diff --git a/build.zig.zon b/build.zig.zon
index cd300e7..c3617ae 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -7,8 +7,8 @@
             .hash = "1220d0e8734628fd910a73146e804d10a3269e3e7d065de6bb0e3e88d5ba234eb163",
         },
         .zmpl = .{
-            .url = "https://github.com/jetzig-framework/zmpl/archive/7f2817df78404b8a46c637c212ec1a27a66306fa.tar.gz",
-            .hash = "12203a2ef05a4c3a76c1436e96c0a0aa5fc8e8406d56e50b1e9c94c394225c113b0e",
+            .url = "https://github.com/jetzig-framework/zmpl/archive/7b7452bc7fdb0bd2f8a6a9c4e9312900b486aeba.tar.gz",
+            .hash = "1220ed127f38fa51df53a85b3cc2030a7555e34058db7fd374ebaef817abb43d35f7",
         },
         .jetkv = .{
             .url = "https://github.com/jetzig-framework/jetkv/archive/2b1130a48979ea2871c8cf6ca89c38b1e7062839.tar.gz",
diff --git a/cli/commands/generate/view.zig b/cli/commands/generate/view.zig
index 9d1b483..edcbc97 100644
--- a/cli/commands/generate/view.zig
+++ b/cli/commands/generate/view.zig
@@ -116,8 +116,7 @@ fn parseAction(arg: []const u8) ?Action {
 fn writeAction(allocator: std.mem.Allocator, writer: anytype, action: Action) !void {
     const function = try std.fmt.allocPrint(
         allocator,
-        \\pub fn {s}({s}request: *jetzig.{s}, data: *jetzig.Data) !jetzig.View {{
-        \\    _ = data;{s}
+        \\pub fn {s}({s}request: *jetzig.{s}) !jetzig.View {{
         \\    return request.render({s});
         \\}}
         \\
diff --git a/demo/src/app/views/params.zig b/demo/src/app/views/params.zig
index 16a47b0..1eff17b 100644
--- a/demo/src/app/views/params.zig
+++ b/demo/src/app/views/params.zig
@@ -2,13 +2,79 @@ const std = @import("std");
 const jetzig = @import("jetzig");
 
 pub fn post(request: *jetzig.Request) !jetzig.View {
+    const Params = struct {
+        // Required param - `expectParams` returns `null` if not present:
+        name: []const u8,
+        // Enum params are converted from string, `expectParams` returns `null` if no match:
+        favorite_animal: enum { cat, dog, raccoon },
+        // Optional params are not required. Numbers are coerced from strings. `expectParams`
+        // returns `null` if a type coercion fails.
+        age: ?u8 = 100,
+    };
+    const params = try request.expectParams(Params) orelse {
+        // Inspect information about the failed params with `request.paramsInfo()`:
+        // std.debug.print("{?}\n", .{try request.paramsInfo()});
+        return request.fail(.unprocessable_entity);
+    };
+
+    var root = try request.data(.object);
+    try root.put("info", params);
+
     return request.render(.created);
 }
 
-test "post" {
+test "post query params" {
     var app = try jetzig.testing.app(std.testing.allocator, @import("routes"));
     defer app.deinit();
 
-    const response = try app.request(.POST, "/params", .{});
-    try response.expectStatus(.created);
+    const response1 = try app.request(.POST, "/params", .{
+        .params = .{
+            .name = "Bob",
+            .favorite_animal = "raccoon",
+        },
+    });
+    try response1.expectStatus(.created);
+
+    const response2 = try app.request(.POST, "/params", .{
+        .params = .{
+            .name = "Bob",
+            .favorite_animal = "platypus",
+        },
+    });
+    try response2.expectStatus(.unprocessable_entity);
+}
+
+test "post json" {
+    var app = try jetzig.testing.app(std.testing.allocator, @import("routes"));
+    defer app.deinit();
+
+    const response1 = try app.request(.POST, "/params", .{
+        .json = .{
+            .name = "Bob",
+            .favorite_animal = "raccoon",
+        },
+    });
+    try response1.expectJson("$.info.name", "Bob");
+    try response1.expectJson("$.info.favorite_animal", "raccoon");
+    try response1.expectJson("$.info.age", 100);
+
+    const response2 = try app.request(.POST, "/params", .{
+        .json = .{
+            .name = "Hercules",
+            .favorite_animal = "cat",
+            .age = 11,
+        },
+    });
+    try response2.expectJson("$.info.name", "Hercules");
+    try response2.expectJson("$.info.favorite_animal", "cat");
+    try response2.expectJson("$.info.age", 11);
+
+    const response3 = try app.request(.POST, "/params", .{
+        .json = .{
+            .name = "Hercules",
+            .favorite_animal = "platypus",
+            .age = 11,
+        },
+    });
+    try response3.expectStatus(.unprocessable_entity);
 }
diff --git a/src/jetzig/colors.zig b/src/jetzig/colors.zig
index cc776d3..d62379e 100644
--- a/src/jetzig/colors.zig
+++ b/src/jetzig/colors.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const builtin = @import("builtin");
 
 const types = @import("types.zig");
+const jetzig = @import("../jetzig.zig");
 
 // Must be consistent with `std.io.tty.Color` for Windows compatibility.
 pub const codes = .{
@@ -108,6 +109,8 @@ pub fn colorize(color: std.io.tty.Color, buf: []u8, input: []const u8, is_colori
 }
 
 fn wrap(comptime attribute: []const u8, comptime message: []const u8) []const u8 {
+    if (comptime jetzig.environment == .production) return message;
+
     return codes.escape ++ attribute ++ message ++ codes.escape ++ codes.reset;
 }
 
diff --git a/src/jetzig/http.zig b/src/jetzig/http.zig
index 03c21e2..3426606 100644
--- a/src/jetzig/http.zig
+++ b/src/jetzig/http.zig
@@ -16,6 +16,7 @@ pub const status_codes = @import("http/status_codes.zig");
 pub const StatusCode = status_codes.StatusCode;
 pub const middleware = @import("http/middleware.zig");
 pub const mime = @import("http/mime.zig");
+pub const params = @import("http/params.zig");
 
 pub const SimplifiedRequest = struct {
     location: ?[]const u8,
diff --git a/src/jetzig/http/Request.zig b/src/jetzig/http/Request.zig
index a7fe119..6fb97d3 100644
--- a/src/jetzig/http/Request.zig
+++ b/src/jetzig/http/Request.zig
@@ -23,6 +23,7 @@ status_code: jetzig.http.status_codes.StatusCode = .not_found,
 response_data: *jetzig.data.Data,
 query_params: ?*jetzig.http.Query = null,
 query_body: ?*jetzig.http.Query = null,
+_params_info: ?jetzig.http.params.ParamsInfo = null,
 multipart: ?jetzig.http.MultipartQuery = null,
 parsed_multipart: ?*jetzig.data.Data = null,
 _cookies: ?*jetzig.http.Cookies = null,
@@ -172,6 +173,15 @@ pub fn respond(self: *Request) !void {
     self.httpz_response.body = self.response.content;
 }
 
+/// Set the root value for response data.
+/// ```zig
+/// var root = request.data(.object)
+/// var root = request.data(.array)
+/// ```
+pub fn data(self: Request, comptime root: @TypeOf(.enum_literal)) !*jetzig.Data.Value {
+    return try self.response_data.root(root);
+}
+
 /// Render a response. This function can only be called once per request (repeat calls will
 /// trigger an error).
 pub fn render(self: *Request, status_code: jetzig.http.status_codes.StatusCode) jetzig.views.View {
@@ -330,24 +340,45 @@ pub fn params(self: *Request) !*jetzig.data.Value {
         .JSON => {
             if (self.body.len == 0) return self.queryParams();
 
-            var data = try self.allocator.create(jetzig.data.Data);
-            data.* = jetzig.data.Data.init(self.allocator);
-            data.fromJson(self.body) catch |err| {
+            var params_data = try self.allocator.create(jetzig.data.Data);
+            params_data.* = jetzig.data.Data.init(self.allocator);
+            params_data.fromJson(self.body) catch |err| {
                 switch (err) {
                     error.SyntaxError, error.UnexpectedEndOfInput => return error.JetzigBodyParseError,
                     else => return err,
                 }
             };
-            return data.value.?;
+            return params_data.value.?;
         },
         .HTML, .UNKNOWN => return self.parseQuery(),
     }
 }
 
-// TODO
-// pub fn expectParams(self: Request, T: type) ?T {
-//
-// }
+/// Expect params that match a struct defined by `T`. If any required params are missing (or
+/// cannot be matched to an enum param) then `null` is returned, otherwise a new `T` is returned
+/// with values populated from matched params.
+/// In both cases, `request.paramsInfo()` returns a hashmap keyed by all fields specified by `T`
+/// and with values of `ParamInfo`.
+/// A field in `T` can be an `enum`. In this case, if the param is a string (always true for
+/// query params) then it is coerced to the target enum type if possible.
+pub fn expectParams(self: *Request, T: type) !?T {
+    return try jetzig.http.params.expectParams(self, T);
+}
+
+/// Information about request parameters after a call to `request.expectParams`. Call
+/// `request.paramsInfo()` to initialize.
+///
+/// Use `get` to fetch information about a specific param.
+///
+/// ```zig
+/// const params = try request.expectParams(struct { foo: []const u8 });
+/// const params_info = try request.paramsInfo();
+/// const foo_info = params_info.get("foo");
+/// ```
+pub fn paramsInfo(self: Request) !?jetzig.http.params.ParamsInfo {
+    const params_info = self._params_info orelse return null;
+    return try params_info.init(self.allocator);
+}
 
 /// Retrieve a file from a `multipart/form-data`-encoded request body, if present.
 pub fn file(self: *Request, name: []const u8) !?jetzig.http.File {
@@ -364,13 +395,13 @@ pub fn file(self: *Request, name: []const u8) !?jetzig.http.File {
 pub fn queryParams(self: *Request) !*jetzig.data.Value {
     if (self.query_params) |parsed| return parsed.data.value.?;
 
-    const data = try self.allocator.create(jetzig.data.Data);
-    data.* = jetzig.data.Data.init(self.allocator);
+    const params_data = try self.allocator.create(jetzig.data.Data);
+    params_data.* = jetzig.data.Data.init(self.allocator);
     self.query_params = try self.allocator.create(jetzig.http.Query);
     self.query_params.?.* = jetzig.http.Query.init(
         self.allocator,
         self.path.query orelse "",
-        data,
+        params_data,
     );
     try self.query_params.?.parse();
     return self.query_params.?.data.value.?;
@@ -395,13 +426,13 @@ fn parseQuery(self: *Request) !*jetzig.data.Value {
         return self.parsed_multipart.?.value.?;
     }
 
-    const data = try self.allocator.create(jetzig.data.Data);
-    data.* = jetzig.data.Data.init(self.allocator);
+    const params_data = try self.allocator.create(jetzig.data.Data);
+    params_data.* = jetzig.data.Data.init(self.allocator);
     self.query_body = try self.allocator.create(jetzig.http.Query);
     self.query_body.?.* = jetzig.http.Query.init(
         self.allocator,
         self.body,
-        data,
+        params_data,
     );
 
     try self.query_body.?.parse();
diff --git a/src/jetzig/http/params.zig b/src/jetzig/http/params.zig
new file mode 100644
index 0000000..53c6c16
--- /dev/null
+++ b/src/jetzig/http/params.zig
@@ -0,0 +1,161 @@
+const std = @import("std");
+
+const jetzig = @import("../../jetzig.zig");
+
+/// See `Request.expectParams`.
+pub fn expectParams(request: *jetzig.http.Request, T: type) !?T {
+    const actual_params = try request.params();
+
+    var t: T = undefined;
+
+    const fields = std.meta.fields(T);
+    var statuses: [fields.len]ParamInfo = undefined;
+    var failed = false;
+
+    inline for (fields, 0..) |field, index| {
+        if (actual_params.get(field.name)) |value| {
+            switch (@typeInfo(field.type)) {
+                .optional => |info| if (value.coerce(info.child)) |coerced| {
+                    @field(t, field.name) = coerced;
+                    statuses[index] = .{ .present = value.* };
+                } else |err| {
+                    failed = true;
+                    statuses[index] = .{ .failed = .{ .err = err, .value = value.* } };
+                },
+                // coerce value to target type, null on coerce error (e.g. numeric expected)
+                else => {
+                    if (value.coerce(field.type)) |coerced| {
+                        @field(t, field.name) = coerced;
+                        statuses[index] = .{ .present = value.* };
+                    } else |err| {
+                        failed = true;
+                        statuses[index] = .{ .failed = .{ .err = err, .value = value.* } };
+                    }
+                },
+            }
+        } else if (@typeInfo(field.type) == .optional) {
+            // if no matching param found and params struct provides a default value, use it,
+            // otherwise set value to null
+            @field(t, field.name) = if (field.default_value) |default_value|
+                @as(*field.type, @ptrCast(@alignCast(@constCast(default_value)))).*
+            else
+                null;
+            statuses[index] = .blank;
+            // We don't set `failed = true` here because optional values are not required.
+        } else {
+            statuses[index] = .blank;
+            failed = true;
+        }
+    }
+
+    request._params_info = .{
+        .fields = try std.BoundedArray([]const u8, 1024).init(@intCast(fields.len)),
+        .params = try std.BoundedArray(ParamInfo, 1024).init(@intCast(fields.len)),
+        .required = try std.BoundedArray(bool, 1024).init(@intCast(fields.len)),
+    };
+    inline for (fields, 0..) |field, index| {
+        request._params_info.?.fields.set(index, field.name);
+        request._params_info.?.params.set(index, statuses[index]);
+        request._params_info.?.required.set(index, @typeInfo(field.type) != .optional);
+    }
+
+    if (failed) {
+        return null;
+    }
+
+    return t;
+}
+
+/// See `Request.paramsInfo`.
+pub const ParamsInfo = struct {
+    params: std.BoundedArray(ParamInfo, 1024),
+    fields: std.BoundedArray([]const u8, 1024),
+    required: std.BoundedArray(bool, 1024),
+    state: enum { initial, ready } = .initial,
+    hashmap: std.StringHashMap(ParamInfo) = undefined,
+
+    pub fn init(self: ParamsInfo, allocator: std.mem.Allocator) !ParamsInfo {
+        var hashmap = std.StringHashMap(ParamInfo).init(allocator);
+        try hashmap.ensureTotalCapacity(@intCast(self.params.len));
+        for (self.fields.constSlice(), self.params.constSlice()) |field, param_info| {
+            hashmap.putAssumeCapacity(field, param_info);
+        }
+        return .{
+            .params = self.params,
+            .fields = self.fields,
+            .required = self.required,
+            .hashmap = hashmap,
+            .state = .ready,
+        };
+    }
+
+    /// Get a information about a param. Provides param status (present/blank/failed) and
+    /// original values. See `ParamInfo`.
+    pub fn get(self: ParamsInfo, key: []const u8) ?ParamInfo {
+        std.debug.assert(self.state == .ready);
+        return self.hashmap.get(key);
+    }
+
+    /// Detect if any required params are blank or if any errors occurred when coercing params to
+    /// their target type.
+    pub fn isValid(self: ParamsInfo) bool {
+        for (self.params.constSlice(), self.required.constSlice()) |param, required| {
+            if (required and param == .blank) return false;
+            if (param == .failed) return false;
+        }
+        return true;
+    }
+
+    pub fn format(self: ParamsInfo, _: anytype, _: anytype, writer: anytype) !void {
+        std.debug.assert(self.state == .ready);
+        var it = self.hashmap.iterator();
+        try writer.print("{s}{{ ", .{
+            if (self.isValid())
+                jetzig.colors.green(@typeName(@TypeOf(self)))
+            else
+                jetzig.colors.red(@typeName(@TypeOf(self))),
+        });
+        while (it.next()) |entry| {
+            try writer.print("[" ++ jetzig.colors.blue("{s}") ++ ":{}] ", .{ entry.key_ptr.*, entry.value_ptr.* });
+        }
+        try writer.writeByte('}');
+    }
+};
+
+/// Status of a param as defined by the last call to `expectParams`.
+pub const ParamInfo = union(enum) {
+    /// The field was matched and coerced correctly. `value` is the original param value.
+    present: jetzig.Data.Value,
+    /// The field was not present (regardless of whether the field was optional)
+    blank: void,
+    /// The field was present but could not be coerced to the required type
+    failed: ParamError,
+
+    /// `err` is the error triggered by the type coercion attempt, `value` is the original param
+    /// value.
+    pub const ParamError = struct {
+        err: anyerror,
+        value: jetzig.Data.Value,
+
+        pub fn format(self: ParamError, _: anytype, _: anytype, writer: anytype) !void {
+            try writer.print(
+                jetzig.colors.red("{s}") ++ ":\"" ++ jetzig.colors.yellow("{}") ++ "\"",
+                .{ @errorName(self.err), self.value },
+            );
+        }
+    };
+
+    pub fn format(self: ParamInfo, _: anytype, _: anytype, writer: anytype) !void {
+        switch (self) {
+            .present => |present| try writer.print(
+                jetzig.colors.green("present") ++ ":\"" ++ jetzig.colors.cyan("{}") ++ "\"",
+                .{present},
+            ),
+            .blank => try writer.writeAll(jetzig.colors.yellow("blank")),
+            .failed => |failed| try writer.print(
+                jetzig.colors.red("failed") ++ ":" ++ jetzig.colors.cyan("{}") ++ "",
+                .{failed},
+            ),
+        }
+    }
+};
diff --git a/src/jetzig/testing.zig b/src/jetzig/testing.zig
index e0b6908..b52957a 100644
--- a/src/jetzig/testing.zig
+++ b/src/jetzig/testing.zig
@@ -151,7 +151,7 @@ pub fn expectJson(expected_path: []const u8, expected_value: anytype, response:
 
     const json_banner = "\n{s}";
 
-    if (data.ref(std.mem.trimLeft(u8, expected_path, &.{'.'}))) |value| {
+    if (data.ref(expected_path)) |value| {
         switch (value.*) {
             .string => |string| switch (@typeInfo(@TypeOf(expected_value))) {
                 .pointer, .array => {
diff --git a/src/jetzig/testing/App.zig b/src/jetzig/testing/App.zig
index 9df1e04..9b99e42 100644
--- a/src/jetzig/testing/App.zig
+++ b/src/jetzig/testing/App.zig
@@ -345,7 +345,16 @@ fn buildOptions(allocator: std.mem.Allocator, app: *const App, args: anytype) !R
             if (std.mem.eql(u8, field.name, "body")) continue;
         }
 
-        @compileError("Unrecognized request option: " ++ field.name);
+        @compileError(std.fmt.comptimePrint(
+            "Unrecognized request option `{s}`. Expected: {{ {s}, {s}, {s}, {s} }}",
+            .{
+                jetzig.colors.yellow(field.name),
+                jetzig.colors.cyan("headers"),
+                jetzig.colors.cyan("json"),
+                jetzig.colors.cyan("params"),
+                jetzig.colors.cyan("body"),
+            },
+        ));
     }
 
     return .{
diff --git a/src/jetzig/views/view_types.zig b/src/jetzig/views/view_types.zig
index 5eea082..b23ed69 100644
--- a/src/jetzig/views/view_types.zig
+++ b/src/jetzig/views/view_types.zig
@@ -34,7 +34,7 @@ pub const StaticViewWithArgs = *const fn (
 // `Array.append(.array)`, `Array.append(.object)`, `Object.put(key, .array)`, and
 // `Object.put(key, .object)` also remove the need to use `data.array()` and `data.object()`.
 // The only remaining use is `data.root(.object)` and `data.root(.array)` which we can move to
-// `request.responseData(.object)` and `request.responseData(.array)`.
+// `request.data(.object)` and `request.data(.array)`.
 pub const LegacyViewWithoutId = *const fn (
     *jetzig.http.Request,
     *jetzig.data.Data,