Simplify PRAGMA mapping and detection

No longer prefix PRAGMAS with `_`, so the mapping between the real
SQLite3 pragmas and the usage in the URI is more direct.

Use macros instead of case to detect pragmas from URI params and return
those as NamedTuple.

README.md

@@ -67,12 +67,12 @@ The following is the list of supported options:
 
 | Name                      | Connection key  |
 |---------------------------|-----------------|
-| [Busy Timeout][pragma-to] | `_busy_timeout` |
-| [Cache Size][pragma-cs] | `_cache_size` |
-| [Foreign Keys][pragma-fk] | `_foreign_keys` |
-| [Journal Mode][pragma-jm] | `_journal_mode` |
-| [Synchronous][pragma-sync] | `_synchronous` |
-| [WAL autocheckoint][pragma-walck] | `_wal_autocheckpoint` |
+| [Busy Timeout][pragma-to] | `busy_timeout` |
+| [Cache Size][pragma-cs] | `cache_size` |
+| [Foreign Keys][pragma-fk] | `foreign_keys` |
+| [Journal Mode][pragma-jm] | `journal_mode` |
+| [Synchronous][pragma-sync] | `synchronous` |
+| [WAL autocheckoint][pragma-walck] | `wal_autocheckpoint` |
 
 Please note there values passed using these connection keys are passed
 directly to SQLite3 without check or evaluation. Using incorrect values result

spec/connection_spec.cr

@@ -10,9 +10,9 @@ private def dump(source, target)
   end
 end
 
-private def it_sets_pragma_on_connection(pragma : String, option : String, value : String, expected, file = __FILE__, line = __LINE__)
-  it "sets pragma '#{pragma}' to #{expected} using '#{option}'", file, line do
-    with_db("#{DB_FILENAME}?#{option}=#{value}") do |db|
+private def it_sets_pragma_on_connection(pragma : String, value : String, expected, file = __FILE__, line = __LINE__)
+  it "sets pragma '#{pragma}' to #{expected}", file, line do
+    with_db("#{DB_FILENAME}?#{pragma}=#{value}") do |db|
       db.scalar("PRAGMA #{pragma}").should eq(expected)
     end
   end
@@ -78,32 +78,32 @@ describe Connection do
   end
 
   # adjust busy_timeout pragma (default is 0)
-  it_sets_pragma_on_connection "busy_timeout", "_busy_timeout", "1000", 1000
+  it_sets_pragma_on_connection "busy_timeout", "1000", 1000
 
   # adjust cache_size pragma (default is -2000, 2MB)
-  it_sets_pragma_on_connection "cache_size", "_cache_size", "-4000", -4000
+  it_sets_pragma_on_connection "cache_size", "-4000", -4000
 
   # enable foreign_keys, no need to test off (is the default)
-  it_sets_pragma_on_connection "foreign_keys", "_foreign_keys", "1", 1
-  it_sets_pragma_on_connection "foreign_keys", "_foreign_keys", "yes", 1
-  it_sets_pragma_on_connection "foreign_keys", "_foreign_keys", "true", 1
-  it_sets_pragma_on_connection "foreign_keys", "_foreign_keys", "on", 1
+  it_sets_pragma_on_connection "foreign_keys", "1", 1
+  it_sets_pragma_on_connection "foreign_keys", "yes", 1
+  it_sets_pragma_on_connection "foreign_keys", "true", 1
+  it_sets_pragma_on_connection "foreign_keys", "on", 1
 
   # change journal_mode (default is delete)
-  it_sets_pragma_on_connection "journal_mode", "_journal_mode", "delete", "delete"
-  it_sets_pragma_on_connection "journal_mode", "_journal_mode", "truncate", "truncate"
-  it_sets_pragma_on_connection "journal_mode", "_journal_mode", "persist", "persist"
+  it_sets_pragma_on_connection "journal_mode", "delete", "delete"
+  it_sets_pragma_on_connection "journal_mode", "truncate", "truncate"
+  it_sets_pragma_on_connection "journal_mode", "persist", "persist"
 
   # change synchronous mode (default is 2, FULL)
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "0", 0
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "off", 0
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "1", 1
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "normal", 1
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "2", 2
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "full", 2
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "3", 3
-  it_sets_pragma_on_connection "synchronous", "_synchronous", "extra", 3
+  it_sets_pragma_on_connection "synchronous", "0", 0
+  it_sets_pragma_on_connection "synchronous", "off", 0
+  it_sets_pragma_on_connection "synchronous", "1", 1
+  it_sets_pragma_on_connection "synchronous", "normal", 1
+  it_sets_pragma_on_connection "synchronous", "2", 2
+  it_sets_pragma_on_connection "synchronous", "full", 2
+  it_sets_pragma_on_connection "synchronous", "3", 3
+  it_sets_pragma_on_connection "synchronous", "extra", 3
 
   # change wal_autocheckpoint (default is 1000)
-  it_sets_pragma_on_connection "wal_autocheckpoint", "_wal_autocheckpoint", "0", 0
+  it_sets_pragma_on_connection "wal_autocheckpoint", "0", 0
 end

src/sqlite3/connection.cr

@@ -93,32 +93,40 @@ class SQLite3::Connection < DB::Connection
   private def process_query_params(uri : URI)
     return unless query = uri.query
 
-    pragmas = Hash(String, String).new
-
-    URI::Params.parse(query) do |key, value|
-      case key
-      when "_busy_timeout"
-        pragmas["busy_timeout"] = value
-      when "_cache_size"
-        pragmas["cache_size"] = value
-      when "_foreign_keys"
-        pragmas["foreign_keys"] = value
-      when "_journal_mode"
-        pragmas["journal_mode"] = value
-      when "_synchronous"
-        pragmas["synchronous"] = value
-      when "_wal_autocheckpoint"
-        pragmas["wal_autocheckpoint"] = value
-      end
-    end
+    detected_pragmas = extract_params(query,
+      busy_timeout: nil,
+      cache_size: nil,
+      foreign_keys: nil,
+      journal_mode: nil,
+      synchronous: nil,
+      wal_autocheckpoint: nil,
+    )
 
     # concatenate all into a single SQL string
     sql = String.build do |str|
-      pragmas.each do |key, value|
+      detected_pragmas.each do |key, value|
+        next unless value
         str << "PRAGMA #{key}=#{value};"
       end
     end
 
     check LibSQLite3.exec(@db, sql, nil, nil, nil)
   end
+
+  private def extract_params(query : String, **default : **T) forall T
+    res = default
+
+    URI::Params.parse(query) do |key, value|
+      {% begin %}
+        case key
+        {% for key in T %}
+        when {{ key.stringify }}
+          res = res.merge({{key.id}}: value)
+        {% end %}
+        end
+      {% end %}
+    end
+
+    res
+  end
 end