DHTMLX Planning Engine Documentation

Common types#

Scalar formats, enum values and small object shapes that several payloads share. Field names are given in wire spelling. Id, DateValue, TimeUnit, ConstraintType, Pause, ResourceData, Subtree, AnalyticsOptions and ProfileQuery are named types in the package's TypeScript declarations. The other sections describe value sets that the declarations write inline on the fields that use them.

Id#

An id of a task, link, calendar, resource, assignment, slot or candidate.

type Id = string | number;

Ids are compared like JavaScript object keys, so 1 and "1" are the same id. Numeric ids are double-precision floats; send ids beyond Number.MAX_SAFE_INTEGER as strings. Whole-number ids come back as JSON integers.

[1, "1", "task-7", 2.5]

The first two values name the same object.

Used wherever a payload references an object: id, parent, source, target, task, resource, calendar_id and the id lists in results. See Wire format.

DateValue#

A naive local date-time at minute precision, sent as a string. It has no timezone and no daylight saving.

type DateValue = string | Date;
Direction Form
Input YYYY-MM-DD, YYYY-MM-DD HH:mm or YYYY-MM-DDTHH:mm, each with optional :ss. A bare date means 00:00. Seconds are dropped.
Output Always YYYY-MM-DD HH:mm. 
["2026-03-02", "2026-03-02 08:00", "2026-03-02T08:00:30"]

These inputs come back as "2026-03-02 00:00", "2026-03-02 08:00" and "2026-03-02 08:00". Any other string fails the call with validation, message invalid date, and no path.

Date is accepted only by the JS glue; the raw exports take strings.

Used by task and constraint dates, config.project_start / project_end, profile and leveling ranges, and every date in a result.

TimeUnit#

The unit of a duration or lag.

type TimeUnit = "minute" | "hour" | "day";

"week", "month" and "year" are reserved and fail with validation. In the elapsed fields leveling_delay and pauses, an hour is 60 minutes and a day is 24 hours.

Used by SchedulingConfig.duration_unit (default "day"), TaskData.duration_unit and LinkData.lag_unit.

ConstraintType#

A task's scheduling constraint. Matching is case-insensitive.

Value Constraint Needs constraint_date
"asap" As soon as possible no
"alap" As late as possible no
"snet" Start no earlier than yes
"snlt" Start no later than yes
"fnet" Finish no earlier than yes
"fnlt" Finish no later than yes
"mso" Must start on yes
"mfo" Must finish on yes

Used by TaskData.constraint_type, TaskUpdate.constraint_type and the constraint-violation conflict. How constraints act is in Links, constraints and summaries.

Gap behavior#

How tasks are placed when links leave room.

Value Effect
"preserve" Default. Tasks keep their preferred dates when links allow.
"compress" Every task moves to its earliest position.

Used by SchedulingConfig.gap_behavior.

Calendar mode#

Which calendars the work of a task runs on.

Value Effect
"resource" Default. Each assignment works on its resource's calendar combined with the task's.
"task" Task calendars only.
"task-inherited" Task calendars only; a task without calendar_id uses its nearest ancestor's.

Used by SchedulingConfig.calendar_mode. The rules are in Working-time calendars.

Load basis#

The bucket size for resource load.

Value Bucket
"hour" One hour
"day" One day

When a basis field is omitted, it's derived from config.duration_unit: "day" for day, "hour" for hour and minute. Used by LevelingOptions.basis, ProfileQuery.basis and LoadProfile.basis.

The dependency type of a link.

Value Accepted forms Dependency
FS "fs", 0, "0" Finish to start (default)
SS "ss", 1, "1" Start to start
FF "ff", 2, "2" Finish to finish
SF "sf", 3, "3" Start to finish

Strings match in any case, so "FS" is accepted. Other numbers and strings fail with validation. Used by LinkData.type and the link entries of SchedulingChanges.

Task type#

The kind of a task.

Value Kind
"task" A leaf task (default)
"summary" A summary task whose span covers its children
"project" Input alias of "summary"; output says "summary"
"milestone" A zero-duration point

Used by TaskData.type. Result entries report the kind as kind on Mutation.

Validation mode#

How a project treats invalid input.

Value Effect
"strict" Default. Invalid input fails the call with validation.
"repair" Coerces invalid data (duplicate ids, missing or inconsistent dates, dated constraints without a date) and reports each fix as a repaired note.

Used by ProjectOptions.validation in the JsonProject constructor. See Accept messy input.

Pause#

One leveling split of a task.

Field Type Required Default Description
at number yes - Start of the pause after the task start. Elapsed time in the task's duration_unit, finite and >= 0
length number yes - Length of the pause. Elapsed time in the task's duration_unit, finite and > 0
by "leveling" | null no absent Who wrote the pause. "leveling" is the only value; the leveler sets it on every pause it writes

A pause occupies the whole minutes from round(at) to round(at + length). A pause that rounds to zero length is ignored. Unknown fields are ignored.

Used by TaskData.pauses, TaskUpdate.pauses and Mutation.pauses. How pauses affect dates and load is in Leveling resources.

ResourceData#

A resource that assignments book.

Field Type Required Default Description
id Id yes - Resource id
capacity number | null no config.default_resource_capacity (1) Units the resource can carry per bucket, in assignment value units (1 = 100 %). Finite and >= 0
calendar_id Id | null no none The resource's calendar. With calendar_mode: "resource" it must name a calendar in ProjectData.calendars

Unknown fields are ignored. An invalid capacity fails with validation at resources[i].capacity; an unknown calendar_id at resources[i].calendar_id.

Used by ProjectData.resources and resources.add in SchedulingChanges. An edit to an existing resource is a ResourceUpdate.

Subtree#

Limits a run to one branch of the task tree.

Field Type Required Default Description
task Id yes - Root task of the branch. Must be a known, scheduled task
inclusive boolean | null no true true includes the root task itself; false covers only its descendants

Unknown fields fail with parse. An unknown or unscheduled task fails with validation at subtree.task.

Used by SolveOptions.subtree and PreviewOptions.subtree. See Reschedule a branch.

AnalyticsOptions#

Requests analytics in a result.

Field Type Required Default Description
criticalPath boolean | null no false Adds analytics.criticalPath
slack boolean | null no false Adds analytics.slack

Unknown fields fail with parse. The filled shape is Analytics.

Used by SolveOptions.analytics, PreviewOptions.analytics and AnalyzeOptions.analytics.

ProfileQuery#

The range and resources a load profile covers.

Field Type Required Default Description
from DateValue yes - Range start. Buckets whose start lies in [from, to) are reported
to DateValue yes - Range end, after from
resources Id[] | null no every resource Resources to report, in this order
basis "hour" | "day" | null no derived from config.duration_unit Bucket size
tasks "none" | "overallocated" | "all" | null no "none" Task ids per bucket: none (the field is absent), only in buckets where load exceeds capacity, or every booked task

Unknown fields fail with parse. to not after from, or more than 100 000 buckets per resource, fails with validation at to; an unknown resource id at resources.

Used by PreviewOptions.profile. LoadProfileOptions takes the same fields flat, plus baselineId. The result is a LoadProfile.