FIX: Replace TotalReadoutTime check to allow alternatives

Author: effigies

src/schema/rules/checks/fmap.yaml

@@ -65,3 +65,19 @@ EPISmallBVals:
     - '"bval" in associations'
   checks:
     - min(associations.bval.values) < 100
+
+TotalReadoutTimeMustDefine:
+  issue:
+    code: TOTAL_READOUT_TIME_MUST_DEFINE
+    message: |
+      You must provide enough metadata to determine the TotalReadoutTime of this file.
+      `TotalReadoutTime` or `EffectiveEchoSpacing` satisfy this criterion.
+    level: error
+  selectors:
+    - datatype == "fmap"
+    - suffix == "epi"
+    - match(extension, "^\.nii(\.gz)?$")
+  checks:
+    - |
+      sidecar.TotalReadoutTime ||
+      sidecar.EffectiveEchoSpacing

src/schema/rules/sidecars/fmap.yaml

@@ -60,15 +60,27 @@ MRIFieldmapDirectFieldMapping:
         Fieldmaps must be in units of Hertz (`"Hz"`),
         radians per second (`"rad/s"`), or Tesla (`"T"`).
 
-# Case 4: Multiple phase encoded directions ("pepolar")
+# Case 4: Multiple phase-encoded directions ("pepolar")
 MRIFieldmapPepolar:
   selectors:
     - datatype == "fmap"
     - suffix == "epi"
     - match(extension, '\.nii(\.gz)?$')
   fields:
-    PhaseEncodingDirection: required
-    TotalReadoutTime: required
+    PhaseEncodingDirection:
+      level: required
+      issue:
+        code: PHASE_ENCODING_DIRECTION_MUST_DEFINE
+        message: |
+          You have to define 'PhaseEncodingDirection' for this file.
+    TotalReadoutTime:
+      level: optional
+      level_addendum: |
+        required if other methods for calculating readout time are not present
+    EffectiveEchoSpacing:
+      level: optional
+      level_addendum: |
+        required if other methods for calculating readout time are not present
 
 TB1EPI:
   selectors:

src/schema/rules/sidecars/mri.yaml

@@ -241,19 +241,6 @@ PhaseEncodingDirectionRec:
         (see [Case 4: Multiple phase encoded
         directions](#case-4-multiple-phase-encoded-directions-pepolar))
 
-PhaseEncodingDirectionReq:
-  selectors:
-    - datatype == "fmap"
-    - suffix == "epi"
-    - match(extension, "^\.nii(\.gz)?$")
-  fields:
-    PhaseEncodingDirection:
-      level: required
-      issue:
-        code: PHASE_ENCODING_DIRECTION_MUST_DEFINE
-        message: |
-          You have to define 'PhaseEncodingDirection' for this file.
-
 MRITimingParameters:
   selectors:
     - modality == "mri"