Move schema parsing to its own package

pkg/schema/parse.go

@@ -0,0 +1,64 @@
+package schema
+
+import (
+	"gas_stack/pkg/textutils"
+	"strings"
+
+	"github.com/jinzhu/inflection"
+	"github.com/jmoiron/sqlx"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// InitDB creates an in-memory DB from a given schema string.
+func InitDB(sql_schema string) *sqlx.DB {
+	db := sqlx.MustOpen("sqlite3", ":memory:")
+	db.MustExec(sql_schema)
+	db.MustExec(`
+		create temporary view tables as
+		    select l.schema, l.name, l.type, l.ncol, l.wr, l.strict
+		      from sqlite_schema s
+		 left join pragma_table_list l on s.name = l.name
+		     where s.type = 'table';
+
+		create temporary view columns as
+		    select tables.name as table_name,
+		           table_info.name as column_name,
+		           lower(table_info.type) as column_type,
+		           "notnull",
+	               dflt_value is not null as has_default_value,
+		           ifnull(dflt_value, 0) dflt_value,
+		           pk as is_primary_key,
+       	           fk."table" is not null as is_foreign_key,
+		           ifnull(fk."table", '') as fk_target_table,
+		           ifnull(fk."to", '') as fk_target_column
+		      from tables
+		      join pragma_table_info(tables.name) as table_info
+		 left join pragma_foreign_key_list(tables.name) as fk on fk."from" = column_name;
+	`)
+	return db
+}
+
+// SchemaFromDB takes a DB connection, checks its schema metadata tables, and returns a Schema.
+func SchemaFromDB(db *sqlx.DB) Schema {
+	ret := Schema{}
+
+	var tables []Table
+	err := db.Select(&tables, `select name, strict from tables`)
+	if err != nil {
+		panic(err)
+	}
+
+	for _, tbl := range tables {
+		tbl.TypeName = textutils.SnakeToCamel(inflection.Singular(tbl.TableName))
+		tbl.TypeIDName = tbl.TypeName + "ID"
+		tbl.VarName = strings.ToLower(string(tbl.TableName[0]))
+
+		err := db.Select(&tbl.Columns, `select * from columns where table_name = ?`, tbl.TableName)
+		if err != nil {
+			panic(err)
+		}
+		ret[tbl.TableName] = tbl
+	}
+	return ret
+}