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49 lines
1.8 KiB
ReStructuredText
49 lines
1.8 KiB
ReStructuredText
.. highlight:: kotlin
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.. raw:: html
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<script type="text/javascript" src="_static/jquery.js"></script>
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<script type="text/javascript" src="_static/codesets.js"></script>
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Updating the contract
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=====================
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Remember that each state references a contract. The contract imposes constraints on transactions involving that state.
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If the transaction does not obey the constraints of all the contracts of all its states, it cannot become a valid
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ledger update.
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We need to modify our contract so that the borrower's signature is required in any IOU creation transaction.
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In ``IOUContract.java``/``IOUContract.kt``, change the imports block to the following:
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.. container:: codeset
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.. literalinclude:: example-code/src/main/kotlin/net/corda/docs/tutorial/twoparty/contract.kt
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:language: kotlin
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:start-after: DOCSTART 01
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:end-before: DOCEND 01
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.. literalinclude:: example-code/src/main/java/net/corda/docs/java/tutorial/twoparty/IOUContract.java
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:language: java
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:start-after: DOCSTART 01
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:end-before: DOCEND 01
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And update the final block of constraints in the ``requireThat`` block as follows:
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.. container:: codeset
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.. literalinclude:: example-code/src/main/kotlin/net/corda/docs/tutorial/twoparty/contract.kt
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:language: kotlin
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:start-after: DOCSTART 02
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:end-before: DOCEND 02
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:dedent: 12
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.. literalinclude:: example-code/src/main/java/net/corda/docs/java/tutorial/twoparty/IOUContract.java
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:language: java
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:start-after: DOCSTART 02
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:end-before: DOCEND 02
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:dedent: 12
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Progress so far
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---------------
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Our contract now imposes an additional constraint - the borrower must also sign an IOU creation transaction. Next, we
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need to update ``IOUFlow`` so that it actually gathers the borrower's signature as part of the flow. |