add sqlite query generator to the core API

silkmvc/core/sqlite.lua

@@ -17,9 +17,241 @@ sqlite.getdb = function(name)
     end
 end
 
--- create class
+--- SQL generator
+SQLQueryGenerator = Object:extends{}
+
+function SQLQueryGenerator:initialize()
+end
+
+function SQLQueryGenerator:parse()
+    local j, w, o, f
+    j = self:sql_joins()
+    if self.where then
+        w = self:sql_where("$and", self.where)
+    end
+    f = self:sql_fields()
+    o = self:sql_order()
+    return f, w, j, o
+end
+
+function SQLQueryGenerator:sql_select()
+    local v, f, w, j, o = pcall(SQLQueryGenerator.parse, self)
+    if not v then
+        return v, f
+    end
+    local segments = {"SELECT"}
+    if f then
+        table.insert(segments, f)
+    else
+        table.insert(segments, "*")
+    end
+    table.insert(segments, "FROM")
+    table.insert(segments, self.table_name)
+    if j then
+        table.insert(segments, j)
+    end
+    if w then
+        table.insert(segments, "WHERE")
+        table.insert(segments, w)
+    end
+
+    if o then
+        table.insert(segments, "ORDER BY")
+        table.insert(segments, o)
+    end
+
+    return true, table.concat(segments, " ")
+end
+
+function SQLQueryGenerator:sql_delete()
+    local v, f, w, j, o = pcall(SQLQueryGenerator.parse, self)
+    if not v then
+        return v, f
+    end
+    local segments = {"DELETE"}
+    table.insert(segments, "FROM")
+    table.insert(segments, self.table_name)
+    if j then
+        table.insert(segments, j)
+    end
+    if w then
+        table.insert(segments, "WHERE")
+        table.insert(segments, w)
+    end
+    return true, table.concat(segments, " ")
+end
+
+function SQLQueryGenerator:error(msg, ...)
+    local emsg = string.format(msg or "ERROR", ...)
+    LOG_ERROR(msg, ...)
+    error(emsg)
+end
+
+function SQLQueryGenerator:infer_field(k)
+    if not self.table_name then
+        self:error("Unknown input table (specified by `table_name` field)")
+    end
+    if not self.joins then
+        return k
+    end
+    if k:match("%.") then
+        return k
+    end
+    return string.format("%s.%s", self.table_name, k)
+end
+
+function SQLQueryGenerator:sql_joins()
+    if not self.joins then
+        return nil
+    end
+    local joins = {}
+    for k, v in pairs(self.joins) do
+        local arr = explode(v, ".")
+        if not arr[2] then
+            self:error("SQL JOIN: Other table name parsing error: " .. v)
+        end
+        table.insert(joins, string.format("INNER JOIN %s ON %s = %s", arr[1], self:infer_field(k), v))
+    end
+    return table.concat(joins, " ")
+end
+
+function SQLQueryGenerator:sql_fields()
+    if not self.fields then
+        return nil
+    end
+    local arr = {}
+    for k, v in ipairs(self.fields) do
+        arr[k] = self:infer_field(v)
+    end
+    return string.format("(%s)", table.concat(arr, ","))
+end
+
+function SQLQueryGenerator:sql_order()
+    local tb = {}
+    for k, v in ipairs(self.order) do
+        local arr = explode(v, "$")
+        if #arr ~= 2 then
+            self:error("Invalid field order format %s", v)
+        end
+        if arr[2] == "asc" then
+            table.insert(tb, self:infer_field(arr[1]) .. " ASC")
+        elseif arr[2] == "desc" then
+            table.insert(tb, self:infer_field(arr[1]) .. " DESC")
+        else
+            self:error("Unknown order %s", arr[2])
+        end
+    end
+    return table.concat(tb, ",")
+end
+
+function SQLQueryGenerator:sql_where(cond, obj)
+    if not obj then
+        self:error("%s condition is nil", cond)
+    end
+    local conds = {}
+    local op = " AND "
+    if cond == "$or" then
+        op = " OR "
+    end
+    if type(obj) ~= 'table' then
+        self:error("Invalid input data for operator " .. cond)
+    end
+    for k, v in pairs(obj) do
+        if k == "$and" or k == "$or" then
+            table.insert(conds, self:sql_where(k, v))
+        else
+            table.insert(conds, self:binary(k, v))
+        end
+    end
+
+    return string.format("(%s)", table.concat(conds, op))
+end
+
+function SQLQueryGenerator:parse_value(v, types)
+    if not types[type(v)] then
+        self:error("Type error: unexpected type %d", type(v))
+    end
+    if type(v) == "number" then
+        return tostring(v)
+    end
+    if type(v) == "string" then
+        return string.format("'%s'", v:gsub("'", "''"))
+    end
+end
+function SQLQueryGenerator:binary(k, v)
+    local arr = explode(k, "$");
+    if #arr > 2 then
+        self:error("Invalid left hand side format: %s", k)
+    end
+    if #arr == 2 then
+        if arr[2] == "gt" then
+            return string.format("(%s > %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['number'] = true
+            }))
+        elseif arr[2] == "gte" then
+            return string.format("(%s >= %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['number'] = true
+            }))
+        elseif arr[2] == "lt" then
+            return string.format("(%s < %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['number'] = true
+            }))
+        elseif arr[2] == "lte" then
+            return string.format("(%s <= %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['number'] = true
+            }))
+        elseif arr[2] == "ne" then
+            return string.format("(%s != %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['number'] = true,
+                ['string'] = true
+            }))
+        elseif arr[2] == "between" then
+            return string.format("(%s BETWEEN %s AND %s)", self:infer_field(arr[1]), self:parse_value(v[1], {
+                ['number'] = true
+            }), self:parse_value(v[2], {
+                ['number'] = true
+            }))
+        elseif arr[2] == "not_between" then
+            return string.format("(%s NOT BETWEEN %s AND %s)", self:infer_field(arr[1]), self:parse_value(v[1], {
+                ['number'] = true
+            }), self:parse_value(v[2], {
+                ['number'] = true
+            }))
+        elseif arr[2] == "in" then
+            return string.format("(%s IN [%s,%s])", self:infer_field(arr[1]), self:parse_value(v[1], {
+                ['number'] = true
+            }), self:parse_value(v[2], {
+                ['number'] = true
+            }))
+        elseif arr[2] == "not_in" then
+            return string.format("(%s NOT IN [%s,%s])", self:infer_field(arr[1]), self:parse_value(v[1], {
+                ['number'] = true
+            }), self:parse_value(v[2], {
+                ['number'] = true
+            }))
+        elseif arr[2] == "like" then
+            return string.format("(%s LIKE %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['string'] = true
+            }))
+        elseif arr[2] == "not_like" then
+            return string.format("(%s NOT LIKE %s)", self:infer_field(arr[1]), self:parse_value(v, {
+                ['string'] = true
+            }))
+        else
+            self:error("Unsupported operator `%s`", arr[2])
+        end
+    else
+        return string.format("(%s=%s)", self:infer_field(arr[1]), self:parse_value(v, {
+            ['number'] = true,
+            ['string'] = true
+        }))
+    end
+end
+
+--- create class DBModel
+--- TODO: This class shall use the SQLQueryGenerator to create the query
 DBModel = Object:inherit{
-    db = nil,
+    db = nil
 }
 
 function DBModel:createTable(name, m)
@@ -58,7 +290,7 @@ function DBModel:insert(name, m)
 end
 
 function DBModel:get(name, id)
-    local records = self:query( string.format("SELECT * FROM %s WHERE id=%d", name, id))
+    local records = self:query(string.format("SELECT * FROM %s WHERE id=%d", name, id))
     if records and #records == 1 then
         return records[1]
     end
@@ -66,7 +298,7 @@ function DBModel:get(name, id)
 end
 
 function DBModel:getAll(name)
-    local data = self:query( "SELECT * FROM " .. name)
+    local data = self:query("SELECT * FROM " .. name)
     if not data then
         return nil
     end
@@ -102,7 +334,7 @@ function DBModel:find(name, cond)
         -- print(sel)
     end
     -- print(cnd)
-    local data = self:query( string.format("SELECT %s FROM %s WHERE %s", sel, name, cnd))
+    local data = self:query(string.format("SELECT %s FROM %s WHERE %s", sel, name, cnd))
     if data == nil then
         return nil
     end
@@ -116,7 +348,7 @@ end
 
 function DBModel:query(sql)
     local data, error = sqlite.query(self.db, sql)
-    --LOG_DEBUG(sql)
+    -- LOG_DEBUG(sql)
     if not data then
         LOG_ERROR("Error querying recorda SQL[%s]: %s", sql, error or "")
         return nil
@@ -125,7 +357,7 @@ function DBModel:query(sql)
 end
 
 function DBModel:exec(sql)
-    --LOG_DEBUG(sql)
+    -- LOG_DEBUG(sql)
     local ret, err = sqlite.exec(self.db, sql)
     if not ret then
         LOG_ERROR("Error execute [%s]: %s", sql, err or "")