Using memory layer as input with processing runalg in PyQGIS

Question

My first processing runalg creates a memory layer as output. I need to use this layer as the input for the second runalg.

#first
processing.run("qgis:fieldcalculator", {'INPUT':'test_1_f08f5cd1_13ea_445b_9778_6ee0ab919030','FIELD_NAME':'1.3-field','FIELD_TYPE':0,'FIELD_LENGTH':10,'FIELD_PRECISION':3,'NEW_FIELD':True,'FORMULA':'((length(shortest_line(centroid($geometry),boundary($geometry)))))*1.3','OUTPUT':'memory:'})

#second
processing.run("qgis:fieldcalculator", {'INPUT':?????,'FIELD_NAME':'1.3-field','FIELD_TYPE':0,'FIELD_LENGTH':10,'FIELD_PRECISION':3,'NEW_FIELD':True,'FORMULA':'((length(shortest_line(centroid($geometry),boundary($geometry)))))*1.3','OUTPUT':'memory:'})

I have found this links but none could help me.

• Using memory layer as input and/or output with runalg?
• Using processing using other output (result from another algorithm) as input

Answer 1

I have chained processing algorithms within a processing script by adding the output of the first algorithm to a sink (see underdark's tutorial) then using dest_id1 (for example) as the input for the next processing script. I found that it was necessary to add the line del sink between uses of the sink and to declare OUTPUT1 = "OUTPUT_1" and OUTPUT2 = "OUTPUT_2" at the start of the script and the syntax at the end that worked for me was:

results = {}
results[self.OUTPUT1] = dest_id1
results[self.OUTPUT2] = dest_id2
return results

All other syntax to do with outputs has to be duplicated. Good luck:)