if other.count == 1 %}{% else %}s{% endif %}</a>
                 from {{ other.other_column }} in {{ other.other_table }}
             </li>

datasette/templates/table.html

@@ -17,9 +17,9 @@
 {% block body_class %}table db-{{ database|to_css_class }} table-{{ table|to_css_class }}{% endblock %}
 
 {% block content %}
-<div class="hd"><a href="/">home</a> / <a href="/{{ database }}-{{ database_hash }}">{{ database }}</a></div>
+<div class="hd"><a href="/">home</a> / <a href="{{ database_url(database) }}">{{ database }}</a></div>
 
-<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_hash[:6] }}">{{ metadata.title or table }}{% if is_view %} (view){% endif %}</h1>
+<h1 style="padding-left: 10px; border-left: 10px solid #{{ database_color(database) }}">{{ metadata.title or table }}{% if is_view %} (view){% endif %}</h1>
 
 {% block description_source_license %}{% include "_description_source_license.html" %}{% endblock %}
 
@@ -29,7 +29,7 @@
     </h3>
 {% endif %}
 
-<form class="filters" action="/{{ database }}-{{ database_hash }}/{{ table|quote_plus }}" method="get">
+<form class="filters" action="{{ database_url(database) }}/{{ table|quote_plus }}" method="get">
     {% if supports_search %}
         <div class="search-row"><label for="_search">Search:</label><input id="_search" type="search" name="_search" value="{{ search }}"></div>
     {% endif %}
@@ -89,7 +89,7 @@
 </form>
 
 {% if query.sql and config.allow_sql %}
-    <p><a class="not-underlined" title="{{ query.sql }}" href="/{{ database }}-{{ database_hash }}?{{ {'sql': query.sql}|urlencode|safe }}{% if query.params %}&amp;{{ query.params|urlencode|safe }}{% endif %}">&#x270e; <span class="underlined">View and edit SQL</span></a></p>
+    <p><a class="not-underlined" title="{{ query.sql }}" href="{{ database_url(database) }}?{{ {'sql': query.sql}|urlencode|safe }}{% if query.params %}&amp;{{ query.params|urlencode|safe }}{% endif %}">&#x270e; <span class="underlined">View and edit SQL</span></a></p>
 {% endif %}
 
 <p class="export-links">This data as <a href="{{ url_json }}">JSON</a>{% if display_rows %}, <a href="{{ url_csv }}">CSV</a> (<a href="#export">advanced</a>){% endif %}</p>