Add follow table

src/api/services/follows.zig

@@ -0,0 +1,142 @@
+const std = @import("std");
+const util = @import("util");
+const sql = @import("sql");
+
+const common = @import("./common.zig");
+
+const Uuid = util.Uuid;
+const DateTime = util.DateTime;
+
+pub const Follow = struct {
+    id: Uuid,
+
+    follower_id: Uuid,
+    following_id: Uuid,
+
+    created_at: DateTime,
+};
+
+pub fn create(db: anytype, follower_id: Uuid, following_id: Uuid, alloc: std.mem.Allocator) !void {
+    if (Uuid.eql(follower_id, following_id)) return error.SelfFollow;
+    const now = DateTime.now();
+    const id = Uuid.randv4(util.getThreadPrng());
+
+    db.insert("follow", .{
+        .id = id,
+        .follower_id = follower_id,
+        .following_id = following_id,
+        .created_at = now,
+    }, alloc) catch |err| return switch (err) {
+        error.ForeignKeyViolation => error.NotFound,
+        error.UniqueViolation => error.NotUnique,
+        else => error.DatabaseFailure,
+    };
+}
+
+const max_max_items = 100;
+
+pub const QueryArgs = struct {
+    pub const Direction = common.Direction;
+    pub const PageDirection = common.PageDirection;
+    pub const Prev = std.meta.Child(std.meta.fieldInfo(@This(), .prev).field_type);
+
+    pub const OrderBy = enum {
+        created_at,
+    };
+
+    max_items: usize = 20,
+
+    follower_id: ?Uuid = null,
+    following_id: ?Uuid = null,
+
+    order_by: OrderBy = .created_at,
+
+    direction: Direction = .descending,
+
+    prev: ?struct {
+        id: Uuid,
+        order_val: union(OrderBy) {
+            created_at: DateTime,
+        },
+    } = null,
+
+    page_direction: PageDirection = null,
+};
+
+pub const QueryResult = struct {
+    items: []Follow,
+
+    prev_page: QueryArgs,
+    next_page: QueryArgs,
+};
+
+pub fn query(db: anytype, args: QueryArgs, alloc: std.mem.Allocator) !QueryResult {
+    var builder = sql.QueryBuilder.init(alloc);
+    defer builder.deinit();
+
+    try builder.appendSlice(
+        \\SELECT follow.follower_id, follow.followee_id, follow.created_at
+        \\FROM follow
+        \\
+    );
+
+    if (args.follower_id != null) try builder.andWhere("follow.follower_id = $1");
+    if (args.following_id != null) try builder.andWhere("follow.following_id = $2");
+
+    if (args.prev != null) {
+        try builder.andWhere("(follow.id, follow.created_at)");
+        switch (args.page_direction) {
+            .forward => try builder.appendSlice(" < "),
+            .backward => try builder.appendSlice(" > "),
+        }
+        try builder.appendSlice("($3, $4)");
+    }
+
+    try builder.appendSlice(
+        \\
+        \\ORDER BY follow.created_at DESC
+        \\LIMIT $6
+        \\
+    );
+
+    const max_items = if (args.max_items > max_max_items) max_max_items else args.max_items;
+    const query_args = .{
+        args.follower_id,
+        args.following_id,
+        if (args.prev) |p| p.id else null,
+        if (args.prev) |p| p.created_at else null,
+        max_items,
+    };
+
+    const results = try db.QueryRowsWithOptions(
+        Follow,
+        try builder.terminate(),
+        query_args,
+        max_items,
+        .{ .allocator = alloc, .ignore_unused_arguments = true },
+    );
+    errdefer util.deepFree(alloc, results);
+
+    var next_page = args;
+    var prev_page = args;
+    prev_page.page_direction = .backward;
+    next_page.page_direction = .forward;
+    if (results.len != 0) {
+        prev_page.prev = .{
+            .id = results[0].id,
+            .created_at = results[0].created_at,
+        };
+
+        next_page.prev = .{
+            .id = results[results.len - 1].id,
+            .created_at = results[results.len - 1].created_at,
+        };
+    }
+    // TODO: this will give incorrect links on an empty page
+
+    return QueryResult{
+        .items = results,
+        .next_page = next_page,
+        .prev_page = prev_page,
+    };
+}

src/api/services/notes.zig

@@ -138,7 +138,7 @@ pub fn query(db: anytype, args: QueryArgs, alloc: std.mem.Allocator) !QueryResul
         max_items,
         .{ .allocator = alloc, .ignore_unused_arguments = true },
     );
-    errdefer util.deepFree(results);
+    errdefer util.deepFree(alloc, results);
 
     var next_page = args;
     var prev_page = args;

src/main/migrations.zig

@@ -189,4 +189,20 @@ const migrations: []const Migration = &.{
         \\DROP TABLE community;
         ,
     },
+    .{
+        .name = "follows",
+        .up = 
+        \\CREATE TABLE follow(
+        \\  id UUID NOT NULL PRIMARY KEY,
+        \\
+        \\  follower_id UUID NOT NULL,
+        \\  following_id UUID NOT NULL,
+        \\
+        \\  created_at TIMESTAMPTZ NOT NULL,
+        \\
+        \\  UNIQUE(follower_id, following_id)
+        \\);
+        ,
+        .down = "DROP TABLE follow",
+    },
 };