I could not open a boundary file in polyMesh directory

[yiping-song]

Below are the codes which I used to test if I can modify boundary file in the polyMesh directory:

########
from foamlib import FoamFile

below shows that I can open a boundary condition file with no problem

file = FoamFile("rearWing/0/U") # Load a controlDict file
print(file["boundaryField"]["body"]["type"]) # Print the end time
#print(file[None])
file = FoamFile("rearWing/constant/polyMesh/boundary")
print(file["outlet"]["type"])
#########

On running this code, I had following error message:

---

KeyError Traceback (most recent call last)
Cell In[8], line 8
6 #print(file[None])
7 file = FoamFile("rearWing/constant/polyMesh/boundary")
----> 8 print(file["outlet"]["type"])

File ~/envFoam/lib/python3.12/site-packages/foamlib/_files/files.py:918, in FoamFile.getitem(self, keywords)
913 @OverRide
914 def getitem( # ty: ignore[invalid-method-override]
915 self,
916 keywords: str | tuple[str, ...] | None,
917 ) -> "Data | StandaloneData | FoamFile.SubDict | None":
--> 918 return self.getone(keywords)

File ~/envFoam/lib/python3.12/site-packages/multicollections/abc.py:135, in with_default..wrapper(self, key, default)
127 @functools.wraps(meth)
128 def wrapper(
129 self: _Self,
(...) 132 default: _D | _NO_DEFAULT = _NO_DEFAULT, # ty: ignore[invalid-type-form]
133 ) -> _V | _D:
134 try:
--> 135 return meth(self, key)
136 except KeyError:
137 if default is _NO_DEFAULT:

File ~/envFoam/lib/python3.12/site-packages/foamlib/_files/files.py:870, in FoamFile.getone(self, keywords)
867 keywords = FoamFile._normalized_keywords(keywords) # ty: ignore[no-matching-overload]
869 parsed = self._get_parsed()
--> 870 ret = parsed[keywords]
871 if ret is ...:
872 assert keywords

File ~/envFoam/lib/python3.12/site-packages/foamlib/_files/_parsing/init.py:72, in ParsedFile.getitem(self, keywords)
67 @OverRide
68 def getitem( # ty: ignore[invalid-method-override]
69 self, keywords: tuple[str, ...]
70 ) -> Data | StandaloneData | EllipsisType | None:
---> 72 entry = self._parsed[keywords]
73 return entry.data

File ~/envFoam/lib/python3.12/site-packages/multicollections/init.py:70, in MultiDict.getitem(self, key)
65 """Get the first value for a key.
66
67 Raises a KeyError if the key is not found.
68 """
69 if (indices := self._key_indices.get(key)) is None:
---> 70 raise KeyError(key)
71 return self._items[indices[0]][1]

KeyError: ('outlet',)

Below is the boundary file:

/--------------------------------- C++ -----------------------------------
========= |
\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\ / O peration | Website: https://openfoam.org
\ / A nd | Version: 13
\/ M anipulation |
*---------------------------------------------------------------------------*/
FoamFile
{
format ascii;
class polyBoundaryMesh;
location "constant/polyMesh";
object boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

8
(
outlet
{
type patch;
nFaces 32;
startFace 6135;
}
lowerWall
{
type patch;
nFaces 50;
startFace 6167;
}
front
{
type empty;
inGroups List 1(empty);
nFaces 4131;
startFace 6217;
}
inlet
{
type patch;
nFaces 32;
startFace 10348;
}
upperWall
{
type patch;
nFaces 50;
startFace 10380;
}
back
{
type empty;
inGroups List 1(empty);
nFaces 4131;
startFace 10430;
}
body
{
type patch;
nFaces 36;
startFace 14561;
}
rearWing
{
type patch;
nFaces 59;
startFace 14597;
}
)

// ************************************************************************* //

I can see what is the cause of the problem but I do not know how to fix it.

[gerlero]

@yiping-song Sorry for missing this one before. Try it as:

file = FoamFile("rearWing/constant/polyMesh/boundary")
print(file[None][0][1]["type"])

since that file does not strictly contain an OpenFOAM dictionary but a list (accessible as file[None]) of keyword entries (2-tuples of (k, v)).