73 lines
2.5 KiB
Zig
73 lines
2.5 KiB
Zig
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const std = @import("std");
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const zollections = @import("zollections");
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const _repository = @import("repository.zig");
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const _relations = @import("relations.zig");
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/// Generic interface of a query result reader.
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pub fn QueryResultReader(comptime TableShape: type, comptime inlineRelations: ?[]const _relations.ModelRelation) type {
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_ = inlineRelations;
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return struct {
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const Self = @This();
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/// Generic interface of a query result reader instance.
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pub const Instance = struct {
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__interface: struct {
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instance: *anyopaque,
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next: *const fn (self: *anyopaque) anyerror!?TableShape, //TODO inline relations.
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},
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allocator: std.mem.Allocator,
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pub fn next(self: Instance) !?TableShape {
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return self.__interface.next(self.__interface.instance);
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}
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};
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_interface: struct {
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instance: *anyopaque,
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init: *const fn (self: *anyopaque, allocator: std.mem.Allocator) anyerror!Instance,
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},
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/// Initialize a reader instance.
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pub fn init(self: Self, allocator: std.mem.Allocator) !Instance {
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return self._interface.init(self._interface.instance, allocator);
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}
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};
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}
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/// Map query result to repository model structures, and load the given relations.
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pub fn ResultMapper(comptime Model: type, comptime TableShape: type, comptime repositoryConfig: _repository.RepositoryConfiguration(Model, TableShape), comptime inlineRelations: ?[]const _relations.ModelRelation, comptime relations: ?[]const _relations.ModelRelation) type {
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_ = relations;
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return struct {
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/// Map the query result to a repository result, with all the required relations.
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pub fn map(allocator: std.mem.Allocator, queryReader: QueryResultReader(TableShape, inlineRelations)) !_repository.RepositoryResult(Model) {
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// Create an arena for mapper data.
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var mapperArena = std.heap.ArenaAllocator.init(allocator);
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// Initialize query result reader.
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const reader = try queryReader.init(mapperArena.allocator());
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// Initialize models list.
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var models = std.ArrayList(*Model).init(allocator);
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defer models.deinit();
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// Get all raw models from the result reader.
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while (try reader.next()) |rawModel| {
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// Parse each raw model from the reader.
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const model = try allocator.create(Model);
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model.* = try repositoryConfig.fromSql(rawModel);
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//TODO inline relations.
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try models.append(model);
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}
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//TODO load relations?
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// Return a result with the models.
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return _repository.RepositoryResult(Model).init(allocator,
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zollections.Collection(Model).init(allocator, try models.toOwnedSlice()),
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mapperArena,
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);
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}
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};
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}
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