LINQ IFC Query Engine CLIF

CLIF in a Nutshell

CLIF is a query engine to read and manipulate IFC files on your local machine. CLIF is based on LINQ and the xBIM.Essentials library. With a LINQ query you can filter entities regarding attributes, types, or other parameters. Furthermore, there are LINQ like queries to add, delete, or update entities.

CLIF is fully based on .Net Core 3.1. Hence, you can compile the code for Windows, Unix or Mac.

Using CLIF

Depending on your requirements, you can either include the CLIF query engine into your project and query your IFC files by creating a new QueryManager and call the PerformQuery method. The QueryResult contains returns information about the success , errors, and, in case of a select query, the returned object.

string ifcPath = @"TestData\B_Damage_Types.ifc";
CLIF.QueryEngine.QueryManager qManager = new QueryManager(ifcFile);
string ifcQuery = "from ifcEntity in model.Instances where ifcEntity.ExpressType.Name == \"IfcBeam\" select ifcEntity"
CLIF.QueryEngine.QueryResult result = qManager.PerformQuery(ifcQuery);

In case of changes in the IFC model, remember to save the new model.

qManager.SaveModel("C:\\my\\path\\newmodel.ifc")

A second possibility is to use the console application CLIF.QueryEnvironment which loads an IFC file and processes a command or text file with multiple commands. The example below shows the command line to execute a single query.

QueryEnvironment.exe -i="TestData\B_Damage_Types.ifc" -q="from ifcEntity in model.Instances where ifcEntity.ExpressType.Name == ""IfcBeam"" select ifcEntity" -s="C:\my\path\newmodel.ifc"

Furthermore, the command line application offers an interactive user interface to execute queries.

Using basic LINQ for the IFC files

Please refer to the Introduction to LINQ queries for basic information about Language Integrated Query (LINQ). All IFC entities are stored in model.Instances. Whereby, model is an instance of Xbim.Common.IModel (https://github.com/xBimTeam/XbimEssentials/blob/master/Xbim.Common/IModel.cs). Hence, to access the entities, after the in statement in the query, model.Instances has to follow.

from ifcEntity in model.Instances select ifcEntity

This query language is case sensitive, which means that model.instances with a lower case i leads to an error. However, you are free to choose an entity name. Instead of ifcEntity, you can use everything else.

from myEntity in model.Instances select myEntity

Please omit to use statements or keywords from C# as name for the entity, for instance, class, enum, string, et cetera. Extension methods from LINQ are not usable.

In case you need the returned types as another type, you can cast them within the select section

from ifcEntity in model.Instances where ifcEntity.ExpressType.Name == "IfcBeam" select (Xbim.Ifc4.SharedBldgElements.IfcBeam) ifcEntity

or

from ifcEntity in model.Instances where ifcEntity.ExpressType.Name == "IfcBeam" select ifcEntity as Xbim.Ifc4.SharedBldgElements.IfcBeam

This is helpful for encapsulated queries. Think of the case you want to select all entities with a specified type object.

from ifcProduct in 
(from pr in model.Instances where (pr is Xbim.Ifc4.Interfaces.IIfcProduct select pr as Xbim.Ifc4.Interfaces.IIfcProduct)
where (ifcProduct.IsTypedBy.Any(x => x.RelatingType.Name.ToString().StartsWith("Damage type:"))) select ifcProduct as Xbim.Ifc4.Interfaces.IIfcProduct 

If you dive deeper into xBIM, you can also do the same with the Method OfType from the IModel interface.

from ifcProduct in (model.Instances.OfType<Xbim.Ifc4.Interfaces.IIfcProduct>()) where (ifcProduct.IsTypedBy.Any(x => x.RelatingType.Name.ToString().StartsWith("Damage type:"))) select ifcProduct as Xbim.Ifc4.Interfaces.IIfcProduct 

LINQ extensions for update, insert and delete

You find a short summary of the CLIF query structure in the remarks of the class CLIF.QueryEngine.QueryParser. Check out the class CLIF.Tests.LinqQueryCollection for a collection of query examples. Please consider to replace \" with ".

Update

The general structure for the update query is as follows.

update [full xBIM type name of the entity to update] [name of the variable] in model.Instances where [condition] { [C# code] }

[full xBIM type name of the entity to update]

The query needs the exact type of the entities to update. This might be an interface from Xbim.Essentials or a full specified type.

[name of the variable]

This is the name of the variable or entity, which is used within the where part of the query and within the later code for updating.

[condition]

The condition for filtering the elements for updating. Please refer to Basic LINQ Query Operations (C#) for further information about filtering.

[C# code]

This source code is meant to update your entity. Please use the [variable name]to access a single entity after filtering. Every line of code has to end with a semicolon.

Example

The following code snippet shows a query, to set the name of all IfcBeam entities to Hello World.

update Xbim.Ifc4.SharedBldgElements.IfcBeam beam in model.Instances where beam.ExpressType.Name == "IfcBeam" {beam.Name = "Hello World";};

Insert

The insert command is comparable to the update command. The general structure is as follows.

insert [full xBIM type name of the entity to insert] [name of the variable] in model.Instances { [C# code] }

[full xBIM type name of the entity to update]

The query needs the exact type of the entities to update. This might be an interface from Xbim.Essentials or a full specified type.

[name of the variable]

This is the name of the variable or entity, which is used within the where part of the query and within the later code for updating.

[C# code]

This source code is meant to initialize your entity. Please use the [variable name]to access the new created entity. Every line of code has to end with a semicolon.

Example

The example below illustrates a query to add a new proxy with the name "My new Proxy".

insert Xbim.Ifc4.Kernel.IfcProxy proxy in model.Instances {proxy.Name = "My new Proxy";}

Delete

The delete command looks as follows.

delete [name of the variable] in model.Instances where [condition]

[name of the variable]

This is the name of the variable or entity, which is used within the where part of the query and within the later code for updating.

[condition]

The condition for filtering the elements for updating. Please refer to Basic LINQ Query Operations (C#) for further information about filtering.

Example

The example below deletes the entity with the IFC number 9010.

delete ifcEntity in model.Instances where ifcEntity.EntityLabel == 9010

Further documentation

CLIF Query Environment

Developer Documentation