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Dear all, Working hard in the Collect Survey Designer ( found a video to design Collect Earth surveys in youtube ) and I am trying to design a couple of new surveys. I have managed to get a few XPath validation expressions working but I must admit I am a bit lost... could anyone point me in the right direction of what should I learn, or what are kind of general XPath functions one can use??? Validations, default values and the possibility to show/hide attributes in the interface depending on other values is a strong feature, but documentation is weak... Thanks!! |
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Hi...I have written a document with some XPath examples, based on two inheritance hierarchies among the entities: one more complex (cluster->plot) and one simpler (only plot). See below: Link to document : HERE EXAMPLES OF CODE IN OPEN FORIS Collect General hierarchical structures (either cluster or plot-based) Comparison checks (i.e., start_date, start_time, end_time, tree_no, azimuth, tree distance,dbh, total_height and bole_height): Example attribute (number type): Path: /plot/details/elevation Severity Error Message Elevation must be between 0 and 4000 m 0 <= elevation <= 4000 Example attribute (date type): Path: /cluster/start_date Severity Error Message You have written the starting date in the future! start_date <= idm:currentDate() Example attribute (time type): Path: /cluster/start_time Severity Warning Message Working hours for the survey should be from 06:00 to 19:00! 0600 < start_time <= 1900 Example attribute (time type): Path: /cluster/end_time Severity Error Message End time should be always after start time start_time <= end_time (Here we assume that start_time and end_time are under the same entity, i.e., cluster, or plot) Example attribute (number type): Path: /cluster/plot/tree/tree_no Severity Error Message tree number must be >0 0 < tree_no Example attribute (number type): Path: /cluster/plot/tree/azimuth Severity Error Message angle must be between 0 (inclusive) and 360 (exclusive) 0 <= azimuth < 360 Example attribute (number type, refers to tree distance): Path: /cluster/plot/tree/distance Severity Error Message tree distance must be positive 0 <= distance Severity Error Message tree outside of plot. Plot radius is 12 m. distance <= 12 Example attribute (number type): Path: /cluster/plot/tree/dbh Severity Warning Message Unusually large dbh dbh < 200 Severity Error Message dbh must be positive 0 <= dbh Severity Error Message tree must be at least 20 cm if distance>2 m 20 <= dbh Apply when distance>2 Severity Error Message tree must be at least 5 cm in any case 5 <= dbh Example attribute (number type): Path: /cluster/plot/tree/total_height Severity Warning Message Unusually tall tree total_height < 80 Severity Error Message Impossibly tall tree total_height < 150 Severity Error Message height must be positive 0 <= total_height Example attribute (number type): Path: /cluster/plot/tree/bole_height Severity Error Message bole height must be positive 0 <= bole_height Severity Error Message bole height must be less or equal than total height bole_height <= total_height Default values (i.e., start_date, start_time and tree_no): Example attribute (date type): Path: /cluster/start_date Calculated value expressions: Expression: idm:currentDate() Example attribute (time type): Path: /cluster/start_time Calculated value expressions: Expression: idm:currentTime() Example attribute (number type): Path: /plot/tree/tree_id Calculated value expressions: (it will automatically increase the number every time a new tree is recorded in the plot) Surveys with Plot as sampling unit or root entity and tree as sub-entity Distance checks (i.e., plot position): Example attribute: Path: /plot/details/position Severity Error Message You are more than 50 m from plot location Destination point idm:samplingPointCoordinate(parent()/plot_id) Max distance (m) 50 Severity Warning Message You are more than 20 m from plot location Destination point idm:samplingPointCoordinate( parent()/plot_id) Max distance (m) 20 Autocompletion (click Calculated in the General tab fot the variable) in optional variables from sample design file (i.e., province as a column after design point coordinates in the sampling_design imported file): Example attribute (text type): Path: /plot/details/province Calculated value expressions: Requirednes of variable if expression is satisfied (i.e., tree_height only required every three third tree): Example attribute (text type): Path: /plot/tree/tree_height Required only when expression is verified: tree_id mod 3 = 0 Surveys with Cluster as sampling unit or root entity and plot and tree as sub-entities Distance checks (i.e., plot position): Example attribute: Path: /cluster/plot/details/position Severity Error Message You are more than 100 m from plot location Destination point idm:samplingPointCoordinate(parent()/parent()/cluster_no, parent()/plot_no) Max distance (m) 100 Severity Warning Message You are more than 20 m from plot location Destination point idm:samplingPointCoordinate(parent()/parent()/cluster_no, parent()/plot_no) Max distance (m) 20 Autocompletion(click Calculated in the General tab fot the variable) in optional variables from sample design file (i.e., province as a column after design point coordinates in the sampling_design imported file): Example attribute (text type): Path: /cluster/location/province Calculated value expressions: Example attribute (text type): Path: /cluster/plot/details/province Calculated value expressions: Example attribute (number type): Path: /cluster/plot/tree_count Calculated value expressions: Expression: math:max(parent()/plot/tree/tree_no) Relevance of variable if expression is satisfied (i.e., tree_count, plot position, and tree entity): Example attribute (number type): Path: /cluster/plot/tree_count Relevant only when expression is verified: parent()/plot/details/accessibility=0 Example attribute (coordinates type): Path: /cluster/plot/details/position Relevant only when expression is verified: accessibility=0 (here we don’t need a hierarchical path since position and accessibility belong to the same hierarchy, i.e: parent()/plot/details/position and parent()/plot/details/accessibility) Example entity (multiple table layout): Path: /cluster/plot/tree Relevant only when expression is verified: details/accessibility=0 |
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This is a common question, as the XPath is a language that can be a bit complex for non-programmers, but don't panic, it is really not that hard (and actually quite logical) You can start by looking into the Collect documentation here : |
